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Marine Mammals of Rhode Island, Part 8, Harp Seal

by Robert D. Kenney

Harp seal at Napatree Point, Westerly, March 16, 2015. Photo: C.S. Spencer

Harp seal at Napatree Point, Westerly, March 16, 2015. Photo: C.S. Spencer

Now where were we? Installment 6 in this series on the marine mammals of Rhode Island was on harbor seals. The next was supposed to be about harp seals to contrast the two species, but the unusual appearance of a beluga in the Bay last summer upset the plan. Since no other oddball marine mammals have been sighted recently, we can go back to the planned sequence.

Unlike our resident harbor seals, harp seals are merely visitors to New England or mid-Atlantic waters. They come down from their home waters much farther to the north. Their scientific name, Pagophilus groenlandicus, translates as “ice-lover from Greenland.” They are one of two species of so-called ice seals that visit our area frequently, but it has not always been so.

Harp seals are found only in the North Atlantic and Arctic, from eastern Canada east to northwestern Russia. There are three breeding populations, in the White Sea north of Russia, in the Greenland Sea near Jan Mayen, and in two locations near Newfoundland—the “Front herd” to the northeast and the “Gulf herd” to the west. Their distributions during the remainder of their annual cycle, when they are at sea and foraging, are poorly known.

Harp seals have traditionally been hunted for subsistence use by the Inuit in Greenland and eastern Canada. They still are hunted in Greenland; one of the first returns of a flipper tag from a live-stranded harp seal that had been rehabilitated and released by Mystic Aquarium came from an Inuit hunter in Greenland. Early European settlers in North America did not immediately exploit harp seals, since other species (walrus, gray seal, and harbor seal) were more accessible. Winter harp seal hunting began in the St. Lawrence River in the mid-17th century. Hunters at first shot seals on the ice from boats, but quickly adopted the Inuit methods of capturing them with nets. Within 100 years harp sealing had spread throughout the Gulf and along the northeastern coast of Newfoundland, with the take in some years well over 100,000 seals.

Harp seal at Napatree Point, Westerly, March 16, 2015. Photo: C.S. Spencer.

Harp seal at Napatree Point, Westerly, March 16, 2015. Photo: C.S. Spencer.

It was also in the 18th century that the early spring hunt for white-coat pups began, taking advantage of pupping areas on the pack ice that were easily accessible from shore. In the 19th century, steam-powered ships enabled additional expansion of the hunt, with annual takes ranging from 500,000 to 740,000 seals. Oil rendered from the blubber layer was the main product of the seal hunt, until tanning methods (developed in the 1940s and 1950s) made the pelts of white-coat harp seal pups extremely valuable. Because of widespread opposition to the white-coat hunt by environmental organizations and a European ban on importation of white-coat pelts, commercial hunting of seal pups was banned in Canada in 1987. Hunting is now restricted to non-breeding adults, juveniles, and independent, post-weaning pups.

The harp seal hunts in Canada and Greenland are currently managed under quotas set by federal agencies. Total annual take in the two countries, by commercial and subsistence hunters, is between 200,000 and 400,000 harp seals. There is also significant mortality caused by entanglement in Canadian gillnet fisheries, averaging about 12,000 a year. Entanglement mortality in U.S. fisheries is much lower, averaging 200–300 per year.

Harp seals are not listed under the U.S. Endangered Species Act or Canada’s Species at Risk Act, and are classified as Least Concern on the IUCN Red List. Despite the substantial annual harvests by hunters, the abundance of harp seals in the eastern Canadian populations appears to have increased steadily, from 3.1 million in 1990 to 7.1 million in 2012. We have absolutely no idea how many harp seals might occur in northeastern U.S. waters.

Description: Adult harp seals are relatively distinctive and easily recognized. While they are roughly the same size (1.7–1.9 m) and shape as harbor seals, with heads that appear slightly smaller, their color pattern is distinctive. An adult has a pale white to silvery-gray body with a black face and a black inverted V- or harp-shaped marking on the back.

To get to that adult pattern, harp seals go through a well-defined sequence of coats or pelages. Pups known as “thin white-coats” are born covered in a fine, white fetal fur or lanugo. They become “fat white-coats” as they gain weight during nursing. At weaning, the juvenile coat has filled in and is visible under the white lanugo. The pup is now known as a “gray-coat.” The lanugo is shed after weaning, and the pup then has a silvery juvenile coat with scattered dark blotches. At this stage young seals are referred to as “beaters” because of their awkward, splashing manner of swimming on the surface. The second molt occurs at 13 to 14 months into a similar “bedlamer” pelage, with somewhat more dark patches. Juveniles are easy to tell from similar-sized harbor seals because they are much less spotted. Juvenile and adult harp seals molt annually in April and May, hauling out in dense aggregations on the pack ice north of the breeding areas. The adult pattern is attained at the time of sexual maturity, but some females never completely develop the harp pattern. Adults with the intermediate pattern of both a partially developed harp marking and typical juvenile dark blotches are known as “spotted harps.”

Natural history: Harp seals are gregarious in their northern range, hauling out for pupping and molting in large aggregations. In or near Rhode Island, however, they are most often solitary juveniles. Only three adults (one stranded dead, one photographed alive but extremely emaciated, and one apparently healthy) have been reported in Rhode Island. Unlike the harbor seal’s preference for rocky ledges, harbor seals are most often seen on relatively flat, sandy beaches, which are often speculated to resemble sea ice. Harp seals in their usual range are associated with sea ice, with an annual migration following the annual cycle of pack ice, moving north in summer and south in winter.

Female harp seals give birth to single pups on the dense pack ice, where they select areas of thick, hummocky ice that provides protection for pups. These locations are some distance from the ice margin but where open water is still accessible. Females gather in aggregations separated only by a couple of meters from one another. Most pups in the Gulf of St. Lawrence are born between 20 February and 10 March, while births are slightly later off eastern Newfoundland.

Monthly stranding frequencies of harp seals in the Rhode Island study area (from the R.I. Ocean SAMP report).

Monthly stranding frequencies of harp seals in the Rhode Island study area (from the R.I. Ocean SAMP report).

Pups average a meter in length, weigh 11–12 kg at birth, and have little blubber. They nurse for 10–12 days on milk that is up to 43% fat and 10% protein, gaining 2.2 kg per day. Females fast entirely, or feed little, during lactation. They abandon the pups immediately after weaning. At weaning the pups have a 5-cm thick layer of blubber and weigh about 36 kg. Pups then remain on the ice for a post-weaning fasting period as long as 6 weeks, during which they can lose up to half of their body mass.

Mating occurs just after the pup is weaned. It usually takes place in the water, though there have been observations of mating on the ice. Implantation of the embryo is delayed about three months. Adult females breed annually, and both males and females can remain reproductively active into their 20s. Both males and females reach sexual maturity at an average age of 5.5 years, but males generally are not reproductively active and successful until age 8.

Adult harp seals feed on a wide variety of small pelagic and demersal fishes, squid, and crustaceans, especially on capelin and Arctic cod. Pups undergo a transition in prey type and feeding depth during their first year. After the post-weaning fast, pups first feed mainly on “krill” in near-surface waters. At about one year of age, they make a transition to diving to intermediate depths and feeding on pelagic fishes. Some animals simply do not seem to make that transition successfully. The most common harp seal encountered in Rhode Island or the other New England and mid-Atlantic states is a stranded, starved or starving, one-year-old in winter or early spring. Nearly all strandings in our region have been in January–May, with a clear peak in February (22%), March (42%), and April (22%).

A juvenile harp seal on the beach at the URI Bay Campus in February 2008, just before it was collected by Mystic Aquarium staff and taken in for rehabilitation (photo by the author).

A juvenile harp seal on the beach at the URI Bay Campus in February 2008, just before it was collected by Mystic Aquarium staff and taken in for rehabilitation (photo by the author).

Stranded harp seals are often found with their stomachs filled with stones and shells, leading to serious medical complications or death. It has been speculated that this arises as a consequence of their habit of eating ice as a source of fresh water. Stranding response protocols for ice seals have been modified in an attempt to recover starving juveniles as soon as possible before they have a chance to start eating stones.

Historical occurrence: Until recently harp seals were very rare in the Rhode Island study area and nearly as rare from Massachusetts to Maine. Cronan and Brooks knew of no records from Rhode Island. There were poorly documented occurrences in the 19th Century in Connecticut and New Jersey. The only well-documented historical record south of Massachusetts was an adult male captured at Cape Henry, Virginia, in March 1945—recorded in a newspaper photograph.

Harp seals in the Rhode Island study area are known almost exclusively from strandings, both live and dead. Strandings have been widespread on ocean-facing beaches throughout Long Island, Connecticut, and Rhode Island. Strandings are common on both sides of Long Island Sound, more than any other species of seal. Harp seals also make occasional appearances well inland up rivers, especially when the river has frozen over. I saw one on the ice on the Narrow River not far from my house in February 2004.

