Mammals

MAMMALS (MAMMALIA)

The first mammal-like reptiles appear in the fossil record about 290 million years ago, but it seems to have taken about another 85 million years for the first true mammal species to evolve. Mammals were marginal species in the wildlife of the planet from about 200 million years ago until around 65 million years ago because the world was dominated by the dinosaurs during this period. After the virtual “nuclear winter” caused by the huge meteor that fell in Yucatan about 65 million years ago, the dinosaurs became extinct and the mammals began their period of dominance, which continues today. The first horses appeared about 55 million years ago, the first whales about 35 million years ago, and the first apes about 24 million years ago.

As described in the chapter on Geological History, the first recorded mammals that occurred at what is now Martha’s Vineyard were here about five million years ago. The chapter on Fossil Record lists several including whales, a rhinoceros, a mastodon and probably seals or walrus (Oldale, 1992:29-30).

By Pleistocene time during and near the end of the Wisconsinan glacial period when the ice sheet had retreated to Canada, much of the continental shelf was still above sea level. The exposed shelf was populated by wildlife that still occurs in habitat comparable to what existed then but which is found today only far to the north. There is no surviving evidence that any of these mammals occurred 10,000 to 12,000 years ago exactly where Martha’s Vineyard is today, but it is probable that many of them did. Species typical of the area at that time probably included Wooly Mammoth (Mammuthus primigenius) and Mastodon (Mammut americanum) [see Whitmore et al. 1967], Muskox (Ovibos moschatus), Arctic Hare (Lepus arcticus), Arctic Fox (Alopex lagopus), and Barren Ground Caribou (Rangifer arcticus), Polar Bear (Thalarctos maritimus), Walrus (Odobenus rosmarus), and Ringed Seal (Phoca hispida) certainly were found regularly in the near-shore ocean, and possibly Beluga Whale (Delphinapterus leucas).

A little later, the entire suite of species now found only in the boreal forest probably lived here, including Mountain Lion (Felis concolor), American Elk (Cervus elaphus), Woodland Caribou (Rangifer caribou), Grizzly Bear (Ursus horribilis), Gray Wolf (Canis lupus), Lynx (Lynx Canadensis), Fisher (Martes pennanti), Pine Marten (Martes Americana), Moose (Alces Americana), Snowshoe Hare (Lepus americanus) and Wolverine (Gulo gulo). Several of these probably patrolled the shores of the rivers which flowed out from the base of the ice.

Later still, after the rising of the sea created the Vineyard about 5,000-6,000 years ago, when a moist forest primarily of spruce, hemlock, balsam fir, willow, pine, black birch etc. clothed the island (Ogden, 1958, 1961), the following species very likely still lived here: Northern Flying Squirrel (Glaucomys sabrinus), Porcupine (Erethizon dorsatum), Short-tailed Weasel (Mustela erminea), Long-tailed Weasel (M. frenata), Smoky Shrew (Sorex fumeus), Red-backed Vole (Clethrionomys gapperi), and Northern Bog Lemming (Synaptomys borealis). To date, no concrete evidence of their presence here has been discovered, although all but the Lemming still live in nearby eastern Massachusetts today. It seems most likely that either natural alteration of the island’s environment during the last 1,000 years or so, extermination by the indigenous people, or the wholesale deforestation which occurred after settlement by Europeans eliminated the habitats on which they depended.

In contrast to those probable resident species for which there is no concrete evidence, several species are known from kitchen middens that are no longer present (Byers and Johnson, 1940; Huntington, 1962; Waters, 1967a; Keith, 1969; Perlman, 1977; Largy and Burns, 2001): Red Squirrel (Tamiasciurus hudsonicus), Gray Fox (Urocyon cinereoargenteus), Beaver (Castor canadensis), Bobcat (Felis rufa), Indian Dog (Canis familiaris), Mink (Mustela vison), and Black Bear (Ursus americanus). Walrus skulls have been brought up in fishermen’s nets from Vineyard waters (Lyell,1845). The form known as the Sea Mink (Mustela vison macrodon) almost certainly occurred in the waters around the island although no specific remains have been found to date.
As for the whales and porpoises in the following list, it should be mentioned that several other species may be discovered in island waters in future. As is obvious, observations of living animals are much more difficult to obtain, so many records pertain to dead specimens washed up on beaches, and precise status and numbers are uncertain. One thing is certain: the whale and porpoise populations here were dramatically more numerous 200-250 years ago before the virtual wholesale slaughter of these animals by the pelagic whaling industry, such that their numbers have been reduced by at least 90%. The entire Atlantic Gray Whale (Rhachianectes glaucus) population was driven to extinction. There is no longer any excuse for any more whaling anywhere by anybody!

