Date of Award

Fall 2007

Project Type

Thesis

Program or Major

Natural Resources: Wildlife

Degree Name

Master of Science

Abstract

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 range-wide survey of NEC was conducted from 2000 to 2004 to determine the current distribution and status of remnant populations. Because NEC are sympatric with eastern cottontails (Sylvilagus floridanus) and snowshoe hares (Lepus americanus) throughout much of their historic range, identity of resident lagomorphs was based on DNA either extracted from tissue of live-captures or from fecal pellets collected in occupied patches of habitat. A total of 2301 patches of suitable habitat within 287 quads were searched for the presence of NEC. Of these, 162 patches and 87 quads were considered to be occupied. Five disjunct populations were identified in approximately 14% of the historic range of NEC. Forest maturation and fragmentation are the most plausible explanations for the widespread decline of NEC. Contraction of the historic distribution was toward eastern and southern edges where a variety of anthropogenic disturbances (e.g., brushy edges of highways and railroad corridors and idle portions of agricultural fields) provided habitat. Land-use activities (expanding development and limited forest management) within the currently occupied range of NEC suggest a continued decline of suitable habitats.

Spatial information from the range-wide survey was incorporated 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 survey sample units, 7.5 minute topographic quadrangles (quads, ∼40 x 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 and autologistic regression models were then developed to identify habitats suitable for restoration or translocation within each region. The modeling effort identified approximately 740,000 ha of suitable habitat within the historic range of NEC. This included nearly 90,000 ha on conservation or other public lands. A total of 1487 individual sites were identified as potential management targets with 155 ranked as having high value for restoration or translocation. The results 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.

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