An evaluation of northern bobwhite translocation to restore populations

Abstract

Northern bobwhite (Colinus virginianus) populations have been declining in Texas during the last 2 decades. This decline also is occurring in areas with apparently ample habitat such as the Rolling Plains of Texas, USA. The goal of our study was to examine the efficacy of translocating wild-trapped bobwhites into recently depopulated areas in the eastern Rolling Plains as a method of restoring population size. Our objectives were to document survival (spring-summer and annual), reproductive efforts, and site fidelity of translocated bobwhites and compare relative abundance of bobwhites between release and control sites to evaluate the efficacy of translocation. We translocated 409 wild bobwhites (n ¼ 186 radio-marked F) to 2 sites in Shackelford and Stephens counties, Texas, during March 2013 and 2014. Spring-summer (Mar-Sep) survival ranged between 0.32 and 0.38 (n ¼ 186 bobwhites), and annual survival ranged between 0.19 and 0.23 (n ¼ 186 bobwhites) during 2013-2015. Seventy-four percent of translocated females that entered the nesting season (i.e., May 1; n ¼ 112 bobwhites) produced a nest, resulting in 125 nests with an apparent nest success of 46.1% and a nesting rate of 1.1 AE 0.1 (SE) nests/female. Site fidelity post-translocation was moderate to high; 67.7% (n ¼ 44 bobwhites) and 85.1% (n ¼ 40 bobwhites) of translocated bobwhites did not disperse >2 km from their release point during the summers of 2013 and 2014, respectively. Despite this strong demographic performance, relative abundance of bobwhites did not differ between the release and control sites after 2 years as indexed by covey-call counts (2.7 AE 0.6 vs. 3.0 AE 1.2 coveys/point, respectively; P ¼ 0.71) and helicopter surveys (0.9 AE 0.2 vs. 0.7 AE 0.2 bobwhites/km, respectively; P ¼ 0.64). Thus, translocation of bobwhites failed to increase the bobwhite population beyond that of the control during this study. Future translocation research should aim to increase translocation success by investigating methods for increasing survival during the 1-month period following translocation (e.g., soft-release, vitamin E and selenium injections) and for improving site fidelity using conspecific attraction. Future research should incorporate genetic measures to assess genetic contribution of translocated individuals to improve evaluation of translocation success. Ó 2017 The Wildlife Society.

Landscape Connectivity Influences Survival and Resource Use following Long‐Distance Translocation of Northern Bobwhite

“…Daily survival rate was 6–8% lower than for long‐term mark‐recapture studies from the source sites of the translocated birds in this study (Palmer and Wellendorf 2007, Terhune et al 2007) during the initial 2 weeks following release. An estimated 14–29% of translocated bobwhites died during the first 2 weeks following release, similar to the 30% mortality rate reported within the first month following release by Downey et al (2017). This temporal pattern contrasts exploratory survival analyses by Terhune et al (2010) in which survival of translocated bobwhites was higher in the first month following release compared to subsequent months.…”

“…Across all study sites, breeding season survival was moderate to low. Breeding season survival estimates for translocated bobwhites at Chino Farm, Home Farm, and Sim Place (0.282–0.402) were within the range commonly reported in bobwhite telemetry studies (Burger et al 1995, Sisson et al 2009, Lohr et al 2011), including some comparable translocation research (Liu et al 2000; Terhune et al 2006 b , 2010; Downey et al 2017) but remained on the lower end of the spectrum. The highest breeding season survival rates, observed at Home Farm (0.344) and Sim Place (0.402), were similar to estimates from previous long‐term mark‐recapture studies conducted on stable or increasing populations (Palmer and Wellendorf 2007, Terhune et al 2007).…”

“…For each site and year, we translocated bobwhites at an approximate 1:1 sex ratio. Because of the known logistical constraints associated with long‐distance bobwhite translocation (Downey et al 2017), we made an effort to maximize the synchrony of trapping and translocation. We focused capture timing to the period immediately preceding covey break up (Terhune et al 2006 a ), as determined from field observations of bobwhite behavior on source sites, so that larger groups of bobwhites could be captured.…”

“…Groups modeled as fixed effects were release site (Chino Farm, Home Farm, Sim Place, and Turner's Creek), year (2015–2018), individual bird sex (female vs. male), and age (adult vs. juvenile). We modeled week after release (1–26) as a fixed temporal effect under the assumption that survival varied across weeks in a manner parallel among sites, as has been reported in previous translocation literature (Terhune et al 2010, Downey et al 2017). This allows the revelation of any acute or chronic effects of the translocation process (e.g., handling effects) on survival.…”

“…Although translocation of wild bobwhites has been of interest in recent years, researchers have reported mixed results (Terhune et al 2006 a , b ; Scott et al 2012; Downey et al 2017). The current body of literature, however, is deficient in translocation studies that have replication within years, evaluate long‐distance (>400 km) movement of birds from the source to the recipient sites, or occur in the Mid‐Atlantic region.…”