Can supplemental food increase winter survival of a threatened cottontail rabbit?

Populations of New England cottontails (Sylvilagus transitionalis) have declined substantially in recent decades in response to habitat loss and fragmentation. Among some remnant populations, cottontails occupy small patches of thicket habitat where they experience high mortality rates as a consequence of limited food during winter. This limitation causes rabbits to forage away from cover where they are exposed to predators. Although conservation efforts are emerging to reverse the decline of New England cottontails, most are directed toward improving long-term viability by increasing the abundance of suitable habitats. Such efforts do little to improve the short-term survival of remaining cottontails. To address this immediate need, we evaluated the use of supplemental food as an approach to improve overwinter survival rates. We speculated that by positioning feeders in close proximity to escape cover, rabbits would be less vulnerable to predators. We evaluated this approach using eastern cottontails (Sylvilagus floridanus) as a research surrogate because this species is readily available and has similar habitat requirements to New England cottontails. Transmitter-equipped eastern cottontails were randomly assigned to either a fed or unfed group. Remotely-triggered cameras were also used to gauge use of feeders by cottontails and visits by other species. Winter survival rates were substantially greater for fed rabbits (70%) than for unfed rabbits (32%). Cameras revealed that rabbits were the most frequent consumer and that there was only limited carnivore activity near feeders. We conclude that supplemental feeding may improve survival of remaining New England cottontails as efforts to increase habitat availability continue to develop.     

Characteristics of occupied habitats and identification of sites for restoration and translocation of New England cottontail populations

Since 1960 the range occupied by New England cottontails (NEC, Sylvilagus transitionalis) in the northeastern United States has declined dramatically. Populations in some regions are known to be vulnerable to extirpation, but little was known about the status of populations in most areas. A recently conducted (2000-2004) range-wide survey identified five disjunct populations within approximately 14% of the historic range of NEC. We incorporated the results of this survey into a geographic information system to examine habitat features associated with remnant populations of NEC at two spatial scales. The regional scale characterized habitats within our survey sample units, 7.5 min topographic quadrangles (quads, ∼40 × 10 km) that were occupied by NEC or vacant. The landscape scale described habitats within a 1-km radius of occupied patches and an equivalent sample of vacant patches. At the regional scale, northeastern and southeastern populations were associated with human-dominated habitats with a greater abundance of developed and disturbed lands, less forest coverage, more edge habitats, and less snow fall than unoccupied quads. Landscapes occupied by NEC in these regions were characterized by a greater abundance of potential dispersal corridors than unoccupied landscapes. In contrast, quads occupied by NEC in the southwestern portion of the historic range were in rural areas that were dominated by forests and agricultural fields. At the landscape scale, southwestern populations were affiliated patches of habitat surrounded by more agricultural lands than patches that were not occupied by NEC. Logistic regression models were then developed to identify habitats suitable for restoration or translocation within each region. We suggest that initial restoration efforts be directed toward expanding existing populations of NEC. Next, habitat connections should be developed among these populations. Finally, new populations should then be established via translocation in portions of the historic range that are vacant. In addition to promoting New England cottontails, management of early-successional and shrub-dominated habitats in the northeastern United States will benefit other taxa of conservation concern that are dependent on these habitats.     

The rise and fall of bobcat populations in New Hampshire: Relevance of historical harvests to understanding current patterns of abundance and distribution

Harvest records reveal that populations of bobcats (Lynx rufus) in New Hampshire have undergone substantial changes during the past 200 years. In the 1800s, a nearly continuous bounty program resulted in annual harvests that averaged ∼30 bobcats. Harvests increased in 1915, and fluctuated from 100 to 400 bobcats during the 1920s through the 1950s. In 1959, harvests peaked at 421 and then rapidly declined. By 1970, payment was made on only 10 bobcats, and legal status was changed from nuisance animal to game species in 1973. In 1989, trapping and hunting seasons were closed and bobcats were designated a protected species. After 15 years of protection, populations of bobcats seem to be remaining at modest levels. To understand what factors may have contributed to the remarkable rise and fall of bobcat populations, we compared the temporal distribution of harvests to comments by early naturalists, legislation to control bobcat abundance, and historical changes in land use. We then used two approaches with a geographic information system to identify the environmental features that may affect present-day populations. The empirical approach relied on a comparison of landscape characteristics associated with recent (1990-2004) observations of bobcats to characteristics found at a comparable set of random locations. We also examined the characteristics of townships that yielded the majority of historical bobcat harvests (1931-1965) and developed a process-oriented model to rank present-day habitat suitability. The irruption of bobcat populations coincided with the availability of early-successional habitats as abandoned agricultural lands reverted to second-growth forests during the first half of the 20th century. Likewise, bobcat populations rapidly declined as these forests matured and no longer supported abundant prey, especially New England cottontails (Sylvilagus transitionalis). Our efforts to identify habitat features associated with present-day populations had mixed results. The empirically derived model correctly classified only 52% of recent bobcat locations, whereas the process-oriented model indicated that nearly 88% of recent bobcat observations were associated with sites that were ranked at high suitability. The results of this study demonstrate the utility of information on historical harvests when addressing questions on the status of contemporary wildlife populations.