Observations on Lemmings from Barter Island, Alaska

Although lemmings are the most abundant and perhaps the most characteristic of Arctic mammals, there is little published information on details of their life history. Degerb0l and M0hl-Hansen (1943) describe reproduction and moult in captive Dicrostonyx from Greenland, Sutton and Hamilton (1932) and Shelford (1943) give information on the numbers and appearance of lemmings in the Hudson Bay region, and Rausch (1950) discusses the ecology and abundance of lemmings (chiefly Lemmus) in the vicinity of Barrow, Alaska. Included here are some further observations on the midsummer habitat of the lemmings on the Arctic slope, and data on the growth of young collared lemmings (Dirostonyx rubricatus rubricatus) in captivity. Observations in the field were made along the Arctic Ocean at Barter Island, Alaska (lat. 70?, long. 144?), and the adjacent mainland from August 9 to 14, 1950. Subsequent studies on the animals in captivity were made at Fairbanks, Alaska (August 15 to September 5) and at Madison, Wisconsin (September 6 to January 6). These observations were made incidental to a study of temperature regulation in mammals supported in part by contract with the Air Materiel Command, U. S. Air Force, and research grant from the Wisconsin Alumni Research Foundation. We are particularly indebted to the Arctic Aeromedical Laboratory, Ladd Air Force Base, for its facilities and assistance which were extended through Col. J. Bollerud. The identification of the specimens is through the kindness of Dr. H. W. Setzer and Dr. D. H. Johnson of the U. S. National Museum. The tundra at and near Barter Island is superficially quite flat although in many areas there are numerous depressions and ridges one to four feet in height, attributed to freezing and heaving of the ground. The ground cover at this time was a mat of grasses and sedges, with numerous small wild flowers and occasionally scrub willow from several inches to a foot high. There was an abundance of tunnels and open runways along these ridges and out onto the adjacent flat areas. Although droppings were common and appeared fairly fresh, evidently due to the preserving action of the cold wet weather, the lemmings themselves were very scarce, as was also noted in the Point Barrow region during the summer of 1950 by Daniel Q. Thompson. Over a four-day period of intensive search, 30 "Sherman" live traps with solid or mesh top and sides were kept set and baited and several hundred tunnels were dug up. Only two brown lemmings (Lemmus trimucronatus alascensis) and three collared lemmings (Dicrostonyx r. rubricatus, one with young) were taken. Of these animals, three were captured by hand after observation, two were dug out of tunnels (one with young), and one was taken in a trap. Once an active runway had been discovered, the darker and moister fresh droppings could readily be distinguished from very common old droppings. Most of the tunnels were quite short, averaging about a foot in length. The ground was nearly saturated and the tunnels, usually only two or three inches from the surface, were cold and damp. There would commonly be an open runway through the grass, and every four or five feet a short tunnel with a single opening. Appar180 Vol. S3, No. 2