Conservation and Ecology of Mammals V

Contributed Paper
ROOM: Rooms 18 – Cochiti and 30 – Taos Combined
SESSION NUMBER: 91
 

10:30AM Assessing Snowshoe Hare Distribution and Abundance in the Face of Climate Change
Shawn M. Cleveland; Brian Underwood
The forests of the northeast United States are largely secondary growth and relatively even aged due to broad-scale logging efforts through the early 1900’s and lack of large-scale natural disturbance within the system since. Snowshoe hare (Lepus americanus) are closely tied to both young and old growth forests for shelter and food availability. Snowshoe hare have shown a long-term population decline in NY, and are in need of assessment given their importance as a key prey species for many forest carnivores. This forest dependent species is also closely tied to snow cover as they undergo circannual molt, and as such are highly sensitive to climate change, especially as it relates to the timing and persistence of snow cover. Climate change is forecasted to alter the timing and duration of snowpack in New York, which may negatively affect hare’s ability to evade predation through camouflage- leading to higher predation rates and accelerated range contraction. Reduced snowshoe hare populations and range contraction are expected to have direct, deleterious implications for fisher populations in the Adirondack Region. Consequently, more information is needed about hare abundance and distribution to better manage fisher populations. To address this concern, we used a single season occupancy sampling design to determine the distribution and abundance of snowshoe hare using track surveys in the Adirondack Park Region of Upstate New York. Results suggest that hare occupancy and abundance is closely tied with early successional mixed and conifer forest, suggesting a need for early successional forest management strategies to occur at the landscape scale.
10:50AM Scared to Death: the Lethal Effects of Non-Lethal Predator Exposure
Michael Sheriff
Predators play a critical, top-down role in shaping ecosystems, driving prey population and community dynamics. Traditionally, studies of predator-prey interactions have focused on direct effects of predators, namely the killing of prey. However, more subtle effects of predator exposure on prey physiology and behaviour are being increasingly appreciated. Here we exposed female snowshoe hares to a trained dog (simulated predator) for 1min every other day for 2 weeks and show, for the first time in a mammal (the snowshoe hare), that the risk of predation can itself be lethal to adult individuals. In addition to reducing adult survival, predator exposure during gestation also reduced offspring survival after the period of risk had ended. Overall, the predator-exposed group experienced a substantial decrease in number, while the control group increased. Challenges remain in determining the importance of risk-induced mortality in natural field settings; however, our findings show that non-lethal predator encounters have the potential to substantially influence survival and reproductive output in this species. These results have important implications for our understanding of the indirect effects of predators on prey, and transgenerational effects of risk.
11:10AM A Survey of the Parasites of the Native New England Cottontail, the Introduced Eastern Cottontail and Cottontail Habitat in the Lower Hudson Valley
Samantha L. Mello; Jonathan B. Cohen; Christopher M. Whipps
Historically common throughout the northeastern United States, the New England cottontail (Sylvilagus transitionalis) (NEC) has experienced declines throughout its range and is now only found at five geographically separated populations at the edges of its historic range. In the 1900s, eastern cottontails (Sylvilagus floridanus) (EC) were introduced to the northeastern United States and invaded NEC habitat potentially creating a host for species and increasing the diversity of these parasites in the NEC range. We studied ticks of NEC and EC and the diversity of a potentially pathogenic protozoan endoparasite (Eimeria spp.) of the two cottontail species in sites throughout the Lower Hudson Valley of New York. Pellets were collected from trapped rabbits and placed in potassium dichromate promoting sporulation of the oocyst. Forty-six fecal samples were examined with thirty unique NEC and ten unique EC. Forty-two fecal samples had Eimeria species. Ectoparasites visible to the naked eye were counted and a representative sample was collected for species identification. Ectoparasites were examined on 148 rabbits with 102 NEC and 46 EC. Species of ticks found were: Ixodes scapularis, Dermacentor variabilis, Rhipicephalus sanguineus, Ixodes minor, and Haemaphysalis leporispalustris. EC had more ticks for their body mass than NEC. To investigate tick species in NEC habitat, we tick dragged five sites. We analyzed the relationship between tick density and different vegetation types and seasons using Bayesian regression, and time within season. The findings suggest no significant difference in tick abundance among four habitat types; however, tick density was much lower at our mostly native-vegetation site than other sites. Ticks decreased over the spring and declined over the fall. Results from this study will provide insight into parasite composition of the two cottontail species, cottontail habitat and the potential role of parasites as a limiting factor for the New England cottontail.