Annual stranding frequencies of harp seals in Rhode Island, 1989-2005 (from the R.I. Ocean SAMP report).

Annual stranding frequencies of harp seals in Rhode Island, 1989-2005 (from the R.I. Ocean SAMP report).

Recent occurrence: The first harp seal stranding in Rhode Island was near the Quonochontaug Breachway in Charlestown in May 1989. One stranded on Napatree Point in Westerly in April 1990, another at Mackerel Cove in Jamestown in January 1992, and another at Misquamicut Beach in Westerly in January 1993. Stranding numbers began to increase in 1994, with seven that year, and showed a dramatic peak in 2001. This pattern is similar to what is seen on a wider, regional basis. Beginning in the late 1980s, harp seal occurrences began to increase in the Gulf of Maine, with the increase somewhat later in the mid-Atlantic. Since 1995, harp seal strandings in the mid-Atlantic have exceeded those of harbor seals in most years.

The increase in juvenile harp seal occurrences in our region in the 1990s coincided with growth of the seal population in Canada and with declines in many fish stocks. Some have speculated that juveniles are forced to disperse more widely because of competition for prey, however, there are complicating factors such as changes in climatic and oceanographic conditions.

Coming next in Marine Mammals of Rhode Island: Fin Whale

Posted in Animals, Biodiversity, Climate, Education, Historical, News |

Marine Mammals of Rhode Island, Part 7, Beluga

by Robert D. Kenney

Installment 7 in this series on the marine mammals of Rhode Island was supposed to be on harp seals, but recent events have forced us to let the beluga cut in line without waiting its turn. In June, on the afternoon of Father’s Day, two different belugas were sighted in our local waters. Dale Denelle, a local real-estate broker and fisherman, was fishing for stripers in the West Passage between Whale Rock and Beavertail, when he saw something unusual coming toward his boat. He managed to shoot some cell-phone video, which he posted on line (HERE on Vimeo). Better yet, he correctly identified the animal as a beluga, recognized that it was not the usual thing one might see off the Narragansett shore, and sent word of his sighting to the Graduate School of Oceanography. What Dale had spotted was the first-ever documented occurrence of a beluga in Rhode Island. We found out later that another fisherman had seen a beluga in the Assonet River near Fall River on the same afternoon. Although it was in Massachusetts, it had to swim through Rhode Island waters to get there or to leave.

beluga v narwhalBelugas are also known as white whales; the word “beluga” or “belukha” comes from the Russian word for “white.” Belugas and narwhals together comprise the family Monodontidae; which is closely related to the dolphin and porpoise families. Belugas and narwhals are both found almost exclusively in the Arctic. (LINK to the really terrific narwhal book just published by nature writer and RINHS board member Todd McLeish) They are the last survivors of a family that was formerly more widespread in Northern Hemisphere temperate latitudes. Belugas occur all around the Arctic Ocean—in Alaska, Canada, Greenland, Svalbard, Norway, and Russia—in 29 separate, identified regional populations or stocks. Stock differentiation is likely maintained by strong “matrilineal habitat fidelity”—animals return to the same summering habitats that they first visited with their mothers. Two of the stocks—in Cook Inlet in southern Alaska and in the St. Lawrence River and Estuary in southeastern Canada—are referred to as “relict” populations. They were apparently stranded in those estuarine systems as the glaciers retreated at the end of the last Ice Age, and now are totally isolated from all of the Arctic beluga stocks.

The total abundance of beluga whales worldwide is estimated to be at least 150,000. Belugas are not listed under the U.S. Endangered Species Act or on the Rhode Island state list, and are classified as Near Threatened on the IUCN Red List. The St. Lawrence Estuary stock has been estimated at 1,000–1,200 whales and is listed as Threatened under the Species At Risk Act in Canada.

Belugas are taken by subsistence hunters in many parts of the species’ range, including northwest Alaska. In the St. Lawrence estuary, they were hunted for over 400 years until the hunt was prohibited in 1979. The peak years of the St. Lawrence beluga hunt were 1880–1950. The St. Lawrence beluga population may have been as large as about 5,000–10,000 at the beginning of the 20th Century, declining to only about 350 individuals in the 1970s.

A serious concern with St. Lawrence estuary beluga whales is the issue of toxic contamination and associated health effects. The St. Lawrence River is the outlet from the Great Lakes and a substantial watershed in the industrial center of North America. There are contaminants in the water and sediments, accumulating up the food chain to the belugas at the top. St. Lawrence belugas have much higher loads of many contaminants than Arctic belugas. The effects of these contaminants include direct toxicity, suppression of the immune system, effects on the reproductive system, mutation, and cancer. Over a third of all known tumors recorded from cetaceans have been in St. Lawrence River belugas.

beluga swimmingDescription: Beluga whales may be the easiest cetaceans to identify (or it’s a tie with killer whales). Adult females are up to 4 m long. The maximum recorded size for a male was 6 m, but they usually do not reach more than about 4.5 m. Belugas have stocky bodies with no dorsal fin, instead there is a low dorsal ridge about 50 cm long but only 1–3 cm high along the mid-back. There may be thick folds of blubber, especially along the ventral surface. There is an obvious neck, which is much more flexible and mobile than in other cetaceans. The head is rounded and tapered in calves, with only the slightest indication of a beak. The melon expands with age, creating a bulbous forehead and a more obvious short, broad beak. The flippers are broad, blunt, and flat, but develop a distinct upward curve on the lateral edge in adult males that can be used to differentiate sexes in the field. The flukes have convex trailing edges. Belugas’ most conspicuous character is their color—adults are completely snow-white. Calves are born dark slaty gray and gradually become lighter with age, becoming all white at the time of sexual maturity.

Natural history: Beluga whales are highly social and gregarious. They generally are seen in small groups of 2–10 animals, although sightings off the northeastern U.S. are usually single individuals. Belugas follow a distinct annual movement pattern. After the spring break-up of the sea ice, they move into summering areas in near-shore waters and in river mouths and estuaries. They frequently occur in extremely shallow water, sometimes barely deep enough to swim. They are apparently capable of swimming backwards, which may help them avoid being stranded by the out-going tide. One hypothesis for using shallow waters in summer is that water temperatures may warm more quickly, providing a thermoregulatory benefit to young calves. In addition, belugas are the only cetacean known to undergo an annual molt. In summer, the entire outer layer of the skin turns yellow and is sloughed off. During the molt, belugas are known to rub themselves on gravel bottoms in shallow water to help scrape off the old skin. In winter, belugas are thought to mainly move offshore with the ice edge, however satellite-tracked radio-tagging has shown them traveling long distances to as far as 1100 km offshore and as much as 700 km deep in the ice pack.

Belugas are capable of diving to the sea floor in much of their habitat. They routinely dive to 300–600 m and are capable of dives to more than 1000 m with durations up to 25 minutes. The diet of beluga whales is extremely broad, although little is known for the winter season. Prey species include benthic and demersal fishes such as flounders, cods, and sand lance; pelagic fish such as capelin, herring, and smelt; migratory fishes like salmon and eels; squid; octopus; shrimp; and benthic worms, clams, and crabs.

Calving takes place in a relatively short period in the summer, with the timing differing slightly between different stocks. Calving peaks in July in the St. Lawrence population. Calves average 1.6 m at birth. Mating takes place in the spring, and the gestation period is 14–14.5 months. Males attain sexual maturity at about age 8, and females around 5–6. Lactation lasts 20–24 months, with the calf beginning to feed on easily captured prey like crabs, worms, and mollusks during its second year. The inter-birth interval for most females is 3 years.

Historical and recent occurrence: Cronan and Brooks in The Mammals of Rhode Island reported no occurrences of belugas in Rhode Island, but stated that “there are records from New Hampshire; Cape Cod, Massachusetts; and Atlantic City, New Jersey; it therefore seems likely that the white whale may someday be seen off Rhode Island.” They turned out to be right about Rhode Island, although they were wrong about Atlantic City. There is a beluga skull in the Smithsonian collection labeled as “from Atlantic City,” however it came from a whale kept on display in a tank there, which had originally been captured in the St. Lawrence River.

