Determinants of home-range size of imperiled New England cottontails (Sylvilagus transitionalis) and introduced eastern cottontails (Sylvilagus floridanus)

Abstract

In fragmented habitat, population persistence depends in part on patch quality and patch size relative to home-range size. The imperiled New England cottontail (Sylvilagus transitionalis (Bangs, 1895)) is an obligate user of shrublands in the northeastern United States, a highly fragmented and declining ecosystem. New England cottontail conservation efforts have targeted habitat creation; however, efforts are hindered by a limited knowledge of seasonal space use and its relationship to habitat quality, which could help inform minimum patch-size requirements and implications of competition with non-native eastern cottontails (Sylvilagus floridanus (J.A. Allen, 1890)). To address these uncertainties, we modeled home-range areas for both species as a function of season, patch size, sex, and two indicators of forage and cover availability. Home range was generally inversely correlated with measures of forage and cover resources and the response differed by season and species and did not vary with patch size. Instead, inclusion of matrix habitat within home ranges increased with decreasing patch size, placing individuals within smaller patches at a high risk of mortality. These risks may be mitigated in patches >7 ha and absent in patches >20–25 ha where predicted inclusion of matrix is lower or absent.

Is conservation based on best available science creating an ecological trap for an imperiled lagomorph?

“…Past research addressing habitat quality for New England cottontails has largely focused on studies of habitat use and selection (Brubaker et al., 2014; Buffum et al., 2015; Cheeseman et al., 2018, 2019; Kilpatrick et al., 2013; Litvaitis et al., 2003, 2006; Shea et al., 2019; Tash & Litvaitis, 2007). Demographic studies related to habitat quality have been mostly limited to assessments of survival at their northern range boundary (Barbour & Litvaitis, 1993; Brown & Litvaitis, 1995) where eastern cottontails are still scarce, emphasizing the importance of vegetative cover with high stem densities and the influence of large habitat patches on survival (Barbour & Litvaitis, 1993; Brown & Litvaitis, 1995).…”

Can at‐risk species serve as effective conservation surrogates? Case study in northeasternUSshrublands

“…Given suitable vegetation structure (tall, dense shrubs for cover and winter forage and areas of forbs and grasses for summer forage; Barbour & Litvaitis, 1993; Cheeseman, Cohen, Ryan, & Whipps, 2019; Cheeseman et al, 2018; Dalke & Sime, 1941; Smith & Litvaitis, 2000; Warren et al, 2016), New England cottontails can occupy shrub habitat on a variety of site types from shrub wetlands to dry, upland habitat. Therefore, encouraging tall, dense shrub growth interspersed with herbaceous cover on a variety of site types will also create habitat for a diversity of shrubland‐obligate birds (e.g., YEWAs, Alder Flycatchers, and Song Sparrows on wet sites and PRAWs, Brown Thrashers, and Field Sparrows on dry sites).…”

Separating Proactive Conservation from Species Listing Decisions

“…While this knowledge was known at the time of the listing decision, the prevailing notion was that robust populations in the core of the species’ range––Connecticut and eastern New York––persisted as a stronghold. Since that time, a thorough investigation of population genetics, dispersal, survival and home range of New England cottontails in New York strongly contradicts that notion (Cheeseman, 2017 ; Cheeseman et al, 2019a ; Cheeseman et al, 2019b ). Cheeseman et al ( 2019a ) identified nine genetically distinct and isolated subpopulations, with evidence for low genetic diversity and effective population sizes.…”

“…Since that time, a thorough investigation of population genetics, dispersal, survival and home range of New England cottontails in New York strongly contradicts that notion (Cheeseman, 2017 ; Cheeseman et al, 2019a ; Cheeseman et al, 2019b ). Cheeseman et al ( 2019a ) identified nine genetically distinct and isolated subpopulations, with evidence for low genetic diversity and effective population sizes. Similar concerns exist for populations in eastern and western Connecticut (A. Kovach, unpublished data; McGreevy et al, 2021 ).…”

“…Habitat quality strongly regulates the fitness and growth of populations and is a driver of both survival and density of New England cottontails (Barbour and Litvaitis, 1993 ; Brown and Litvaitis, 1995 ; Cheeseman et al, 2021 ; Villafuerte et al, 1997 ). New England cottontails have strict habitat requirements and their home ranges are typically bounded by low-cover patches, potentially because they suffer high predation rates outside dense cover (Cheeseman et al, 2019a ; Smith and Litvaitis, 2000 ). Prior to the listing decision, New England cottontail studies focused on winter habitat use, identifying patches > 5 ha of dense early successional shrublands with >50,000 stems/ha as high-quality habitat.…”