Effects of broadcasting supplemental feed into roadside vegetation on home range and survival of female northern bobwhite

Abstract

Declines in northern bobwhite (Colinus virginianus) populations have led landowners in Texas, USA, to develop various management strategies to combat waning abundance. One common management strategy is to provide supplemental feed to bobwhites, despite the paucity of information regarding the effects of supplemental feed on bobwhite space use and survival. We examined survival and home range of bobwhites using the technique of spreading supplemental feed into roadside vegetation in the Texas Rolling Plains. The study sites were divided into 8 (404.6-ha) units randomly designated as treatment (feed provided) or control (feed withheld). Treatment and control units were rotated during the second field season to minimize potential habitat bias. Treatment units received approximately 69.1 kg/km of milo (Sorghum bicolor) twice per month. We captured and radiomarked 197 female bobwhites (82 treatment [48: 2010-2011; 34: 2011-2012], 115 control [64: 2010-2011; 51: 2011-2012]) from autumn 2010 to spring 2012. Females were monitored for location and survival with radiotelemetry 3-4 times/week. Average home-range size was similar on control and treatment units (47.6 ha [8.7 SE] and 46.2 ha [10.3 SE], respectively). We estimated survival rate with the nest survival model in Program MARK. We observed an increase in survival rate on treatment units compared with control units, regardless of year or environmental conditions. Our results suggest that distributing supplemental feed into roadside vegetation positively influences bobwhite survival with no reduction in home range size. Ó 2015 The Wildlife Society.

Broadcast supplemental feeding and northern bobwhite demographics in Texas

“…A single winter storm may result in dramatic population effects when coupled with drought conditions during the spring and summer, which are more common in Texas, when periods of natural food limitations exist (Buckley et al ). Buckley et al () observed feed benefits to bobwhite during these drought periods. Coupled with our results, the survival benefits of food supplementation extend into both climatic extremes.…”

“…To date, no method of feeding has consistently yielded improvements in bobwhite demographics under multiple iterations. Our primary objective was to replicate and substantiate the work by Buckley et al (2015). We predicted the survival of birds would be higher on food-supplemented sites than on our control sites.…”

“…Nutritional deficiencies resulting from the absence of, or limited availability to, quality food resources present challenges to the bobwhite and managers. Food limitations during drought conditions (Guiliano et al , Hernández et al ) and periods of extended snow coverage (Roseberry and Klimstra ), and the increased caloric requirements to thermoregulate during winter (Swanson and Weinacht , Janke et al ), typify periods when bobwhites are unable to meet their energy requirements (Wood et al , Buckley et al ). Guiliano et al () reported that diets low in energy were closely tied to body mass loss and Leif and Smith () acknowledged that when given high energy food sources, quail were better able to respond to changing climactic conditions.…”

“…For many, the supplementation of feed during these periods has seemed a logical step in addressing resource concerns (Hernández et al , Rollins ). Using bobwhites as a model species and survival as a proxy for the overall fitness of individuals, researchers have tested whether supplemental feeding, as a management strategy to address food limitations, can provide appreciable survival benefits for local and regional populations (Ellis et al , Doerr and Silvy , Buckley et al ). Traditionally wildlife managers have used food plots (Joselyn , Robel , Robel et al , Madison et al ), stationary feeders (Dumke , DeMaso et al , Guthery et al ), and road baiting (Haines et al , Hernández et al ), or a combination thereof (Townsend et al ), to improve the survival rates of northern bobwhites or enhance hunting opportunities (Schulz et al ); the results have been mixed with a majority of studies indicating conventional feeding regimes are not a viable strategy.…”

Northern bobwhite population responses to winter weather along their northern range periphery

“…Our results suggest that management and conservation strategies aimed at addressing long‐term population declines of bobwhites throughout the northern tier of their range should address effects of high mortality that attend periods of substantial snow accumulation. We surmise 4 potential management strategies could be employed to abate the influence of winter weather on bobwhites: 1) implementing habitat management to promote cover that confers survival advantages to wintering bobwhites (Janke et al ), 2) fostering high‐density populations that may be more resilient to winter mortality (Williams et al 2003 b , Janke et al ), 3) focusing on improving reproductive output to offset winter losses through breeding‐habitat conservation, or 4) employment of intensive artificial management methods for increasing survival or reproduction (e.g., supplemental feeding; Buckley et al ). High breeding productivity is indeed essential to sustain bobwhite populations in the north (Roseberry and Klimstra ).…”