Beluga sightings are rare in our region, but individuals who do appear stay for extended periods, usually near the coast. One might expect them more often north of Cape Cod, closer to home, and there was one group of six animals seen for two months in the vicinity of Portland, Maine in August and September 1927. The earliest reliable record south of Cape Cod was a beluga that was seen in Long Island Sound between Orient Point and Mattituck, New York, for four days in June 1942. Two animals, a white adult estimated at 4 m and a gray juvenile estimated at 3 m, were seen by divers off Avalon, New Jersey, on 17 July 1978. The adult was never seen again, but there were multiple sightings of a juvenile around southern New Jersey until September that year—probably all the same animal. In March 1979 a 3 m beluga was chased out of Jones Beach Inlet on the south shore of Long Island by the Coast Guard. It stayed around the area of Jones Beach and east to Fire Island Inlet through October. It might have been the same whale seen the year before in New Jersey. In 1979, there was also a sighting by an aerial survey on 5 July of a group of 3 belugas near the edge of continental shelf south of Hudson Canyon — the only offshore record in the region. In 1980, a single beluga was seen in Jones Beach Inlet and the channels behind the barrier island between 4 and 12 April, and a single beluga was seen off Moriches Inlet farther east along Long Island on 22 June. In 1981 along Long Island, a 3.35 m beluga stranded on 20 May on Gilgo Beach, and another was seen for four weeks beginning in mid-August around Fire Island Inlet. In February 1985, a beluga was seen in the harbor at New Haven, Connecticut. It was repeatedly sighted over succeeding months. On 13 May 1986 it was found dead and entangled in fishing gear in the Sound south of the harbor, however, the cause of death was determined to be from a gunshot wound. The most recent beluga whales in our region prior to this year were in 2003–4 and 2005. A juvenile whale, eventually nicknamed “Poco,” was sighted repeatedly between September 2003 and October 2004 along the New England coast from New Brunswick to Massachusetts. Poco was found dead on the shore near Portland, Maine in November 2004; a necropsy showed that the probable cause of death was infectious disease. Another animal occurred in the Delaware River and Delaware Bay in April 2005, swimming as far upstream as Trenton, New Jersey.

Coming next in Marine Mammals of Rhode Island: Harp Seal

Posted in Animals, Conservation, Education, Historical, Natives, Naturalists, News |

Invasive Emerald Ash Borer Beetle Detected in Boston

Emerald Ash Borer Credit: Marianne Prue, Ohio Department of Natural Resources - Division of Forestry, Bugwood.org

Emerald Ash Borer Credit: Marianne Prue, Ohio Department of Natural Resources – Division of Forestry, Bugwood.org

With emerald ash borer beetle (EAB) being detected in Boston it is virtually certain to be in Rhode Island by now. This has been some time coming, as the beetle has gradually expanded from its accidental introduction in the midwest in the late 1990’s. This beetle will be the end of wild ash trees in North America, and most ornamental ones, too, as only trees receiving constant systemic insecticide will survive.

Why so sure emerald ash borer is here? EAB is different from Asian longhorned beetle (ALB), that is also infesting right over the Mass. border. ALB is that other forest wrecker unwittingly imported among the packing materials of the orgy of Chinese imports we brought upon ourselves during the 1990’s. But ALB is a generalist feeder and so it’s dispersal mechanism doesn’t need to be very good (it’s leads an indolent lifestyle, shall we say), EAB is a specialist and it needs to be good enough at traveling to find new host plants even if they’re miles away (let’s call it an overachiever in the beetle dispersal world). That’s why the ALB infestation in and around Worcester, Mass., is worth fighting neighborhood to neighborhood whereas if EAB is in Boston we can expect it already to be in Rhode Island and there’s not much we can do about it. Here’s the text of an email sent out by the Mass. Department of Conservation and Recreation today:

Massachusetts State Officials Confirm Emerald Ash Borer Detected in Suffolk County

BOSTON -Wednesday, July 30, 2014 – The Department of Conservation and Recreation (DCR) and the Department of Agricultural Resources (DAR) today announced that the Emerald Ash Borer (EAB) has been detected in Suffolk County, Massachusetts. The destructive beetle was detected in a trap at the Arnold Arboretum on July 16, 2014, and was confirmed by federal officials on July 18. Suffolk County is the third county in the Commonwealth to have a confirmed detection of EAB.

DCR and DAR officials are working in collaboration with the United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) and the U.S. Forest Service to take a number of swift proactive steps aimed at slowing the spread of the invasive beetle, including:

. Defining a quarantine area that would only allow the movement of certain wood products under certain conditions;
. Conducting a delimiting survey to help identify the extent of the infestation;
. Working with stakeholders to ensure they know how to properly treat or dispose of infested trees and materials; and
. Maintaining a ban that has been in place against bringing any firewood into state parks and forests.

“The presence of Emerald Ash Borer in our state represents a serious threat to our ash trees,” said DCR Commissioner Jack Murray. “We are taking swift action to address the infestation, educate the public, and work to mitigate any impact an infestation could bring.”

“It is important for the public to remain vigilant and to report any ash trees with signs of Emerald Ash Borer damage,” said DAR Commissioner Greg Watson. “Early detection of new infestations will help slow the spread of this pest.”

In August of 2012, EAB was detected in Berkshire County in the Town of Dalton. In November of 2013, EAB was confirmed in Essex County in the Town of North Andover. DCR instituted county-wide quarantines of Essex and Berkshire counties shortly after the EAB was discovered. To date, 23 states across the country have confirmed detections of EAB. DCR has received $125,000 in funding from the USDA’s APHIS and $60,000 in funding from the U.S. Forest Service. DCR has also spent $185,000 to combat infestations of EAB.

Regulated items that would fall under quarantine include:

. The Emerald Ash Borer, in any living stage of development;
. Firewood of all hardwood species;
. Nursery stock of the genus (Ash);
. Green lumber of the genus (Ash);
. Other material living, dead, cut or fallen, including logs, stumps, roots, branches, and composted and uncomposted chips of the genus (Ash);
. Any other article, product or means of conveyance that an inspector determines presents a risk of spreading EAB and notifies the person in possession of the article, product or means of conveyance that it is subject to the restrictions of the regulations.

Emerald Ash Borer is a small, metallic green beetle, native to Asia, which feeds on ash trees. It was first discovered in North America in 2002, in the Detroit, Michigan area. Unlike many other invasive beetles, EAB kills ash trees quickly, within just 3 to 5 years, because it bores directly under the bark and disrupts the tree’s conductive system. Since its discovery in North America, it has killed millions of ash trees and has caused billions of dollars in treatment, removal and replacement costs to address the infested trees.

Ash is a main component of the northern hardwood forest in Massachusetts and is a common species in western Massachusetts. Ash is also a popular street tree in eastern Massachusetts.

“Unfortunately, tens of thousands of trees are needlessly killed by invasive tree-killing insects and diseases every year,” Andy Finton, Conservation Programs Director for The Nature Conservancy (TNC) in Massachusetts. “If everyone makes the commitment to take one simple step – not moving firewood when they travel or camp – we can work together as a Commonwealth to save both newly planted and already existing trees from being lost from our roadsides, backyards, and natural areas.”

Residents are urged to take the time to learn the signs of EAB damage which include:

. Tiny, D-shaped exit holes in the bark of ash trees, dieback in the upper third of the tree canopy, and sprouting of branches just below this dead area.
. In the winter months, signs of EAB infestation left by woodpecker activity on ash trees. Fresh, light-colored wood pecks stand out against the darker bark of the tree. Severe woodpecker activity at the base of the canopy or on the main stems may indicate possible EAB infestation and should be reported to state forest health personnel immediately.
. The Emerald Ash Borer is an emerald-green metallic beetle so small that seven of them could fit on the head of a penny.

DCR and APHIS will be scheduling listening sessions in Suffolk County in early September to provide the community with information relative to the finding and address questions. To report suspicious tree damage or insect sightings, or to learn more about this pest, visit http://massnrc.org/pests/eabreport.htm. You can also call the toll free EAB hotline at 1-866-322-4512.

In Rhode Island, if you find or suspect EAB, contact Rhode Island Department of Environmental Management, Gail Mastrati, 222-4700 ext. 2402.

Posted in Animals, Education, Invasives, News |

Marine Mammals of Rhode Island, Part 6, Sperm Whale

by Robert D. Kenney

In a previous installment of “Marine Mammals of Rhode Island” we looked at the harbor porpoise, our smallest cetacean. We now turn to one of the largest—the sperm whale. Both species are toothed whales, or odontocetes; in fact the sperm whale is the largest of the world’s toothed whales. The toothed whales includes a variety of species known as whales, dolphins, and porpoises, characterized by having teeth in one or both jaws (although in some species teeth only erupt in adult males) and a single blowhole or external nostril. They use echolocation for navigation, foraging, and sometimes communication, producing mid- to high-frequency “clicks” and listening to the echoes. Many species also produce tonal sounds, most often referred to as “whistles,” however neither harbor porpoises nor sperm whales are known to whistle. Sperm whales are the only toothed whales large enough to be included with the baleen whales among the so-called “great whales.” They were the basis of Yankee whaling in the 18th and 19th centuries as memorialized in Melville’s classic Moby Dick.

