Effects of road baiting on home range and survival of northern bobwhites in southern Texas

Abstract

An increasingly common practice in southern Texas is baiting roads with grains such as milo (Sorghum spp.) and corn (Zea mays) to facilitate northern bobwhite (Colinus virginianus) harvest. However, baiting roads might have a negative impact on bobwhite survival by increasing predation or harvest rates. The objective of this project was to determine the effects of road baiting on bobwhite survival, home‐range size, and predator abundance. The project involved 2 study sites (baited=treatment and nonbaited=control) that were monitored over 3 periods, pre‐baiting (September‐October), baiting (November‐December), and post‐baiting (January‐February), during 2001–2002 and 2002–2003. We captured, radiomarked, and monitored bobwhites (n = 60 [treatment site]; n = 58 [control site]) in Jim Hogg County, Texas. We assessed relative abundance and activity of avian and mammalian predators using scent‐station and road surveys, respectively. The effects of baiting roads varied between years. During 2001–2002, a relatively dry period, bobwhite survival (Š = 1.00±0.00 [control site]; Š = 0.68±0.10 [treatment site], P=0.01), covey home‐range size (15.6±1.43 ha [control site]; 12.7±2.22 ha [treatment site], P=0.046), and covey distance to roads (193±24.6 m [control site]; 95±41.57 m [treatment site], P≥0.001) were lower on the treatment site during the feeding period in contrast to the control site. A nonsignificant trend was noted for higher avian predator abundance on the treatment site during the feeding period. During 2002–2003, a relatively wet period, no difference in bobwhite survival, covey home‐range size, and covey distance to roads was found between sites and time periods due to baiting, and no trend in predator abundance was found between pastures and time periods. The practice of baiting ranch roads does not appear to benefit bobwhites in southern Texas, and during dry conditions the practice might be detrimental to bobwhite numbers by lowering survival. Baiting or other methods of dietary supplementation are more likely to benefit bobwhites in more northern climates with colder winters.

Patterns of space and habitat use by northern bobwhites in South Florida, USA

“…Efforts to reverse the decline in the bobwhite population are currently underway; our goal was to assist the Florida Fish and Wildlife Conservation Commission in this effort by providing data on space and habitat use by bobwhites on the WMA. Characteristically, bobwhites occupy home ranges as small as ≤5 ha in excellent habitat (Sisson et al 2000;Wiseman and Lewis 1981) and ≤40 ha in good habitat (Bell et al 1985;Dixon et al 1996;Guthery et al 2004b;Haines et al 2004;Terhune et al 2006). The mean annual home range size in our study area was 88.43±6.16 ha, which is substantially larger than most previously reported bobwhite home ranges.…”

“…The same pattern was observed for winter home ranges as well. Food plots and supplemental feeding are widely used practices for managing bobwhite populations in North America (Guthery et al 2004b;Haines et al 2004;Townsend et al 1999). Our results, along with those of Guthery et al (2004b), suggest that bobwhite home ranges may be influenced by food availability and that bobwhites inhabiting poor quality habitat (or within a site, during seasons of lower food availability) would typically need larger home ranges to satisfy their resource needs (Sisson et al 2000;W.E.…”

“…Palmer, Tall Timbers Research Station, 2009, personal communication). The effects of supplemental food on home range size may, however, vary depending perhaps on local habitat conditions (e.g., Haines et al 2004).…”

“…Annual home ranges were estimated for birds that had ≥30 radiolocations spanning at least 3 months in each season. The literature suggests that the number of locations used to estimate home ranges in our study is adequate (Haines et al 2004;Hiller et al 2007;Taylor et al 1999b) and also reflects a trade-off between the number of radiolocations per bird as compared to monitoring a large number of birds. On average, individual birds were monitored for 110.52±5.29/ days/year; the average number of locations was 37.90±0.49 (Table 1).…”

Broadcast supplemental feeding and northern bobwhite demographics in Texas

“…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. Notably, The Wildlife Society's position statement cautions against supplemental feed as a panacea, citing the potential to affect gamebird behavior (e.g., intraspecific competition), alter predation rates, facilitate disease transmission, and affect non‐target species (Sonant and Maestro ).…”