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Survival and density of New England cottontail and Eastern cottontail

Citation

Cheeseman, Amanda (2021), Survival and density of New England cottontail and Eastern cottontail, Dryad, Dataset, https://doi.org/10.5061/dryad.3bk3j9khq

Abstract

Habitat quality regulates fitness and population density, making it a key driver of population size. Hence, increasing habitat quality is often a primary goal of species conservation. Yet assessments of fitness and density are difficult and costly to obtain. Therefore, species conservation often uses “best available science”, extending inferences across taxa, space or time, and inferring habitat quality from studies of habitat selection. However, there are scenarios where habitat selection is not reflective of habitat quality, and this can lead to maladaptive management strategies. The New England cottontail (Sylvilagus transitionalis) is an imperiled shrubland obligate lagomorph whose successful recovery hinges on creation of suitable habitat. Recovery of this species is also negatively impacted by the non-native eastern cottontail (Sylvilagus floridanus), which can competitively exclude New England cottontails from preferred habitat. Herein we evaluate habitat quality for adult and juvenile New England and eastern cottontails using survival and density as indicators. Our findings did not support selection following an ideal free distribution by New England cottontails. Instead selected resources, which are a target of habitat management, were associated with low survival and density and pointed to a complex tradeoff between density, survival, habitat, and the presence of eastern cottontails. Further, movement distance was inversely correlated with survival in both species, suggesting that habitat fragmentation limits the ability of cottontails to freely distribute based on habitat quality. While habitat did not directly regulate survival of juvenile cottontails, tick burden had a strong negative impact on juvenile cottontails in poor body condition. Given the complex interactions among New England cottontails, eastern cottontails, and habitat, directly assessing and accounting for factors that limit New England cottontail habitat quality in management plans is vital to their recovery. Our study demonstrates an example of management for possible ecological trap conditions via the application of incomplete knowledge.

Methods

Cottontails were live-trapped using box traps. Captured individuals were used to assess capture per unit effort as a measure of density and affixed with radio transmitters to determine factors influencing survival. Cottontails were tracked 1-3 times weekly and their locations were related to grid-based vegetation surveys of habitat across sites.

Usage Notes

Missing values were filled with the mean. 

Funding

New York State Department of Environmental Conservation, Award: 66287