The American pygmy shrew (Sorex hoyi), also called the eastern pygmy shrew, is a small shrew found throughout much of Alaska, Canada, and the northern contiguous United States, as well as south along the Appalachian Mountains and in a small region in the Colorado and Wyoming Rockies. The species was first discovered in 1831 by naturalist William Cane in Georgian Bay, Parry Sound.
This animal is found in northern coniferous and deciduous forests of North America. It is believed to be the second-smallest mammal in the world, but has an extremely large appetite for its size. Due to its fast metabolism, it needs to eat constantly. It digs through moist soils and decaying leaf litter for food.
Description
The American pygmy shrew is the smallest mammal native to North America and is one of the smallest mammals in the world, just slightly larger than the Etruscan shrew of Eurasia. Its body is about long including a 2-cm-long tail, and it weighs about . Its pelage is generally a reddish or grayish brown during the summer, and a white-gray color during the winter. The underside is generally a lighter gray. This animal molts about twice a year, once during late summer, and again during the spring. It has a narrow head with a pointed nose, and whiskers. The eyes are small and well hidden. The primary senses used for hunting are hearing and smell.
Phylogeny
Sorex hoyi was originally placed in the genus Microsorex, which was a subgenus under Sorex until more research had been done. The American pygmy shrew is in the order Soricomorpha and the family Soricidae. Its two closest relatives are the smokey shrew (S. fumeus) and the large-toothed shrew (S. macrodon). This genus is believed to have appeared in the late Miocene.
Distribution and habitat
Pygmy shrews are distributed throughout the subalpine and boreal areas of North America, ranging from Canada and Alaska Its diet is almost exclusively protein-based. To stay alive, the pygmy shrew has to eat three times its body weight daily, which means capturing prey every 15 to 30 minutes, day and night; a full hour without food means certain death. Because of this high metabolism, the pygmy shrew never sleeps more than a few minutes at a time, as it is in a constant search for food. The gestation period is estimated to last about 18 days.