The longleaf pine (Pinus palustris) ecosystem is one of the most endangered in the world and provides habitat for many rare species, including the Bachman’s sparrow (Peucaea aestivalis). Although male Bachman’s sparrow ecology in the fire-maintained longleaf pine ecosystem is well studied, much less is known about the breeding ecology of females. Accordingly, we determined female Bachman’s sparrow habitat selection, breeding season range size, and survival rate on Fort Bragg Military Installation in North Carolina, USA. We attached radio-transmitters to female sparrows during the breeding season (April to June) in 2014-2016. Each year, we recorded locations of marked females every 2-4 days, and calculated range size for individuals that had at least 10 locations (n=31). In 2016, we measured vegetation at 10 locations and 10 random points for each of 10 transmitted female sparrows. We compared vegetation structure at observed and random locations using generalized linear mixed effect models. We created 23 multivariate models and ranked them using Akaike Information Criterion corrected for small sample size. We calculated survival probability using the Kaplan-Meier Method.
Results/Conclusions
Breeding season range size was 1.96 ha (SE = 1.15), which is consistent with previous studies of male territory size. The top habitat selection model showed female Bachman’s sparrows selected habitat patches with greater woody shrub cover and intermediate levels of grass cover compared to random locations. Our results differed from previous studies that showed Bachman’s sparrows avoided areas with extensive shrub cover. However, most other studies focused on male sparrow habitat selection, so our results indicate that females may use shrub cover for escape or for foraging more so than males. The probability of female sparrows surviving the breeding season (April-July) was 0.91. Few estimates of female survival exist, but annual male survival estimates range between 0.54-0.68, suggesting the majority of annual female mortality may occur during the non-breeding season. Our results highlight the importance of understanding habitat selection at multiple scales before developing habitat management prescriptions.