Sperm whale illustrations from Richard Lydekker (1895) The Royal Natural History. Frederick Warne & Co., London and New York.

Sperm whale illustrations from Richard Lydekker (1895) The Royal Natural History. Frederick Warne & Co., London and New York.

Sperm whales are listed as Endangered under the U.S. Endangered Species Act, are not included on the Rhode Island state list, and are classified as Vulnerable on the IUCN Red List. The IUCN’s analysis concluded that a lower Near-Threatened classification was almost as well-supported, and that a higher Endangered status could be rejected. There really are no reliable estimates of the global abundance of sperm whales; the range could be from perhaps 200,000 to over 2 million. A few thousand sperm whales are estimated to live off the east coast of the U.S. and in the Gulf of Mexico, but those estimates are minimum values because surveys do not cover the entire oceanic range of the population, and because many whales are never seen during surveys due to their very long dives.

Hundreds of thousands of sperm whales were killed worldwide since the beginning of Yankee whaling in the early 18th century. Commercial hunting of sperm whales ended worldwide in 1986. There is presently no hunting at all in the North Atlantic, and a few are taken each year in the North Pacific under scientific research permits by the Japanese. Sperm whales are occasionally entangled in fishing gear off the east coast of the U.S. or struck and killed by ships, but the level of mortality is not believed to be biologically significant. There is also concern that sperm whales could be subject to negative impacts from increasing levels of noise in the oceans, from sources including shipping, naval sonar, and seismic exploration for oil and gas.

The carcass of a sperm whale calf awaiting burial on the GSO beach in 1967.

The carcass of a sperm whale calf awaiting burial on the GSO beach in 1967.

Sperm whales are mainly found far offshore, and strandings along the Atlantic coast are relatively rare. The only known stranding in Rhode Island was in Charlestown in February 1967. It was a calf, measuring just over 14 feet long. The carcass was buried on the beach at the URI Bay Campus, with the hope of recovering the skeleton some time later. This past winter, several test holes dug by a back-hoe at the probable grave-site failed to find any sign of whale bones.

Description: In addition to being the largest toothed whales, sperm whales are the most sexually dimorphic of all cetaceans. Adult males may reach 18–20 m in length, while the maximum size for adult females is only 12.5 m. More typical adult sizes are 12–16 m in males and 8.5–11 m in females. The head is large and blocky, with a very narrow lower jaw. Large teeth in the lower jaw fit into sockets in the roof of the mouth. The blowhole is S-shaped and located on the forward left corner of the head, producing a blow with a distinctive slant. The body color is gray-brown, often with lighter areas on the belly and around the mouth. The skin is smooth on the head, but forms longitudinal wrinkles on the rest of the body. The flippers are relatively short and rounded. The dorsal fin is low, blunt, and triangular, and there are distinct “knuckles” on the ridge between the dorsal fin and the tail. The skull has a broad, flat rostrum and a large concavity in the facial region—“Neptune’s chariot” to the Yankee whalers. The large space in the forehead above the skull is occupied by the spermaceti organ, whose function is not entirely understood but is likely involved in both echolocation (focusing the outgoing clicks) and hydrostatic balance (adjusting density to maintain vertical position in the water column)

Natural history: Sperm whales are found from tropical to sub-polar waters in all oceans of the world. In the western North Atlantic, they occur from the edge of the pack ice south to the Gulf of Mexico and Caribbean. Mature males penetrate farther into high-latitude waters than females or immatures, with the northern distributional limit of female/immature schools in the western North Atlantic probably around Georges Bank and the Nova Scotian shelf.

Most sperm whale sightings around the world are in waters deeper than 200 m, however significant numbers of sightings have occurred in shallow continental shelf waters south of New England and on the Nova Scotian shelf. They occur year-round off the northeastern U.S., but with some seasonal variability. Most sightings have been along the shelf break and the edge of the Gulf Stream, but there has been little or no survey effort farther seaward, and sperm whales can probably occur almost anywhere in the deep ocean.

Like most toothed whales, sperm whales are very social and live in permanent matrilineal groups. Typical group sizes seen during our surveys were 2–10 whales. The basic unit of sperm whale social organization is the “mixed school” consisting of females of all ages and immature males. Mixed schools are predominantly female, 70% or more. Adult females in the school are closely related, and the calves and immatures of both sexes are their offspring. Females in the mixed schools remain associated for their entire lives, while males leave the mixed schools and form “bachelor schools.” Whalers assessed the size of a whale based on the oil yield. One New Bedford whaling captain indicated that the largest adult females or bulls in mixed schools yielded 35 barrels of oil. Bachelor bulls were caught in schools of same-sized animals, which decreased in number as the whales got larger. The largest bachelor schools were the 40-barrel bulls, and the next largest the 50-barrel bulls. Schools of 60-barrel bulls were generally 8–10 whales, 70-barrel bulls were in schools of 4–5 whales, and larger bulls were solitary or in pairs or trios.

Sperm whales are at the extreme end of the baleen vs. toothed whale dichotomy in life history—growing, maturing, and reproducing slowly. Single calves are born at 4 m long following a gestation of 14–18-months. In the Northern Hemisphere, mating occurs from December to August with a peak in March–May. Large dominant bulls rove from one mixed school to the next. Adult females in a mixed school tend to come into estrus synchronously, and a bull’s stay might only be a few hours. Calves nurse for at least two years, and sometimes much longer, but begin feeding on solid food at about a year old. Females reach sexual maturity at age 7–13 and at about 9 m long. Growth then slows until they reach maximum size at about age 30. Maturation in males is a prolonged process, beginning at about age 10 and lasting for 10 years. They continue to grow at a more rapid rate than females, and do not reach their full size and complete physical maturity until about age 50. Males generally do not begin breeding successfully until their late twenties. The interval between calves for prime-age females is about 5 years.
Sperm whales are prodigious divers. Dives typically last 30–40 minutes, but dives lasting an hour or more are relatively common, and there is a published report of one dive of 2 hours and 18 minutes. Average dives are to about 400 m, but dives deeper than 2000 m are known.

Diving sperm whales click regularly once or twice per second as they search for prey. It sounds like a hammer on a board, and I learned to call that sound “carpenter fish” during my Navy days listening for Soviet submarines. The whales in the school can certainly hear each other as they spread out during foraging dives, and they may be using clicks at the same time as contact calls. There are occasionally accelerating series of clicks (“creaks” or “buzzes”) as a whale homes in on a prey item. Socially interacting whales also produced patterned sequences of 3 to about 20 clicks called “codas”. Codas vary by region and between schools and are probably passed on culturally within matrilineal groups. There are also very loud and slow (6–8 seconds apart) clicks called “clangs” that appear to be produced by large males; their function is not clear.

The primary prey of sperm whales is squid, including many different species. While they do eat giant squid, the majority of the diet consists of medium-sized squids with mantle lengths of 20 cm to 1 m. Medium to large near-bottom fishes, including rays, sharks, and a variety of bony fishes, comprise small portions of the diet in most regions, but may be the predominant prey in certain areas, especially in high latitudes where only male sperm whales tend to occur. Other prey items include benthic octopus, crabs, and other crustaceans. Feeding occurs at depth, apparently all the way to the bottom at times, since stomach contents sometime include stones, sediment, shells, and other non-food items from the sea floor.

Historical occurrence: There are few specific records of sperm whales in Rhode Island or our neighboring states, mainly because they mostly occur far from shore. They were probably rarely, if ever, taken or even seen by the shore-based Long Island right whalers. The tale, likely apocryphal, is that Yankee sperm whaling began in about 1712, when Capt. Christopher Hussey, while hunting right whales from Nantucket, was blown offshore in a storm and took the first sperm whale. The sperm whale fishery expanded greatly, with voyages from a number of southern New England ports including Sag Harbor, Long Island; New London and Stonington, Connecticut; several localities in Rhode Island; and Nantucket, Woods Hole, and New Bedford, Massachusetts. Most of the historical information pertains to sperm whales landed at those whaling ports. In addition to the 1967 Charlestown stranding, other historical inshore records for our neighboring states included, for New York—a calf stranding at East Hampton in March 1891, a 12-m whale captured in Fishers Island Sound in December 1894, and a stranding on Fire Island in February 1918; and for Massachusetts— a stranding at West Yarmouth in June 1954 and one at Nantucket in September 1961.

Aggregated sighting, stranding, and bycatch records of sperm whales in the Rhode Island study area, 1891–2004 (n = 103: winter [blue] = 8, spring [green] = 17, summer [red] = 59, fall [brown] = 19).

Aggregated sighting, stranding, and bycatch records of sperm whales in the Rhode Island study area, 1891–2004 (n = 103: winter [blue] = 8, spring [green] = 17, summer [red] = 59, fall [brown] = 19).

