Current Research
Small rodents in mosaics of restored and remnant prairies
Restoring and reconstructing prairies has become increasingly popular and currently a mosaic of small remnant and large restored prairie patches now coexist around Northfield, Minnesota. For the past several years we have been studying the effects of this changing landscape on small prairie rodents. In particular, we considered whether prairie rodents found on remnants had colonized restored prairies, but also whether the species composition in restored versus remnant prairies and on the distribution of prairie voles (Microtus ochrogaster), a species of “special concern” in Minnesota. Rodents were trapped in 10 prairies of various sizes in southern Minnesota over three summers. Each of the four species we focused on was found in a subset of restored prairies, indicating dispersal is occurring. While meadow voles (Microtus pennsylvanicus) were disproportionately found in restored prairies, prairie deer mice (Peromyscus maniculatus bairdii) were more often found in remnant prairies. Moderately high numbers of western harvest mice (Reithrodontomys megalotis) were found in the area, suggesting that the range and abundance of this species has increased. Although once common in Minnesota, prairie voles were found in small numbers. These results show that the elimination and reconstruction of Minnesota’s prairies has changed small rodent communities in this part of the state. Differences in species composition between remnant and restored prairies emphasize the importance of conserving the small number of remnants that remain.
Previous Research
Many animals store or cache food for future use. Different species cache food in different ways. Grey squirrels (Sciurus carolinensus) scatter hoard food items, typically burying items individually throughout their territory. Most research on red squirrels (Tamiasciurus hudsonicus) suggest they are what we call larder hoarders, collecting many cones and carrying each cone back to a single central cache or “larder hoard”. Many different hypotheses have been proposed to explain why gray squirrels scatter hoard and red squirrels larder hoard. I found populations of red squirrels in the southern Adirondacks of New York State that use both caching patterns. I used this intraspecific variation in caching behavior to test several hypotheses. I marked cones on their tips with metal tags, set them out on large grids and then relocated them with a metal detector after they had been cached by squirrels. I found that the caching strategy red squirrels use depends on the size of the cone. Big cones were carried farther and brought all the way back to the larder hoard, while small cones were carried just a few meters and cached in many separate locations.
I applied this cone marking and tracking technique to an endangered subspecies of squirrel. The Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is one of 25 subspecies of red squirrels found throughout North America. The Mt. Graham subspecies, which is found only on the Pinaleno Mountains of Southeastern Arizona, was added to the Federal Endangered Species List in 1987, when the estimated population of the species was fewer than 400. The Mt. Graham subspecies has been isolated from other subspecies since the end of the Pleistocene glacial period. Trapping and marking of squirrels was banned when several individuals died while being handled.
Mt. Graham, sometimes called a “sky island” is attractive to astronomers because of its high altitude (10,799 ft) and dry, clear air. Construction began in about 1989 on a trio of telescopes sponsored by the University of Arizona and the Vatican among others. Telescopes and new roads to the top of the mountain were built while “Earth Firsters” (a somewhat radical environmental group) plotted road blocks, organized tree sitters and placed nails in trees. I monitored red squirrel foraging behavior in several different habitats on the mountain.
