Carmen M. Salsbury

SEASONAL BODY TEMPERATURE FLUCTUATIONS AND ENERGETIC STRATEGIES IN FREE-RANGING EASTERN WOODCHUCKS (MARMOTA MONAX)

Abstract During a 2-year period, radiotelemetry was used to continuously monitor body temperature (Tb) of free-ranging woodchucks (Marmota monax) in southeastern Pennsylvania. Hibernation was preceded by daily Tb fluctuations (“test drops”) of 2–4°C. During hibernation, woodchucks exhibited the characteristic pattern of torpor bouts. Time of arousals occurred randomly, but onset of torpor occurred predominantly between 1800 and 0000 h. Males had shorter hibernation periods (mean of 104.8 days) than did females (121.8 days). Males had shorter torpor bouts, but euthermic bouts were the same length as in females. Males also maintained higher Tb during torpor. Overall, the cost of hibernation was greater for males than for females: males spent 38% more energy than did females. The primary energetic expense for both sexes was the periodic maintenance of euthermy throughout hibernation, which accounted for 75.2% of the energy budget for males and 66.8% for females. Compared with the 1999–2000 hibernation seasons, woodchucks during the 1998–1999 season had longer euthermic bouts, fewer torpor bouts (11.8 compared with 13.1), and spent less time in torpor (68% compared with 75%). These differences conserved more energy during the 1999–2000 hibernation season and may have been the result of severe drought conditions during summer 1999. After emergence from hibernation, woodchucks generally maintained a constant state of euthermy throughout the active season, with Tb fluctuating daily by 1–2°C. However, during the summer drought of 1999, daily Tb fluctuated 8–17°C in 5 of 8 woodchucks, presumably to conserve energy and water.

Movement and habitat use of two aquatic turtles (Graptemys geographica and Trachemys scripta) in an urban landscape

Our study focuses on the spatial ecology and seasonal habitat use of two aquatic turtles in order to understand the manner in which upland habitat use by humans shapes the aquatic activity, movement, and habitat selection of these species in an urban setting. We used radiotelemetry to follow 15 female Graptemys geographica (common map turtle) and each of ten male and female Trachemys scripta (red-eared slider) living in a man-made canal within a highly urbanized region of Indianapolis, IN, USA. During the active season (between May and September) of 2002, we located 33 of the 35 individuals a total of 934 times and determined the total range of activity, mean movement, and daily movement for each individuals. We also analyzed turtle locations relative to the upland habitat types (commercial, residential, river, road, woodlot, and open) surrounding the canal and determined that the turtles spent a disproportionate amount of time in woodland and commercial habitats and avoided the road-associated portions of the canal. We also located 21 of the turtles during hibernation (February 2003), and determined that an even greater proportion of individuals hibernated in woodland-bordered portions of the canal. Our results clearly indicate that turtle habitat selection is influenced by human activities; sound conservation and management of turtle populations in urban habitats will require the incorporation of spatial ecology and habitat use data.

The Distribution of Fox Squirrel (Sciurus niger) Leaf Nests within Forest Fragments in Central Indiana

Abstract We examined the abundance and placement of leaf nests by fox squirrels in six urban woodlots in central Indiana ranging in size from 1.06 to 8.28 ha. Four of the woodlots were disturbed, or subject to extensive human impact, whereas the remaining two were nature preserves. We counted all leaf nests present in each woodlot and recorded nest tree characteristics. We then conducted a quantitative vegetation analysis of trees present and estimated percentages of herbaceous and shrub cover along a minimum of two 100 m transects at each site. Fox squirrels showed a preference to build nests in certain species of trees. However, preference for nest tree species was not consistent across sites. Fox squirrels preferred to build nests in large trees with vines in the canopy at all sites. Characteristics of nests and nest trees did not differ among sites, but nest density was greater in the disturbed sites compared to the nature preserve sites. The nature preserve sites differed from the disturbed sites only with regard to the amount of shrub and herbaceous cover; shrub cover was greater and herbaceous cover was less at the disturbed sites. Results of this study suggest that fox squirrels are flexible with regard to nest tree species used and that the choice of a nest tree is dependent, in part, on tree size and the presence of vines. Further, a higher density of leaf nests in disturbed woodlots suggests that habitat disturbance and fragmentation due to urbanization may not have detrimental effects on the abundance and persistence of fox squirrels.

Energetics of Hibernation in Woodchucks (Marmota monax)

Woodchucks hibernate singly with a daily mass loss of 5.2 7g and a specific mass loss (DML) of 1.94. Woodchucks have a higher metabolism than yellow-bellied marmots, who also hibernate singly. Woodchucks allocate a greater percentage of time and energy to euthermy, spend less time torpid and save less energy during hibernation than do yellow-bellied marmots, and save about the same amount of energy as alpine marmots. Woodchucks rely on a combination of large body size and a short hibernation period as the major hibernation strategy whereas the yellow-bellied marmot is energetically more efficient and the alpine marmot utilizes social thermoregulation.

The effect of molt on oxygen consumption of yellow-bellied marmots (Marmota flaviventris)

Abstract 1. 1. Mean specific VO2 of five adult female yellow-bellied marmots was significantly lower in postmolt individuals than in premolt animals. 2. 2. Mean body temperature did not differ significantly between premolt and postmolt marmots. 3. Conductance was significantly lower in postmolt than in premolt marmots. 3. 4. Because body mass was significantly larger and total VO2 significantly lower in postmolt than in premolt, the decrease in specific VO2 is attributed to decreased conductance and not to the accumulation of metabolically inactive tissues.

Distribution Patterns of Sciurus niger (Eastern Fox Squirrel) Leaf Nests Within Woodlots Across a Suburban/Urban Landscape

Abstract To determine habitat characteristics that influence Sciurus niger (Eastern Fox Squirrel) abundance and distribution within a suburban/urban landscape in the midwestern United States, I documented the density and placement of fox squirrel leaf nests in 20 woodlots in the Indianapolis metropolitan area, Marion County, IN. The woodlots varied in size (0.94 to 19.5 ha), approximate age, shape, and degree of isolation from other woodlots and suitable squirrel habitat in the surrounding area. Only 8.0% of nests were located in a tree with another nest, and nests were randomly distributed in all but one woodlot, where they were uniformly dispersed. Nest density was not significantly related to woodlot size, approximate age, shape, or degree of isolation. Fox squirrel leaf nests were not found in greater densities along the edge of each woodlot, contrary to previous reports. My results suggest that the distribution patterns of fox squirrels within suburban/urban landscapes are similar to patterns within landscapes fragmented by agriculture.