Recent occurrence: The distribution of sperm whales in the Rhode Island study area is concentrated along the edge of the continental shelf, with 57.3% of the records in the summer, 18.5% in fall, 16.5% in spring, and 7.8% in winter. Southern New England is one of the rare locations in the world where sperm whales occur frequently well inshore of the shelf break. Sightings on the shelf in waters shallower than 200 m occurred in all four seasons, including seven sightings in summer, three in spring, and one in fall from whale-watching boats. Many of them are aggregated in a relatively narrow band extending north-south along the shelf valley offshore of Montauk Point and Block Island. It is often speculated that sperm whale occurrence in shelf waters corresponds with inshore movements of spawning squid.

Posted in Animals, Historical, Naturalists, News |

Marine Mammals of Rhode Island, Part 5, Harbor Seal

by Robert D. Kenney

In our report for the Rhode Island Ocean Special Area Management Plan, we showed that 36 species of marine mammals had been recorded in our estuarine and marine waters, and a few others were possibilities. Despite what might seem to some to be a surprisingly high diversity of species, only one of those species can truly be called a resident of Rhode Island—the harbor seal (known as the common seal in Europe). Harbor seals are the only marine mammal in the state where you can go to a particular location at a particular time and be reasonably confident of seeing wild marine mammals in their natural habitat. In fact, one of the “memorable events” we have planned to celebrate the R.I. Natural History Survey’s 20th anniversary is coming up on April 26th—a program on seals that includes a walk out to the largest known harbor seal haul-out in the state (visit the 20 Memorable Years webpage or the Facebook page for more details).

HASE1Seals are pinnipeds (“wing-foots”). Pinnipeds are marine mammals that are characterized by retention of all four limbs as flattened, simplified flippers. They are grouped into three families: the seals, the sea lions and fur seals, and the walrus. Pinnipeds are not as completely adapted to life in the ocean as are whales or dolphins, since all species must leave the water to give birth, either on land or on sea ice. Although Pinnipedia was once classified as a separate Order of mammals, recent evidence shows that they belong within the Order Carnivora (lions and tigers and bears, oh my!)—more closely related to the dog-like branch than the cat-like branch of the carnivore family tree.

The population status of the harbor seal is believed to be relatively secure. They are not listed under the U. S. Endangered Species Act or on the Rhode Island state list, and are classified as Least Concern on the IUCN Red List. The harbor seal population in New England has grown significantly since they were protected by the passage of the Marine Mammal Protection Act (MMPA) in 1972. Mike Payne and Larry Selzer from the Manomet Bird Observatory in Massachusetts counted harbor seals between the Massachusetts-Rhode Island border and eastern Long Island Sound in the late 1980s and found only a few hundred. Only Fishers Island, New York consistently had more than 50 animals, with a peak of 101 in March 1986. In contrast, my graduate student Cheryl Schroeder estimated that the total number present in Narragansett Bay alone in 1999 was between 825 and 1,047. Dr. Jim Gilbert from the University of Maine has periodically counted seals hauled out on ledges along the entire Maine coast from aerial surveys. Between 1981 and 2001, seal counts increased from 10,543 to 38,014 (6.6% per year), and pup counts increased at an even higher rate of 14.4%.

Harbor seals were hunted by Native Americans for subsistence, then by early European settlers for oil, meat, and leather. In recent times, commercial hunting has never been of any great importance, but seals are commonly perceived as competitors for commercially valuable fish stocks. Bounties were paid on harbor seals in both Maine and Massachusetts into the 1960s, resulting in depletion of the population overall and its extirpation from pupping sites in Massachusetts. Harbor seals were also hunted for sport in the U.S. prior to passage of the MMPA. Strandings in Rhode Island are relatively common, averaging around 6–10 each year since 1990.

Harbor seals are taken as by-catch in a variety of U.S. and Canadian commercial fisheries, including gillnets, drift nets, long-lines, bottom trawls, midwater trawls, purse seines, trammel nets, fish traps, herring weirs, and even lobster traps. The most recent 5-year (2007–20011) estimate of average numbers of harbor seals killed annually in U.S. Atlantic fisheries was 407, mostly in gillnets. Other known sources of human-related mortality in the northeastern U.S. and Canada include boat strikes, entrainment in power plant intakes, entanglement in aquaculture facilities, and intentional shooting.

More is known about disease as a population impact for harbor seals than for other marine mammals. A relatively large number of diseases is known, and there have been several significant epizootics. At least 500 harbor seals died from Mycoplasma bacterial pneumonia in New England in 1979–80. The epizootic began in Cape Cod Bay in December 1979 and spread north along the Maine coast. The seals that contracted pneumonia were also infected with a strain of influenza A, and the hypothesis was that the influenza lowered their immune response to the Mycoplasma. There was a second, smaller epizootic in 1982 that killed only about 60 animals, which began in Narragansett Bay and was caused by a different strain of influenza A virus that normally is found in birds. And another influenza/pneumonia epizootic killed about 160 New England seals, mostly pups, in late 2011. Another virus that infects seals is phocine distemper virus (PDV), which was implicated in the deaths of about 18,000 harbor seals in Europe in 1988. PDV appears to be present in harbor seals in New England, but in most years does not cause increased mortality or even recognizable disease symptoms.

Description: Seals and sea lions differ in a number of anatomical characteristics, with the walrus often intermediate. Sea lions possess external ears, which are absent in seals and walrus. Seal flippers are completely furred with well-developed claws. The hind-flippers are oriented directly backwards with opposed soles, and cannot be rotated underneath the body for locomotion on land, which is accomplished by caterpillar-like wriggling. In water, seals swim via alternating, lateral strokes of the hind-flippers, while using the fore-flippers mainly for maneuvering. Sea lions have longer and at least partially furless flippers. The pelvis and hind limbs can rotate underneath the body for walking on land. In water, they swim by simultaneous flapping of the long fore-flippers and use the hind limbs more as rudders. Walruses walk like sea lions and swim like seals. Seal coats have little underfur, and a seal is insulated by a thick layer of blubber. Fur seals have dense underfur for thermal insulation and the least developed blubber layer, while sea lions have less dense underfur and moderately thick blubber.

Aggregated sighting, stranding, and by-catch records of harbor seals in the Rhode Island study area, 1954–2005 (n = 507: winter [blue]  = 158, spring [green] = 266, summer [red] = 48, fall [brown] = 35).

Aggregated sighting, stranding, and by-catch records of harbor seals in the Rhode Island study area, 1954–2005 (n = 507: winter [blue] = 158, spring [green] = 266, summer [red] = 48, fall [brown] = 35).

Harbor seals are relatively small animals, with adults 1.7–1.9 m long. Males are slightly larger than females. Harbor seals vary in color from very light gray or tan to brown to almost black, with extensive spotting. The basic spotting pattern is light with dark spots. In some individuals the spots coalesce, particularly on the back, giving the appearance of a dark color with sparse, light mottling. In general the belly is lighter than the back. Whether an individual is wet or dry will greatly change its appearance, with completely dry individuals often appearing light-colored. Pups shed their white fetal coat (lanugo) in utero and are born with the same spotted coat pattern as adults. A harbor seal has a rounded head with a concave puppy-like face and only a short distance from eyes to nose. The nostrils are close together at the bottom and look like the letter “V” when seen from head-on.

Harbor seal haul-outs in Rhode Island: 1966–1976, 1981, 1986–1987, and 1994–1999 (based on Schroeder, 2000, M.S. thesis).

Harbor seal haul-outs in Rhode Island: 1966–1976, 1981, 1986–1987, and 1994–1999 (based on Schroeder, 2000, M.S. thesis).

Six haul-outs were identified in Narragansett Bay in the 1980s, with peak counts of 43 at the Dumplings off Jamestown and 36 at Rome Point in North Kingstown. The numbers of harbor seals in Rhode Island have increased dramatically since then. Cheryl Schroeder reported 21 haul-outs around Narragansett Bay during 1994–1999. The largest haul-out was a clump of rocks located less than a quarter-mile off Rome Point, with a maximum count of 170 animals. She also identified six harbor seal haul-outs at Block Island, collaborating with Scott Comings of The Nature Conservancy. The largest is at Cormorant Cove in the southwestern corner of Great Salt Pond. The other five are around the periphery of the island.
In Rhode Island, seals utilize different haul-out types around Narragansett Bay compared to those on Block Island. Nearly all of the haul-outs around the Bay are rocky ledges and isolated rocks that are mostly submerged at high tide. The exception is Spar Island, which is a man-made dredge-spoil island in Mount Hope Bay. At Block Island, there are several haul-outs on cobble and sandy beaches around the island, but the haul-out used by the largest number of seals is a wooden raft moored in Cormorant Cove, often used by 50 or more seals.

