Survival and density of New England cottontail and Eastern cottontail

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.