This project was funded through a co-operative agreement between the Alaska Center for Conservation Science – Zoology Program and The Alaska Department of Fish and Game – Threatened, Endangered and Diversity Program
The state of Alaska’s Wildlife Action Plan (2006) highlighted the need to collect and archive material to examine taxonomic distinctiveness and to map the spatial distribution of taxa to examine habitat use by insular endemic small mammals in southwestern Alaska and the Bering Sea region. In 2012, the zoology program conducted small mammal surveys on St. Lawrence Island with the objective of taking an inventory of current small mammal taxa inhabiting the island, determining species distributions in representative habitats, describe habitat use for each species, and collect vouchered specimens to be housed at the University of Alaska Museum of the North in Fairbanks, Alaska.
St. Lawrence Island was connected intermittently to mainland Alaska and Russia by the Bering Land Bridge. The Bering Land Bridge allowed interchange of fauna between Asia and North America and served as a refugium for taxa from advancing ice sheets. As a result of being connected and subsequently isolated from neighboring continents over time, a unique set of small mammal taxa evolved on the island. Small mammals endemic to the island include the St. Lawrence Island shrew (Sorex jacksoni), and subspecies of the northern red-backed vole (Myodes rutilus albiventer), root vole (Microtis oeconomus innuitus), Nearctic collared lemming (Dicrostonyx groenlandicus exsul), and arctic ground squirrel (Spermophilus parryii lyratus). With the exception of Sorex jacksoni, the mammals occurring on St. Lawrence Island represent species which are widely distributed in boreal regions. However, they have often been regarded as being distinct from closely related forms occurring on adjacent continents.
We captured 61 individuals from the 19th to the 27th of July, 2012, using Sherman and pitfall traps placed in all major habitat types near the villages of Gambell and Savoonga. We compared our trapping results to earlier studies to determine the current status, distribution, and relative abundance of each taxa in relation to previous years. In 2012, we found that root and northern red-backed voles were most abundant, occurring in mesic and mesic to dry dwarf shrub and herbaceous habitats, respectively. Arctic ground squirrels were observed in mesic to dry habitats, particularly in areas with sandy soil or rocky outcrops. The St. Lawrence Island shrew was the least abundant of the species we captured (n= 2), and was found exclusively in the rocky auklet colonies near Savoonga. Despite targeting trapping effort in habitats where Nearctic collared lemmings were thought to occur, we were unable to capture or observe lemmings in any habitat. Although this survey was limited to a relatively short time period, its findings suggest the need for additional surveys to determine the status of the Nearctic collared lemming and to determine factors that regulate the population size of each small mammal species on the island.
Funding was provided by the University of Alaska Anchorage and the Alaska Department of Fish and Game Wildlife Diversity Program. Specimens were collected under Alaska State Permit 12-140 and IACUC approval was received under permit number 342177-2. We thank Dr. L. Olson for trapping guidance and loaning Sherman traps. We thank C. Booshu, C. Roonooka, and the Gambell and Savoonga IRA councils for assistance with obtaining trapping permissions and land crossing permits. We thank W. Walunga, J. Walunga, M. Walunga, and E. Noongwook for providing transportation and guiding services. Permission was granted by Sivuqaq Inc. to trap on St. Lawrence Island.