Coming next in Marine Mammals of Rhode Island: Harp Seal

Posted in Animals, News, Uncategorized |

Meet the Board: Pete August

To put more of a face on the Natural History Survey, we are including profiles of board members, staff, and members among our Rhode Island Naturalist blog posts. This time the celebrity treatment goes to Pete August, Rhode Island’s bat-man and GIS pioneer.

Pete August was the first president of the Rhode Island Natural History Survey, having helped establish the organization 20 years ago, but he didn’t discover his interest in natural history until much later than most biologists. He admits he wasn’t very good at chemistry and physics in high school, but somehow he knew he wanted to work in the sciences in some capacity, so he randomly selected biology as his major at the University of San Diego. It was a good decision.

Pete August

Pete August

“I responded to a professor’s request for someone to help with a project surveying mammals and reptiles in a bioreserve called Bolsa Chica,” he recalls. “I carried traps and did all the grunt work and thought, here we are camping in a beautiful place by the ocean, studying interesting animals, and people get paid to do this. Sign me up!”

From that point forward, he has focused his career on mammalogy, field ecology and environmental conservation. As a graduate student, he went to Venezuela to study rodents and marsupials, but expanded his focus to include bats soon after he got there.

“Rodent trapping can be slow in the tropics with 100 traps yielding only a capture or two. But when the fig trees had ripe fruits, the night sky would become alive with bats,” Pete said. “I put up my first mist net and caught hundreds of individuals. There were always 30 bats of a dozen or so species in my net. Studying bat ecology was a lot more fruitful data-wise than rodents and marsupials.”

That work eventually led him to the University of Rhode Island, where he has been a professor on the faculty since the early 1980s. A short project he conducted with the Illinois Natural History Survey introduced him to the use of Geographic Information Systems (GIS) in wildlife conservation, which inspired him to apply for a grant to build the first GIS system in Rhode Island.

“GIS intrigued me because a lot of my rodent ecology work required mapping and measuring habitats in my study areas, and doing calculations of areas and distance was always a pain,” said Pete. “Part of the promise of GIS is an electronic mapping system that allows you to consolidate all kinds of information and to accurately measure spatial patterns. I knew this was going to be useful in my work with ecology and conservation.”

A long-time member of the boards of the Rhode Island chapter of the Nature Conservancy, the Wood-Pawcatuck Watershed Association and the Richmond Land Trust, Pete said that the theme of much of his work throughout his career has been using computer technology to help conserve biodiversity.

His guiding motivation for helping to establish the Rhode Island Natural History Survey, on the other hand, was a bit simpler than that. “There was no consistent, predictable venue for the state’s naturalists to meet and talk and compare notes,” he said, “so we formed the Survey to create that forum to bring together Rhode Island’s naturalists. And it has worked. The thing I’m most proud of is that it has persisted, and it has persisted because of the leadership and commitment of Lisa Gould (the Survey’s first executive director) and David Gregg and Kira Stillwell and the officers that we’ve had since that first moment in the early 1990s.

“What’s so interesting to me is how clear we were from the very beginning about our mission,” he added, “and how successful we’ve been at meeting that mission: to provide a forum to exchange information about natural history. We do that through the lecture series, conferences, BioBlitz and all sorts of other things that we never even anticipated in those early days.”

Posted in Animals, Biodiversity, Conservation, Historical, Naturalists, News |

Exec’s Blog: Global Warming, Eek!

[I originally published this in January 2008. I thought in honor of today’s low temperatures I’d resurrect it from the back of the blog roll. Enjoy! -DWG]

by David W. Gregg, Executive Director, RINHS

Today’s Exec’s Blog is about global warming and is RINHS’s contribution to Focus the Nation.

blizzard1I grew up in New England, around Boston and then on Cape Cod, and I have loved living in New England because of the winters. No, not for the way ten inches of new powder snow muffles the village green, nor the way the skaters congregate on the neighborhood pond, nor the tangy smell of hardwood smoke lying under the temperature inversion along the valley floor. After all, I said, “Cape Cod.” Think driving sleet instead of snow, crackling deathtraps instead of solidly ice-covered ponds, and acrid smoke of fires “burning” wet oak instead of mouthwatering maple, hickory, or butternut. No, it’s not for the Currier & Ives aesthetics that I love New England winters: I love New England winters because they reset the bugs once every 12 months.

Once you get them going, arthropods (insects, spiders, chilopoda, mites, et al.) have a tendency to just keep going unless and until they run into something that stops them. As long as conditions are favorable, they’ll keep on eating, growing, and breeding. For arthropods, favorable conditions are warm and humid, with lots of leafy, bushy, grassy vegetation to provide food and shelter. So very generally speaking, for any particular region the size and population of crickets, spiders, centipedes, mosquitoes, and what not is more or less determined by how much eating, growing, and breeding can be fit in between last frost and first frost. If that’s a short time, you have small bugs and not so many of them and if that’s a long time, you have lots of bugs, they’re giants, and they have plenty of time left over after securing life’s bare necessities to explore the insides of your home. It’s a bit more complicated than that, of course. For instance, arthropods’ growth and reproduction isn’t just on or off, its rate can rise and fall with temperature so a long, cold summer can be as limiting as a short, hot one. Also, you’ll probably have noticed that the short, cold summers of the Arctic don’t seem to slow down the mosquitoes any. But generally, the arthropod fauna in an area is temperate if the climate is temperate or tropical if the climate is tropical.

These same general observations apply to plants (and to rodents) as they do to arthropods. In the same way that a painter brings light into a painting by using dark, frost makes it possible for us to have variety in our flora…spring ephemerals, summer perennials, fall foliage. As with insects, frost either limits a plant’s size to the growth of one season or forces it to be woody so it can over-winter (which just makes it useful for things like firewood). A good, hard frost is truly the Great Equalizer. Without a good, hard frost animals and plants would treat winter like intermission…pop out for a pee break and some popcorn then back in for the second act!

And that’s where global warming comes in. If I wanted to live in a part of the country where giant crickets were a regular part of my kitchen’s fauna and I had to deal with six species of blood-sucking Acari (mites and ticks) when I went outside, I’d move to North Carolina. I’ve learned to live with SOME ticks and I like my hymenoptera small and manageable. I don’t want to live with chiggers or fire ants or malaria mosquitos or killer bees. Frost has protected us New Englanders from these things and from kudzu and God knows what. And yet with global warming, all these creatures and more have just got their tickets punched for an express trip to a quaint New England village. Doubt it? Have you experienced a swarm of lone star tick larvae, a new addition to our tick diversity now making their way along the coast?

All this interest in keeping the bugs down may seem pretty strange coming from someone with a professed avocation in insects, but there you are. Maybe I like my Nature just a little bit buttoned down, and as long as it’s Mother Nature herself who does the buttoning, then I’d say it’s a defensible sentiment. But what if we mess with Mother Nature’s natural reset button, as we seem to be with global warming? SHE’s not the one who’s going to care. She’ll just keep going with the insects and the mites and the ants and the vines. WE’RE the ones who’ll have to move north or learn to love our new environment…”Oh look, honey, the fire ants got the dog!”

Posted in Climate, News |

Snowy Owl Invasion

by Todd McLeish

Photo: Carlos Pedro

Photo: Carlos Pedro

Snowy owls aren’t often found in significant numbers in Rhode Island. They usually spend all year in the Arctic feeding on lemmings on the tundra. But occasionally, when the lemming population crashes or the owl population spikes, many of the large white birds migrate south in winter in search of food. This is one of those years.

Throughout the Midwest and Northeast, snowy owls have been showing up this winter in numbers not seen in decades. Most often, they are found on beaches, farm fields, and airports, which mimic their tundra homes, where they search for mice and voles. In Rhode Island, the owls are being seen regularly since late November at Sachuest Point National Wildlife Refuge in Middletown and at Misquamicut and Moonstone beaches in South County. Others have been sighted in Jamestown, Warwick, Providence and elsewhere, including locations along Route 95. Several injured birds have also been found and are being rehabilitated. No one knows how many individual snowy owls are in the state this winter, but it is likely to be at least a half dozen, and probably more. For several days this month, three were spotted perched together on a rock at Sachuest.

Unlike so many other rare birds that occasionally visit our area, snowy owls are easy to identify. As former RINHS President Peter Paton told Rhode Island Public Radio recently, “It’s a majestic species. They stand over two feet tall and they have a four foot wingspan. So they’re an exciting species to see for us.” Weighing in at about six pounds, snowy owls are the heaviest owl species in North America. And their white plumage makes them unmistakable in our area. Adult males may be pure white, the perfect camouflage for a bird that spends much of its life in a snowy environment. Younger birds are much more visible, with contrasting gray barring on their white bellies and wings that make them stand out as they perch on fence posts, beaches and snow-covered fields.

