The VT Small Mammal Atlas has moved and is now maintained by our friends at the Vermont Center for EcoStudies’ Vermont Atlas of Life. Check it out!
The Vermont Small Mammal Atlas was completed from 2008 to 2011, with the goal of learning more about the distribution and habitat requirements of 23 species of terrestrial small mammals in Vermont.
The project was carried out by the University of Vermont and the NorthWoods Stewardship Center, and pooled data from field surveys conducted at 47 sites across the state from 2008 to 2010, incidental small mammal data collected in 1998 during herptile surveys, records from UVM’s Zadock Thomson Natural History Collection and several other museums, and a literature review (including some unpublished sources).
The field survey portions of the dataset contributed over 3,000 records from a total of 17,166 trap nights of effort (total nights trapped x number of traps used). These captures represented a total of 20 species, five of these rare. Among the rare species, these surveys documented 19 previously unknown populations and confirmed the continued presence of two historical populations.
The project was funded primarily by a State Wildlife Grant (Vermont Department of Fish and Wildlife), with additional support through a Vermont Department of Forest, Parks, and Recreation contract and volunteers.
VT Small Mammals: Who are they?
Small mammals are defined as all mammal species weighing less than 500 grams (1.1 lbs, or slightly more than 4 sticks of butter) as adults.
Although Vermont’s nine species of bats also fall within this category, we have not included bats in this website. For information about bats, visit VT Fish & Wildlife Department: Got Bats?
Of 58 species of mammals currently found in Vermont, 35 are small mammals. These vary widely in preferred food, habits, habitat use and lifestyle and fall within seven taxonomic families. Vermont’s small mammal diversity includes 9 bat species; 6 shrews; 5 squirrels; 4 voles; 3 mice; 2 each of moles, weasels, rats, and jumping mice; and 1 bog lemming.
Visit VT Fish & Wildlife for further explanations of species state rankings.
VT Small Mammals: Why do they matter?
Too often small mammals only seem important when they are causing us harm. It is true that some species, because their feeding or habitat preferences conflict with ours, can do substantial damage.
Examples include:
Pine Vole – feeds on roots of apple trees, affecting orchards in sandy soils
Meadow Vole – girdles the bases of ornamental or apple trees
House Mouse – nests in houses and consumes human and livestock food
Hairy-tailed mole – creates tunnels and dirt piles in lawns, etc…
As with most wildlife species, vilifying small mammals ignores their important role in our ecosystems and their fascinating and unique life histories and adaptations. For instance, our VT small mammals include a species that weighs less than a dime, another that runs on water, and another that is among the world’s only venomous mammals!
Small mammals are incredibly good at reproducing and commonly give birth to 50+ young per year. Meadow voles are among the most fecund and are potentially capable of producing 17 litters or 187 offspring over 1 year, and over 500 during a maximum lifetime of 2.7 years.
So why aren’t we overrun with these rodents? Because they are a food source for most of the carnivores and omnivores living in our fields and forests. Without this food base our wildlife pyramid might collapse. Small mammals also serve many other ecological services, including seed and fungal spore dispersal, soil aeration, constructing tunnels used by other wildlife, and controlling invertebrate populations.
Small mammals also account for much of our mammal diversity and biomass, yet we have much to learn about them. Of Vermont’s 35 small mammal species, 13 (37%) are considered of highest conservation priority by the Vermont Comprehensive Wildlife Conservation Strategy (CWCS 2005), mainly because of a lack of understanding about their distribution and population trends.
VT Small Mammals: What can I do?
Small Mammal Atlas: Methods
Small mammals were trapped using Sherman live traps, Museum Special snap traps and pit traps. Snap and pit traps were included to better sample shrews of the genus Sorex, which are often undersampled by other trapping methods, and for locations (like rock outcrop crevices) that can only be effectively sampled with snap traps. Live traps were baited each day with rolled oats and snap traps were baited with peanut butter. Traps were checked early the following morning and the animals captured were identified to species when possible. Animals captured alive that could be identified to species were marked with an ear punch and released at the site of capture. Voucher specimens of representatives of each species captured were prepared and are housed in the Zadock Thompson Natural History Collections of the University of Vermont. Collecting protocols followed the standard methods recommended for small mammals (Wilson et al. 1996; Animal Care and Use Committee 1998). Difficult to identify species were verified using DNA analysis or through examination of skulls (in the case of voucher specimens). Pit traps were not used at survey sites on most state lands, due to permitting limitations.
Each site was surveyed with a minimum of 100 traps for 3 nights for a total of approximately 300 trap nights. Specimens were also salvaged from small mammals captured during herp (amphibian and reptile) survey that employed pit traps and drift fences. These specimens had been frozen in bags with capture locality descriptions. After the specimens were thawed they were identified to genera or species when possible, the sex determined, four basic body measurements taken, and the skull removed and tagged to allow further verification of species identity. Skulls were and continue to be processed using a dermestid beetle colony to remove the flesh.
Once cleaned the skulls are stored in vials and examined under magnification to verify species identity. Specimens were also obtained from several additional sites between 2008 and 2010 from incidental collections by the authors and from specimens provided to the lead author by other biologists. New records were obtained for all counties in Vermont with the exception of Grand Isle.