Effects of Prescribed Fire on Northern Bobwhite Nesting Ecology

Abstract

ABSTRACTRepeated 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 = 0.75%, range = 0–3%) of the study area was burned during the 2016 nesting season (3 June to 3 September), 4% (weekly = 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 = 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.