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Whip-poor-will Prey Availability and Foraging Habitat: Implications for Management in Pitch Pine / Scrub Oak Barrens Habitats

Recently, the Whip-poor-will (Caprimulgus vociferous) has become focus of considerable conservation concerns as the result of evidence indicating significant population declines throughout its breeding range (Veit and Petersen 1993). The lack of quantitative data concerning much of this species natural history has delayed recovery efforts and is a fundamental shortcoming in forming effective conservation strategies. Current surveys show Pitch Pine (Pinus rigida) / Scrub Oak (Quercus illicifolia) Barrens (PPSO) as habitat with high numbers of Whip-poor-wills relative to other forest types found throughout the northeastern United States (Cavanaugh in Cink 2002), so we focused our study in these habitats in an attempt to 1) identify habitat selection within PPSO, and 2) determine characteristics of PPSO that make it relatively high quality habitat. Our Study was conducted during the 2005 and 2006 breeding seasons at the Massachusetts Military Reservation on Cape Cod, Massachusetts, USA. We used mist nets to capture adult Whip-poor-wills and affix radio-transmitters for locating individuals during night hours, using triangulation techniques. A kernel analysis of these locations was used to estimate the home range of each individual, where structural characteristics of vegetation was measured, for use in habitat selection analyses. Prey availability was estimated using captures from light traps (Leroy Koehn design, Georgetown, KY) with UV bulbs. Light traps were run on 12 different nights in each habitat during both years of the study. We assessed diet from fecal samples collected at day roost locations used by radio-marked individuals on a daily basis. Samples were dissected under a 22x stereoscope with prey fragments identified to the family when possible. Generalized Linear Mixed Models were used to model habitat selection from structural variables of the habitat collected at used and random locations within the home range, while a compositional analysis of habitat use was also done by comparing the amount of radio-locations in each habitat type to the total amount of that habitat found within the home range. A compositional analysis was also used to test for prey selection. Data from 15 Whip-poor-wills were used in our analyses. Univariate and multivariate statistics showed that there was no difference in vegetation structure between used and random sites. Ground cover was the best predictor of habitat use identified by the GLMM, but was still inefficient for determining habitat use. However, the compositional analysis of habitat use did show a preference of pitch pine – oak forests over pitch pine – scrub oak communities. The fecal analysis showed Whip-poor-wills preferred moths over scarab beetles, and “other” prey items which consisted mainly of beetles other than scarabs, along with neuropterans. Light trap captures showed prey was distributed equally among habitats at the MMR. Although our study did not show any strong relationships between vegetation structure and habitat selection, this may not be the case in habitats of lesser quality (i.e. not PPSO). The habitat preference rank from the compositional analysis directly correlated with the amount of ground cover found in each habitat, which is supporting evidence that ground cover may be an important factor in selecting habitat. Low amounts of ground cover may allow Whip-poor-wills to detect and capture prey more easily, as well as provide open area for an easy escape route from potential predators. Land management techniques such as prescribed burning that reduce understory are recommended treatments to increase habitat quality for Whip-poor-wills.