Geology topics

J.K. Vreeland

Publications and source records attributed to J.K. Vreeland.

3 recordsLinked to original sources

USGS2016

Evidence for range contraction of snowshoe hare in Pennsylvania

In Pennsylvania, Lepus americanus (Snowshoe Hare) is near the southern limits of its range and at risk of range contraction because of loss of early-successional forest and impacts of climate change. We used hunter-harvest data to investigate changes in the distribution of Snowshoe Hare in Pennsylvania (1983–2011), forest inventory and land-use data to assess changes in amount and distribution of early-successional forest (1988–2011), and occupancy modeling (2004) to identify habitat and climate variables that explain the current distribution of Snowshoe Hare. We determined presence of Snowshoe Hare based on visual sightings, observations of tracks, and DNA analysis of fecal pellets, and used repeated visits to sampling sites and occupancy models to estimate occupancy rates (Ψ). Hunter-harvest data indicated the range of Snowshoe Hare in Pennsylvania contracted towards northwestern and northeastern portions of the state. Based on occupancy modeling, Snowshoe Hare were most likely to occupy early-successional and mixed deciduous-coniferous forest types and areas with colder winter temperatures, which coincided with the distribution of hunter harvests. Among the 4 forest types, we estimated Ψ = 0.52-0.79 and Ψ = 0.10-0.32 where winter temperatures were coldest and warmest, respectively. Total forest loss was <1% during 1988-2011, and the loss of early-successional forest in the current and former range of Snowshoe Hares was similar as were mean patch size and a fragmentation metric of early-successional habitat. Thus, changes in forest characteristics did not explain the range contraction we observed. We used climate-model predictions and our occupancy model to predict that average occupancy probability across northern Pennsylvania may decline from 0.27 in 2004 to 0.10–0.18 by 2050–2059, depending on the climate model. The range of Snowshoe Hare in Pennsylvania has contracted to regions of Pennsylvania with the coldest winter temperatures and most persistent snowpack, and based on projected climate change, our results suggest further range contraction of Snowshoe Hare in Pennsylvania.

Pennsylvania↗

USGS2004

Survival rates, mortality causes, and habitats of Pennsylvania white-tailed deer fawns

Estimates of survival and cause-specific mortality of white-tailed deer ( Odocoileus virginianus ) fawns are important to population management. We quantified cause-specific mortality, survival rates, and habitat characteristics related to fawn survival in a forested landscape and an agricultural landscape in central Pennsylvania. We captured and radiocollared neonatal (<3 weeks) fawns in 2000–2001 and monitored fawns from capture until death, transmitter failure or collar release, or the end of the study. We estimated survivorship functions and assessed influence on fawn survival of road density, habitat edge density, habitat patch diversity, and proportion of herbaceous habitat. We captured 110 fawns in the agricultural landscape and 108 fawns in the forested landscape. At 9 weeks after capture, fawn survival was 72.4% (95% Cl = 63.3–80.0%) in the agricultural landscape and 57.2% (95% Cl = 47.5–66.3%) in the forested landscape. Thirty-four-week survival was 52.9% (95% Cl = 42.7–62.8%) in the agricultural landscape and 37.9% (95% Cl = 27.7–49.3%) in the forested landscape. We detected no relationship between fawn survival and road density, percent herbaceous cover, habitat edge density, or habitat patch diversity (all P >0.05). Predation accounted for 46.2% (95% Cl = 37.6–56.7%) of 106 mortalities through 34 weeks. We attributed 32.7% (95% Cl = 21.9–48.6%) and 36.7% (95% Cl = 25.5–52.9%) of 49 predation events to black bears ( Ursus americanus ) and coyotes ( Canis latrans ), respectively. Natural causes, excluding predation, accounted for 27.4% (95% Cl = 20.1–37.3) of mortalities. Fawn survival in Pennsylvania was comparable to reported survival in forested and agricultural regions in northern portions of the white-tailed deer range. We have no evidence to suggest that the fawn survival rates we observed were preventing population growth. Because white-tailed deer are habitat generalists, home-range-scale habitat characteristics may be unrelated to fawn survival; therefore, future studies should consider landscape-related characteristics on fawn survival.

Pennsylvania↗

USGS2003

Evaluation of an expandable, breakaway radiocollar for white-tailed deer fawns

We evaluated an expandable, breakaway VHF radiocollar design for use on white-tailed deer (Odocoileus virginianus) from birth to about 1 year of age. A similar collar design has been used on caribou (Rangifer tarandus), but we found that the collar did not expand quickly enough to accommodate increase in neck circumference of fawns during the first 2 months of life. Consequently, we modified the stitching pattern so that the first expansion fold opened faster. We monitored performance of this modification on free-ranging and captive fawns. Also, we collected data on neck growth in fawns to document design requirements of expandable collars for white-tailed deer. Mean neck circumference at ???14 days of age of free-ranging fawns in Pennsylvania was 17.8 cm (SD=1.67, n=62) for males and 17.3 cm (SD=1.50, n=52) for females. Based on measurements of captive fawns, neck circumference increased 8.8 cm from birth to August, 2.5 cm from August to October, and 2.6 cm from October to March. Observations of captive fawns fitted with dummy radiocollars indicated that collars expanded when needed and caused no apparent discomfort to fawns. We detected no problems with use of 86 collars on 113 free-ranging fawns for >270 days and recovered radiocollars expanded as designed. The elastic collar material failed on 3 collars (3%) after 142, 207, and 226 days on fawns, and 1-5 radiocollars (???4%) were cast by fawns. Our modification to this radiocollar design reduced fawn discomfort or suffering, allowing researchers to better comply with principles of the Animal Welfare Act.

Wildlife Society Bulletin↗