11:30AM Movement and Dispersal in a Rare Native Lagomorph And a Common Invasive Competitor: Implications for Metapopulation Management
Amanda E. Cheeseman; Jonathan B. Cohen; Sadie J. Ryan; Christopher M. Whipps
As human activity increasingly fragments landscapes, the focus of wildlife management has increasingly been placed on dispersal of species that exist in metapopulations. One such species, the New England cottontail (NEC, Sylvilagus transitionalis) is an imperiled shrubland obligate. NEC face numerous challenges to recovery including habitat loss due to anthropogenic activity and natural maturation of its ephemeral habitat, decreasing population connectivity, and competition with non-native eastern cottontails (EC, S. floridanus). Although much emphasis is given to the management of NEC within a metapopulation framework, little is known about the dispersal capabilities of NEC and sympatric EC. Our goal was to compare the frequency and individual-specific propensity of NEC for exploratory and dispersal movements and the distance travelled during such movements between cottontail species, sexes, age classes, and seasons. From 7,190 movement observations of 204 individuals, we observed 19 dispersal events. Dispersals ranged from 0.25 – 3.88 km. We observed no dispersal of female NEC, and present evidence for male biased dispersal in NEC and sympatric EC. There was no support for systematic juvenile dispersal in NEC or EC in contrast to other lagomorphs. While rates of exploratory movement were greater in the leaf on (breeding) season, a majority of dispersals occurred during late winter and early spring, suggesting the onset of dispersal may be forced as a result of resource scarcity. We did not detect a difference in movement rates between cottontail species. Our findings suggest that the present connectivity of habitat patches may be too low to permit sustainable rates of patch colonization. Habitat management should be conducted within 1 km of existing NEC-occupied patches. Translocations and reintroductions may need to be considered to ensure long term persistence of NEC metapopulations, given low rates of female dispersal and to ensure patches are not first colonized by EC.
11:50AM Restoration of a Rare Lagomorph: Current Status and Approach for Monitoring Remnant New England Cottontail Populations
Adrienne I. Kovach
The New England cottontail is one of the most vulnerable of the many declining shrubland-dependent species and of high conservation concern in the northeastern United States. As a result of extensive recent habitat decline and range contraction, remnant populations today occur in <14% of the species’ historical range in geographically and genetically distinct metapopulations, where they face consequences of isolation and fragmentation. Despite a widely acclaimed, collaborative, conservation initiative, culminating in the 2015 decision that the species did not warrant protection under the ESA, much uncertainty remains about the species’ viability and population status. Here we present trends resulting from a decade’s worth of monitoring (2007-2016), using a systematic, intensive, noninvasive genetic sampling effort. Fecal pellet surveys were conducted on habitat patches in 2-km sampling grids in areas of prior occupancy and 4-km grids in surrounding areas. New England cottontail pellets were identified from cytochrome b genetic sequences and unique individuals by multilocus microsatellite genotypes. Our findings suggest ongoing population declines of 20-50% across the species’ range. We developed a metapopulation-based monitoring approach that integrates occupancy surveys with spatial mark-recapture abundance estimation. This approach is aimed to characterize patch dynamics of extinction and recolonization and track trends over time in the status of cottontails in genetically distinct metapopulations. We present this new protocol and describe its application for monitoring responses to restoration efforts, including translocations of rabbits from a captive breeding program. Despite high detection rates, power to detect trends will be constrained for some metapopulations by low occupancy rates and limited number of suitable habitat patches, but can be overcome by carefully targeting surveys and inference towards the known areas of current occupancy. Implementation of this monitoring program over time should lead to improved management for this species of conservation concern.

 

Contributed Paper
Location: Albuquerque Convention Center Date: September 27, 2017 Time: 10:30 am - 12:10 pm