If you decide to go in search of one of the snowy owls in the area, bring along binoculars or a spotting scope. The birds can be skittish and may fly off if you get too close. And stay quiet and don’t make sudden movements that may frighten them. The owls are already rather stressed after their long migration and their efforts to find food in unfamiliar places, so we don’t want to add to their stress.

If you’ve never seen a snowy owl before, now is the time to make the effort. You may never have a better chance.

Posted in Animals, Conservation, News |

Marine Mammals of Rhode Island, Part 4, Harbor Porpoise

by Robert D. Kenney

The porpoises are six species of small toothed whales within one family—closely related to the dolphins. The harbor porpoise is the smallest cetacean, and the only porpoise species, that occurs in the North Atlantic. When I was a graduate student, I worked on a project called the Cetacean and Turtle Assessment Program, or CETAP, which involved hundreds of hours of aerial surveys between North Carolina and Nova Scotia. From an airplane flying at 750 feet above the water, a harbor porpoise looks very tiny indeed. The only sure way to tell that you aren’t looking at a tuna or some other big fish is that the tail moves up-and-down instead of side-to-side. They looked so small that some of the aerial survey team took to calling them “sea hamsters.”

Harbor porpoise illustration from Frederick W. True (1889) Contributions to the Natural History of the Cetaceans; A Review of the Family Delphinidae. Bulletin no. 36. U. S. National Museum.

Harbor porpoise illustration from Frederick W. True (1889) Contributions to the Natural History of the Cetaceans; A Review of the Family Delphinidae. Bulletin no. 36. U. S. National Museum.

Harbor porpoises are relatively common, are not listed under the U.S. Endangered Species Act, and are classified as Least Concern on the IUCN Red List. A proposal was made by NOAA Fisheries in 1993 to list the Gulf of Maine/Bay of Fundy population as Threatened because of excessive by-catch mortality in the sink-gillnet fishery, but it was withdrawn in 1999 after an extensive review determined that the listing was not warranted. Northwest Atlantic harbor porpoises are listed as Special Concern under the Species at Risk Act in Canada. The total number of harbor porpoises in the North Atlantic is likely to be over 500,000, and the estimate for the Gulf of Maine/Bay of Fundy stock is around 80–90,000.

Harbor porpoises have been hunted in many areas around the North Atlantic for oil and meat for at least hundreds of years and probably much longer, but the practice continues today only by Inuit subsistence hunters in the Arctic. A much greater concern is mortality of harbor porpoises as by-catch in commercial fisheries, especially in sink-gillnet fisheries. The first U.S. government fisheries report in 1886 described the efficiency of gillnet fishing for cod, but also reported incidental captures of harbor porpoises. Since the U.S. marine mammal stock assessment program began in 1995, hundreds of harbor porpoises have been drowned in gillnets off the East Coast every year—over 2,000 in some years. A Take Reduction Plan is in effect in U.S. Atlantic waters (http://www.nero.noaa.gov/protected/porptrp), involving fishery closures in specific areas at times when the probability of porpoise by-catch is high, plus a requirement for the use of acoustic alarms (“pingers”) to alert porpoises to the presence of gear. By-catch mortality has declined somewhat, but not enough. Because of high porpoise mortality in gillnet fisheries off Rhode Island and southern Massachusetts, the Plan includes a “Cape Cod South” closure area that extends from 71°45′ W (approximately the longitude of Weekapaug) east to 70°30′ W (eastern Martha’s Vineyard), and from the shoreline south to 40°40′ N (a little over 50 km south of Block Island). Gillnet fishing is prohibited completely in March, and is allowed in December–February and April–May only using nets with “pingers.”

Harbor porpoises are the most common stranded cetacean in or near Rhode Island. Fishery-related mortality is likely to be a significant factor. Over a quarter of the porpoise strandings where a cause of death could be determined showed evidence of fishery interactions (e.g., rope or net marks). In another 18%, the animals were judged to be emaciated and most likely were newly weaned calves that were unsuccessful at feeding independently.

Description: Porpoises differ from dolphins in several characters. Porpoises have small but robust bodies with relatively small flippers and dorsal fins—all likely related to conservation of heat for a relatively small animal living in cold water. Porpoises have conical heads without pronounced beaks. The front part of the skull is much shorter than in small dolphins, and there is a pair of rounded knobs on the skull just in front of the braincase. Porpoise teeth are small and “spatulate” (flattened and curved, like tiny shovels) rather than conical as in dolphins.

Harbor porpoises are the smallest cetaceans occurring in the North Atlantic, reaching only 1.4–1.9 meters long. Females tend to be somewhat larger than males. The average adult female is 160 cm and 60 kg, an average male is 145 cm and 50 kg, and the largest individual known was a 200-cm, 70-kg female. The body is stocky, dark gray to black on the back and white on the belly with little or no distinctive patterning. The sides may be mottled or simply fade gradually from dark to light. There are often one or more dark stripes from the corner of the mouth to the flipper, and some may show darker eye, chin, and lip patches. The flippers are small and pointed, and the dorsal fin is small and usually triangular.

Natural history: Harbor porpoises are known from cool temperate to subpolar regions around both the North Atlantic and North Pacific, most often in relatively shallow continental shelf and coastal waters. They exhibit a clear seasonal pattern of distribution and movement, however there is little evidence for a coordinated annual migration. Off the Northeast, they are most concentrated in the northern Gulf of Maine and Bay of Fundy in the summer, and show up in the mid-Atlantic in winter. Adults may winter farther offshore than younger animals. Strandings are widespread from Maine to North Carolina.

Porpoise life histories are more like those of baleen whales than those of dolphins and other toothed whales. They mature quickly, grow rapidly, have short intervals between calves, and do not form permanent social groups. The most common harbor porpoise sighting off the northeastern U.S. is a single individual, with pairs and trios common. Occasional sightings of groups of 6–10 or even larger are most likely short-term associations, probably in areas of abundant prey. Reproduction is strongly seasonal, with most calves born in May in the Gulf of Maine. Gestation lasts 10–11 months. Calves are about 75 cm long and weigh about 6 kg at birth, and triple their weight in about 3 months. Lactation lasts at least 8 months, but weaning is gradual and calves begin feeding independently well before being completely weaned. Most Gulf of Maine females mate soon after giving birth, resulting in simultaneous pregnancy and lactation and 1-year intervals between calves. Females typically reach sexual maturity at 3–4 years of age.

Harbor porpoises primarily feed on fish and secondarily on squid and crustaceans. They prefer non-spiny fishes with relatively high fat content that are less than 40 cm long (usually 10–30 cm). Their primary prey species in the Bay of Fundy are herring and silver hake. Other commonly eaten species include anchovies, sprat, sardines, and capelin, and calves apparently begin feeding on small crustaceans.

Historical occurrence: Historical accounts of harbor porpoises in southern New England must be treated with some skepticism because the word “porpoise” has been applied commonly to dolphins, even into the 1950s and 1960s. James E. De Kay in 1842 reported that porpoises were “formerly so abundant on the shores of Long Island as to have induced the inhabitants to form establishments for their capture,” but his account was second-hand—based on a 1792 report describing a net fishery in eastern Long Island taking porpoises for oil and leather. More recent studies concluded that the fishery was not for harbor porpoises, but was most likely for bottlenose dolphins (see the previous entry in this blog series Marine Mammals of Rhode Island).

In The Mammals of Rhode Island (Cronan and Brooks 1968), the authors knew of no records of harbor porpoises in Rhode Island, but did mention occurrences nearby in Mount Hope Bay in July 1931 and September 1934. In the Smithsonian database there is a record of a stranding at Brenton’s Point in Newport on 5 July 1901 and another undated specimen record from Newport, both collected by Major E.A. Mearns. There are also records of a 119-cm, 26-kg porpoise stranded at Narragansett Pier in February 1972, and 139-cm animal stranded on First Beach in Newport in March 1976. There are multiple historical stranding and capture records from New York and New Jersey, and a few from Connecticut and Massachusetts. The earliest harbor porpoise record in our region was a report of a porpoise taken more than 30 km up the Connecticut River in Middletown, Connecticut in 1850.

Recent occurrence: Harbor porpoise occurrence in Rhode Island and nearby is strongly seasonal, with 69.5% of all records in spring, followed by winter (19.5%), summer (7.8%), and fall (2.7%). This follows what we know of the population’s seasonal cycle—we see harbor porpoises most often when they are returning from farther south and offshore in the spring, heading for the Gulf of Maine. Sightings are widespread across the shelf. They probably also occur in winter in Narragansett Bay, although we have only second- and third-hand anecdotal reports for evidence. Strandings have occurred all along the south shore of Long Island, along both sides of Long Island Sound, and in parts of coastal Rhode Island. Seasonal stranding frequencies do not quite match the sighting frequencies; they are highest in winter and second-highest in spring. Winter sightings are almost surely biased low—they are hard to see to begin with (small, mainly solitary, and tending to avoid vessels), winter conditions make that even more difficult, and there are many fewer observers on the water in the winter.

