No abstract

Creating early successional vegetation on working farms can increase northern bobwhite (Colinus virginianus; hereafter, bobwhite) abundance with little reduction in crop production, but specific effects of field border establishment on bobwhite nesting ecology are not well understood. We monitored bobwhite nesting on a 1,740-ha working farm with 19% of property managed for early successional vegetation in southeastern North Carolina, USA. We monitored 133 radio-marked bobwhites from 1 April to 30 September in 2014 and 2015. We modelled nest-site selection by comparing paired nest and random reference sites and modeled effects of habitat covariates on daily nest survival. Forb, shrub, and native warm-season grass cover were greater at nest sites than reference sites with forb cover the strongest predictor of nest-site selection. Bobwhite nested at a greater density in areas managed for fallow vegetation (1 nest/3 ha) than in planted warm-season grasses and forbs (1 nest/5 ha). The daily nest survival rate over 2 years was 0.964 (SE = 0.007), and was not significantly influenced by any modeled covariate. Naïve nest success (nest successes/total nests) was 46.9%. The importance of forbs as nesting cover indicates bobwhite abundance in areas dominated by row-crop agriculture may be limited by low nest initiation from a lack of herbaceous nesting cover. Hence, the creation of fallow herbaceous vegetation on working farms should be prioritized to increase bobwhite reproduction within agricultural landscapes. Furthermore, planting warmseason grasses is not necessary because volunteer forbs and grasses provide as good or better nesting cover and can be less costly to establish.

Efforts to halt the decline of the northern bobwhite (Colinus virginianus; bobwhite) across its distribution have had limited success. Understanding bobwhite habitat requirements across the annual cycle and at varying scales is essential to aid efforts to conserve bobwhites. We monitored radio-tagged bobwhites from 2016 to 2018 on a 165-km 2 portion of Fort Bragg Military Installation in the Sandhills physiographic region of North Carolina, USA, to determine factors influencing non-breeding bobwhite habitat selection at multiple scales. We used generalized linear models (GLM) and generalized linear mixed models to assess bobwhite habitat selection at the microsite scale (the immediate vicinity of an animal) and the macrosite scale (across the study area), respectively, by comparing used points to available random points. At the microsite scale, bobwhites strongly selected areas with greater woody understory cover. Also, bobwhite selection increased with greater forb and switchcane (Arundinaria tecta) cover, but this effect plateaued at 65% forb cover and 50% switchcane cover. At the macrosite scale, bobwhites generally selected areas with greater understory cover within a 200-m radius but avoided areas with >55% understory cover; these areas primarily were located in the core areas of drainages with extensive ericaceous vegetation. Bobwhites selected areas with 3-6 m 2 /ha hardwood basal area in uplands, potentially because of the | Kroeger et al.

Repeated prescribed fire can create and maintain areas with sparse overstory tree cover and a dense grass‐forb‐shrub understory, providing habitat for northern bobwhite (Colinus virginianus; hereafter, bobwhite). Despite potential benefits of prescribed fires for conserving bobwhite habitat, burning during the nesting season may destroy bobwhite nests and reduce available nesting cover. We monitored radio‐transmittered bobwhite (n = 104) from 2016 to 2018 to describe nest‐site selection and determine the risk of nest destruction on a 17,000‐ha North Carolina military installation, Fort Bragg, managed with rotational growing‐season and dormant‐season prescribed fires on an approximate 3‐year return interval. We located 48 nests, of which 8 (16%) were in areas burned the same year, 9 (19%) were in one‐year post fire, 25 (52%) were in 2‐years post fire, and 6 (13%) were in ≥3‐years post fire areas. We compared vegetation composition and structure at nests to nearby random locations and determined bobwhite selected nest sites with greater woody understory and wiregrass cover, lower basal areas of pines and hardwoods, and less distance to the nearest road. Two nests (6.7%) were destroyed during prescribed fires, but success of incubated nests was high (67%). We calculated the overall risk of nest destruction by prescribed fire as the proportion of active nests in areas with ≥3 years since last fire multiplied by the proportion of the study area burned each week. Overall, 11% (weekly truex ̅ = 0.75%, range = 0–3%) of the study area was burned during the 2016 nesting season (3 June to 3 September), 4% (weekly truex ̅ = 0.31%, range 0–2%) of the study area was burned during the 2017 nesting season (5 June to 2 September), and 7.5% (weekly truex ̅ = 0.58%, range 0–5%) of the study area was burned during the 2018 nesting season (3 June to 31 August). We estimated that no more than 0.75% of bobwhite nests across the study site were exposed to fire annually. Most growing‐season fires occurred before the bobwhite nesting season, which limited direct effects of prescribed fire on bobwhite nest survival. However, shifting prescribed fires to later in the growing season to better match the historical lightning season (i.e., after 1 June) would increase the risk of nest destruction. Because bobwhite used older roughs (i.e. areas 2 years since fire) for nesting, shortening the fire return interval to less than 3 years would increase the proportion of nests exposed to fire. Additionally, a shortened fire return interval would decrease available nesting cover, especially in regions with low soil fertility where vegetation change following fire is less rapid than on more productive soils. © 2021 The Wildlife Society.