Can at-risk species serve as effective conservation surrogates? Case study in northeastern US shrublands

Targeted, single-species management and ecosystem-based management are
generally considered disparate conservation approaches. In imperiled
ecosystems, these approaches may be complementary, when habitat management
for targeted at-risk species provides broad ecosystem benefits through an
umbrella or surrogate species effect. In the northeastern United States,
extensive management has been ongoing since 2011 to restore declining
habitat for an at-risk shrubland habitat specialist, the New England
cottontail (Sylvilagus transitionalis), with the goal that other
shrubland-obligate wildlife will also benefit; yet the efficacy of these
efforts has not been evaluated. In this study, we assessed whether habitat
management targeting New England cottontail provides conservation benefits
for shrubland-obligate birds. Specifically, we (1) identified
shrubland-obligate birds that are indicative of the microhabitat
conditions and habitat types suitable for New England cottontails, and (2)
determined microhabitat and patch-level influences on shrubland bird
occupancy at sites occupied by or managed for New England cottontail.
Through avian point count surveys and indicator species analyses, we
identified 12 shrubland-obligate bird species on patches occupied by New
England cottontail and in microhabitat conditions suitable for New England
cottontail. Occupancy models for five shrubland bird species further
identified species-specific habitat associations. Generalized linear
models showed that shrubland bird species richness was positively
associated with herbaceous vegetation and low shrubs, indicating that
shrublands managed for the purpose of cottontail colonization can also
benefit a suite of shrubland birds before the habitat is dense enough to
provide cover for cottontails. Our findings show that managing habitat for
New England cottontail on a variety of site types can maintain a range of
microhabitat conditions to support a high diversity of shrubland-obligate
birds. These findings provide evidence for broad ecosystem benefits of
managing for New England cottontail and exemplify the value of at-risk
habitat specialists as conservation surrogates in imperiled ecosystems.