Aggregated sighting, stranding, and by-catch records of harbor porpoises in the Rhode Island study area, 1850–2007 (n = 376: winter = 73, spring = 262, summer = 29, fall = 10, unknown = 2).

Aggregated sighting, stranding, and by-catch records of harbor porpoises in the Rhode Island study area, 1850–2007 (n = 376: winter = 73, spring = 262, summer = 29, fall = 10, unknown = 2).

Coming next in Marine Mammals of Rhode Island: Sperm whale

Posted in Animals, Biodiversity, Historical, News |

Review: The Kingdom of Rarities by Eric Dinerstein

by Emilie Holland

[Author Eric Dinerstein spoke at the Natural History Week reception, November 8. RINHS has a limited quantity of this book available for purchase at $25, including tax and shipping (which is cheaper than Amazon). Contact the office to take advantage of this great holiday gift opportunity.]

Rarities book coverThe Kingdom of Rarities, by Eric Dinerstein, is an exploration of the meaning, causes, and impact of “rarity” on ecology at many scales. This book is global in scope, and its stories are told against the backdrop of a personal travelogue by the Chief Scientist of the World Wildlife Fund. With stops in the Chitwan National Park of Nepal, the Fojas Mountains of New Guinea, Amazonian Peru, the Brazilian Cerrado, Indochina, Bhutan, Hawaii, and Grayling, Michigan, Eric Dinerstein gives the reader a primer on current concepts in population biology and community ecology. He goes on to provide an ethical framework in which to consider policy questions relating to fate of rare, and potentially rare, species around the globe. Dinerstein’s accessible prose and informative, inviting style informs the reader without sounding like a textbook or a polemic.

The book defines rarity in terms of population density, range size, and habitat specialization. It then goes on to consider the causes of rarity, both natural and human induced, by asking questions such as: Has the species been rare throughout its evolutionary history? Or is rarity a recent phenomenon triggered by stressors such as habitat loss or poaching? It turns out that certain geologic and geographic factors can drive the process of speciation and create hotbeds of biodiversity and rarity within definable boundaries, even with no human presence on the landscape. There is also the idea of where a species fits into the food chain, with large carnivores necessarily existing at low densities on the landscape as a result of the laws of thermodynamics. Through Dinerstein’s observations, the reader becomes aware that the answer to the question of whether or not a species has always been rare is important in answering other questions related to ensuring its continued survival.

Eric Dinerstein, Author, Naturalist, and Senior Scientist, WWF

Eric Dinerstein, Author, Naturalist, and Senior Scientist, WWF

Dinerstein admits early on to the book’s bias towards mammals, birds, and vascular plants. It is likely that these taxa, with their widespread “charismatic” appeal, will create increased interest in the book for a broad audience, from a high-school student with an interest in animals or science, to an elected official with a role in international policy making, to a farmer wanting to better understand how agricultural practices impact the landscape. Each chapter is brimming with stories of exotic animals and plants. There are giant anteaters, one-horned rhinos, black-necked cranes, leopards, tree kangaroos, Berlepsch’s six-wired birds of paradise, and saola, just to name a few. The lack of photos had me wishing for my childhood collection of Safari Cards, but there are about a dozen illustrations sprinkled throughout the text, and maps to help zero in on the more exotic locales. You could fill your reading list for the next year just from the fascinating selections included in the book’s annotated bibliography, and the handy subject index makes it easy to retrieve that one idea or species you are trying to remember. Parts of this book are difficult to read: details of the many bird species already lost from Hawaii, and the pressures faced by the remaining honeycreepers; the lasting psychological effect of human conflict on indigenous animals; the cycle of commodity farming on increasingly depleted soils. But it’s not all doom and gloom.

There are memorable anecdotes about the field biologists trying to answer the big questions. There is Carly Vine, and her Labrador retriever, Mason, a rescued dog who is helping to increase our understanding of large mammal density in the Brazilian Cerrado. And there’s Sarah Rockwell, who learned to hide behind jack pines and crawl through the woods on her belly to observe nesting behavior of Kirtland’s warblers, eventually to be rewarded with the ability to locate their nests. All of this work is leading to important observations about how these animals react to changes on the landscape, and how we might be able to be manage it in a way which provides a future for its imperiled residents.

An issue which raises an alarm from the author is the globally increasing trend in the rate of population loss, or “population rarity.” As species loose individual populations, the remaining individuals become more susceptible to extinction. This leads to an emphasis on the idea of “conservation landscapes,” or connecting patches of habitat, within an altered matrix, as a tool for increasing the resiliency of the diversity which remains. Dinerstein also reminds us that it is unwise to consider a species at too much of a local scale, and warns against considering a species to be “common”, when in fact it may simply be “obvious” within a limited range.

As Dinerstein points out, we Rhode Islanders live in a landscape that has already suffered a “trophic cascade.” This phenomenon occurs through the loss of one or more keystone species, in our case the top predators – puma and wolves. When this happens, it affects those species below, and even has impact on other things, like soil quality. Here in New England, this effect, coupled with habitat fragmentation, has led to the current overpopulation of white tailed deer. Not only does this create a nuisance to humans, through increased vehicle collisions and Lyme disease, it also impacts other species, such as woodland songbirds, through over browsing and the resulting exposure of nests and young to predation. Rhode Island is a state that is home to only a handful of species which are currently listed as Threatened or Endangered under the U.S. Endangered Species Act. Why then is it important for Rhode Islanders to be concerned with the fate of rare species?

An important point that the book makes is that some of the animals that are considered rare today, were once considered common. Habitats that currently occupy large swaths of the landscape may become scarce if, for instance, rising sea levels begin to squeeze out salt marshes as they bump up against urban sprawl. Do we have a good understanding of how much the amount of habitat fragmentation will affect “how much is enough” for our own suite of biodiversity? What emerging technologies may allow us to gather more information, more accurately, and increase our knowledge? Dinerstein gives us the example of TrackTags, which have been used to gather continuous location data on collared jaguars. When mapped against a sparser data set of locations gathered from VHF radio collars, on the same cats over the same time period, the new technology allows for a much more robust understanding of how the animals utilize their home ranges.

The Rhode Island Ecological Communities Classification (RIECC) (see note below) has identified almost 100 ecological Community Types in Rhode Island. How much do we really know about the more than 150 animals and 400 vascular plants considered to be of high concern for conservation in our State? By increasing our understanding of the relationships between these species and their habitats, and how these communities are likely to be affected by things like urbanization and climate change, we can begin to plan for ways to conserve our state’s biodiversity now, and in the future. And, if we can’t predict which common animals of today will become the rare species of the future, then we will have the ability to conserve important habitats – biodiversity source areas – at scales which are likely to support populations of a wide variety of native species, and to ensure that there are corridors to connect these refuges for the species that require more room to roam.

The Kingdom of Rarities leaves us in Bhutan, a country high in the Himalayan mountains, which has committed to conserving an astounding 60% of its land area under native forest cover. From this vantage point Eric Dinerstein poses the idea that, in order to find lasting solutions to conserving our biodiversity, we will need to find a way to mainstream conservation into our cultural, economic, and even religious norms, by linking a science-based approach that focuses on populations, with a philosophy that gives ethical value to individual species and their well-being. A lofty goal perhaps, but one that is being achieved in a country, traditionally perceived as poor by the outside world, where they measure their conservation achievements not in terms of economics, but in terms of “gross national happiness.”

RIECC NOTE:
The Rhode Island Ecological Communities Classification (RIECC) has been prepared, with RINHS as the lead contractor, to support development of a detailed ecological communities map and database to serve multiple conservation needs in Rhode Island including, but not limited to, the State Forest Assessment and State Wildlife Action Plan. The classification is a predecessor of a project to acquire…data for the state of Rhode Island and produce a digital ecological communities GIS database. When complete, the digital ecological communities GIS database will serve the entire conservation community, resource managers, and cities and towns in the state.

Although the entire Rhode Island landscape has been altered by anthropogenic processes to varying degrees, a particular feature of natural communities is a lack of naturalized, non-native plants. In fact, the best examples of most natural communities contain only native species. For land managers the appearance of an exotic species in a natural community, especially those known to be invasive, can serve as an early warning of potential threats to that community’s ecological integrity. In contrast, a high percentage of introduced, invasive species in a habitat is indicative of a degraded natural community, and perhaps one that may never be restored.

RINHS was the prime contractor on the RIECC. The printed guide is available as a PDF. RIECC PDF:195K

Posted in Animals, Biodiversity, Conservation, Ecological Communities, News |