Over the years, a number of species of mammals have been introduced, at least one inadvertently and others intentionally. The consequences of most introductions have been unfavorable, as is usually the case. Fallow Deer (Platyceros dama) were introduced from zoo stock in the 1932-1938 period and increased to about 150 by 1962 (Keith, 1969:90) but has since declined and may no longer be present. The relict population of New England Cottontails (Sylvilagus transitionalis) which was marooned here when the sea rose apparently died out when Eastern Cottontails (S. floridanus) carrying a disease were introduced in the 1920’s. The native populations of Striped Skunk (Mephitis mephitis) and North American Raccoon (Procyon lotor) were exterminated by island residents as pests in the 1890-1910 period, only to be translocated (with significant impact on the ecology of the island) about 1960. The native Red Fox (Vulpes vulpes) population was also exterminated by about 1825, translocated in 1877-1894 and re-exterminated by 1905 since it had become a pest again (see Waters, 1963b, 1967b). Eastern Chipmunk (Tamias striatus), a ferocious nest predator on ground-nesting birds, which had never been present before, was also introduced about 1960. Norway Rat (Rattus norvegicus) was one of the first introductions, probably from ships as early as colonial times. Feral Cats (Felis catus) destroy more wildlife on this island than any other type of creature; the species originally came with the first colonists. Three species of large rabbits were released in the 1910-1926 period as game animals but all shortly died out: European Hare (Lepus europaeus), Snowshoe Hare (L. americanus) and Black-tailed Jackrabbit (L. californicus). One of these, probably the European Hare, became common on Nomans Land Island for a while and was hunted there, but the precise species is no longer known.

There are several mysteries concerning mammal species on the island. The type specimen of Hairy-tailed Mole (Parascalops breweri) was apparently collected on the island about 1840 (Bachman, 1842) but has not been recorded since. This species inhabits woods and meadows with loose sandy well-drained soil; there would seem to have been ample habitat for it here since its discovery so why it would disappear is a puzzle. Perhaps closer searching in the future will discover it again. Surprisingly, no certain records exist for either House Mouse (Mus musculus) or Black Rat (Rattus rattus), both species that arrived from Europe in most of New England by late Colonial times. Reports of possible living Gray Fox (Urocyon cinereoargentatus) sightings in the 1970s and 1980s have not been confirmed. After years of dubious reports of living Coyote (Canis latrans) on the Vineyard, along with the unambiguous presence of at least one dead one washed up on a beach (2004), the first living individual was confirmed present on a trail camera on the North Shore in 2010. The Elizabeth Islands, where the species is common, is a plausible point of origin for Coyote arriving naturally on the Vineyard; it is not that long a swim for a desperate or determined canid. Sight reports of the individual(s) continue, with the most recent on a trail camera in 2021. Earlier published reports of Virginia Opossum (Didelphis virginiana) and of Woodland Jumping Mouse (Napaeozapus insignis) have proved, on further research, to be in error.

The zoogeographical affinities of the original native land mammal population was clearly northern due to northern forms being left behind (New England Cottontail, Mink, Beaver, Red Squirrel) when the sea rose creating the island. Introductions of more southern forms (Eastern Chipmunk, Eastern Cottontail) have biased the composition of the current resident land mammal fauna slightly southward.

There are several concerns about the current status of some mammals on the island. For one, the White-tail Deer (Odocoileus virginianus) population has increased sharply with the growth of more mature forest and is now thought to number over 3,000 animals. As the human population increases and more land is posted, these deer do an increasing amount of damage to both ornamental shrubbery and the native habitat in winter, especially in years when there are few acorns; this will eventually affect the health of the deer herd and damage the forest habitat itself from overgrazing unless control measures are undertaken. See McShea et al. (1997) and especially Wilson and Childs (1997) within that volume for a detailed discussion of the impact of excessively large deer herds and their role in spreading diseases such as Lyme, ehrlichiosis, and babesiosis. The island population of Striped Skunks (Mephitis mephitis) has risen since their translocation, and the highest densities occur near towns where human food subsidies are most abundant. A density estimate in Aquinnah fell within the range of other highly subsidized populations in campgrounds or campuses on the mainland (Johnson 2016). It has become a pest and a significant egg predator, along with the Raccoon (Procyon lotor), of many species of ground-nesting birds, snakes, and turtles. However, both predator populations can decline significantly from periodic distemper outbreaks. Johnson documented 50 – 60 % mortality in skunks in her study in 2005 (Johnson 2016).

In the checklist, current residents are indicated by “R”, extirpated former residents by “FR”, species with an endemic race by “ER”, introduced species by “I”, and oceanic species by “O”. A brief description of status is also given. Clearly, “common” is a term relative to the species involved and means a different thing for a squirrel than it does for a whale.

Allan Keith; edited by Luanne Johnson, July 28, 2022