Factors Influencing Survival of Radiotagged and Banded Northern Bobwhites in Georgia

Abstract

Numerous studies of behavior and ecology of northern bobwhites (Colinus virginianus) have depended on radiotagging and telemetry for data collection. Excluding the presumably short‐term effects of trapping, handling, and attaching radiotransmitters, researchers often assume that little bias is associated with estimating survival and behavioral parameters associated with this technique. However, researchers have not adequately examined these effects on organisms being investigated and have thus assumed demographic information obtained from such methods are valid. In light of this conjecture, it is imperative to evaluate methodological assumptions to ensure research is statistically valid and biologically meaningful. Therefore, we used Burnham's model and program MARK to analyze survival estimates of individually banded and radiotagged bobwhites during an 8‐year period (1997–2004) consisting of 6,568 individuals (2,527 radiotagged) via combined analysis of mark—recapture, dead recovery (via harvest), and radiotelemetry data to test the effects of radiotransmitters on bobwhite survival. We also compared band—recapture survival estimates to Kaplan—Meier survival estimates, and we examined the effects of various other factors (e.g., temporal, spatial) on bobwhite survival. Based on Akaike's model selection criterion, the best model including the radiotransmitter covariate (Akaike's Information Criterion adjusted for small sample size bias and overdispersion relative value = 0.72) did not explain more of the variation in survival than models without this effect. Thus, we found the effect of radiotransmitters as negligible. Bobwhite survival varied relative to spatial (e.g., site), temporal (e.g., yr and season), and gender effects. Average annual survival for the 8‐year period was 22.76% (1.50 SE) for banded‐only and 21.72% (1.49 SE) for radiotagged birds. Survival rate varied annually, ranging from 12.42% (7.51 SE) to 37.16% (8.27 SE), and seasonally, ranging from 23.82% (2.71 SE) to 65.06% (3.23 SE); however, between group (banded‐only, radiotagged) survival differences were still inconsequential. We conclude that for our study, radiotelemetry provided reliable survival estimates of an intensively managed bobwhite population, where supplemental food was provided, and this information provided useful data to make practical habitat management decisions. We believe that future radiotelemetry studies would benefit as a whole if researchers conducted similar analyses prior to presenting their results from radiotelemetry data, especially for populations that are more food limited.

Aspects of northern bobwhite ecology on south Florida US pastureland

“…The survival rates derived from this study are lower estimates from those in a high-quality habitat (Palmer and Wellendorf 2007;Terhune et al 2007), but higher than those reported in areas of limited habitat (Burger et al 1995a;Corteville 1998). The analysis showed weak relationships between bobwhite breeding season survival and the explanatory variables-confidence intervals included zero for the parameter estimates.…”

Guidelines for the re-introduction of Galliformes for conservation purposes

“…Researchers should also design studies which examine the effect of banding and radio-tagging on individuals, and also evaluate which methods provide the most reliable demographic data (Terhune et al, 2007;Palmer and Wellendorf, 2007;Buner and Schaub, 2008). These devices should be fitted a couple of weeks before the birds are released to allow full acclimatisation to them.…”

“…Bobwhite quail: radio-transmitters, autumn population abundance counts (quadrat and point) have been used (Wellendorf et al, 2004;Wellendorf and Palmer, 2005), as has mark-recapture via trapping (Terhune et al, 2006a, b;Terhune et al, 2007;Palmer and Wellendorf, 2007). Malleefowl (from Sims, 2000): 24 birds out of a total of 67 released were radio-tagged and tracked for a few days to six months post-release.…”

Habitat influences Northern Bobwhite survival at fine spatiotemporal scales

“…Northern Bobwhites are characteristically poor dispersers (Lehmann 1946, Murphy and Baskett 1952, Smith et al 1982) that exhibit strong seasonal selection for habitats (e.g., Williams et al 2000, Lohr et al 2011 and have low annual survival driven by diverse predator assemblages (Burger et al 1994, Rollins and Carroll 2001, Cox et al 2004, Terhune et al 2007). Life-history theory predicts that low survival in r-selected species should have less influence on population growth rates than breeding productivity (Saether andBakke 2000, Stahl andOli 2006), which has been supported with empirical research from Northern Bobwhite populations at southern latitudes (DeMaso et al 2011).…”