Breeding season ecology of translocated northern bobwhite in the Mid-Atlantic and the effects of forest management on breeding songbird communities in the New Jersey Pine Barrens
Date
2021
Authors
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Publisher
University of Delaware
Abstract
I herein evaluated whether landscape connectivity and patch size are important in fostering bobwhite translocation success, especially for long-distance interregional bobwhite translocations (Chapter 2). I translocated 508 radio-collared northern bobwhites from northern Florida and southern Georgia to small, fragmented properties on the eastern shore of Maryland and large, contiguous properties in southern New Jersey, USA. Breeding season (182-day post release) survival varied among sites, and was higher at the two New Jersey release sites (0.344 [CrI = 0.281, 0.408, n = 145]; 0.402 [CrI = 0.340, 0.465, n =176]) than at the two Maryland sites (0.212 [CrI = 0.160, 0.268, n = 20]; 0.282 [CrI = 0.172, 0.412, n = 167]). Site fidelity, maximum dispersal distances, and home range sizes were lower at the smaller, fragmented Maryland properties than the larger New Jersey properties. I recommend that current policies and procedures on translocation be updated to incorporate differential post-release survival patterns, due to landscape context and patch connectivity, when evaluating potential release sites for translocation purposes. Given the reduced bobwhite survival outside target release areas and the correlation between property size and site fidelity, larger sites that have a high degree of connectivity should be favored over those smaller and with lower connectivity of essential habitat features. ☐ Further, I described and evaluated the handicapped founder hypothesis in the context of bobwhite translocation (Chapter 3). I found support for the handicapped-founder hypothesis with regard to nest production, nest success, and overall fecundity. The site-specific proportion of translocated hens that produced ≥1 nest ranged from 0.200 (SE = 0.048) to 0.500 (SE = 0.158) nests/hen. Nest daily survival rate (DSR) was lower at the New Jersey sites than the Maryland sites, with site-specific DSR ranging from 0.878 (85% CrI = [0.820, 0.931]) to 0.972 (85% CrI = [0.947, 0.991]). Overall, nest production was stunted due to high post-release adult mortality and the truncated nesting season typical of northern latitudes. Adjusting translocation stocking density rate (birds/ha) and release timing may maximize the number of birds alive during the peak of nesting season. Overall fecundity was insufficient to facilitate population growth, which illustrates the importance of refining and adapting the existing translocation methodology to be regionally specific. These vital rate estimates and should be used to guide future translocations within the Mid-Atlantic and provide perspective for this population restoration technique range wide. ☐ Finally, I found evidence that forest management practices that traditionally benefit bobwhite within the New Jersey Pine Barrens collectively benefited multiple suites of regionally significant upland breeding birds (Chapter 4). During 2012, 2013, 2016, and 2017, I conducted repeat-visit point counts (n = 1,800) for breeding songbirds across 75 control and 75 treatment sites within the NJPB. I constructed a hierarchical community abundance model within a Bayesian framework for Bird Conservation Region (BCR) 30 priority upland birds (N=12) within three species suites: Forested Upland, Scrub-Shrub/Early Successional, and Grassland. At the community level, I found a negative relationship between bird abundance and live tree basal area (βbasal = −0.23, 95% CrI = [−0.40, −0.09]). I recommend open forest management that specifically targets basal areas between ~0–15 m2/ha via selective thinning, shelter cutting, and small-scale clear cutting. Mechanical treatment and prescribed burning would produce such conditions and have the added benefit of reducing fuel loads across this ~4,500 km2 landscape.
Description
Keywords
Colinus virginianus, Habitat managament, Northern bobwhite, Songbirds, Survival, Translocation