FINAL REPORT
State of Oklahoma
Grant Number W-82-R
Project Number 005
Grant Title: Upland Game Investigations
Grant Period: July 1, 1991 – June 30, 1997
Project Title: Quail Mortality Study
Project Objective: To identify causes and rates of quail mortality and to investigate relationships between quail mortality, predator abundance, and supplemental feed.
Abstract: We investigated survival and cause-specific mortality of 1,115 radiomarked northern bobwhites (Colinus virginianus) and the effect of supplemental feeding on these population parameters. Reproductive parameters for bobwhites were also estimated. Research was conducted from 1 October 1991 through 1 October 1996 on the Packsaddle Wildlife Management Area (WMA) in western Oklahoma. Thirty-two feeders filled with sorghum were located near the center of every 8.1 ha on the 283.3 ha treatment area. The control treatment was 283.3 ha and contained no quail feeders. Mean monthly survival rates were similar for most months, however, monthly survival rates did differ during February (Z = -1.66, P = 0.0485). Annual survival on the control area was 17.9% and 21.0% on the feeder area. Annual survival pooled over areas was 19.8%. Avian predation (36.9% control, 44.1% feeder) was the highest cause of mortality on both treatments, followed by mammalian predation (28.3% control, 22.9% feeder), and hunting (14.1% control, 15.5% feeder). Most cause-specific mortality was similar between treatments area during the 5 year study period. However, avian predation was higher (Z = -2.22, P = 0.0132) on the feeder area. Mean bobwhite density was similar (t = -1.07, P = 0.2919) between the feeder (0.44 birds\acre) and control (0.31 birds\acre)areas. Density differed (F = 2.67, P = 0.0299) among years and between seasons (F = 20.601 P = 0.0001). Mean covey size was similar (t = 0.191 P = 0.8525) between the feeder (10.2 birds\covey) and control (10.5 birds\covey) areas. Mean covey size was similar (F = 1.301 P = 0.2798) among years, but differed (F = 40.56, P = 0.0001) between seasons. Mammalian mean monthly visitation rates were similar (P > 0.2660) between areas. Mean monthly visitation rates were not correlated (P > 0.2505) with estimated crude mean monthly bobwhite mortality caused by mammals. Incidental sighting of accipiter hawks was higher (P = 0.0387) on the feeder area. Sightings of buteos and northern harriers (Circus cyaneus) were similar (P > 0.2730) between areas. Mean monthly sightings of all avian predators pooled and northern harriers were strongly correlated (r = 0.74, P = 0.0001) to avian cause-specific mortality of bobwhites. During the 1992 through 1996 nesting seasons we monitored 211 bobwhite nests. The average clutch size was 14.2 eggs (SE = 0.3) .We have also documented polygamous behavior during the breeding season. Of the birds alive on April 1 each year (223 females and 289 males) 37.7% of females and 9.3% of males successfully hatched >1 nest. Nesting females that survived the nesting period incubated an average of 1.5 nests and suriving males incubated just over 1 nest. Of the females that were successful on their initial nesting attempt, 24.3% attempted second nests. Female first nests represented 56.6%, female renests 13.3%, female double-clutch attempts 6.2%, and male-incubated nests 23.9% of all nests located. Chicks hatched in only about half of the nests, the remainder of the nests were destroyed by predators (mainly snakes) .The average brood-rearing period was 39 days (SE = 4.1 days) .The estimate of chick survival pooled over years and sex of the parent from hatching to 39 days was 37%, most dying within the first 3 weeks. Male bobwhites raise 5 to 35 percent of the broods. Adult bobwhites will adopt and/or abandon chicks within broods as nearly 17% of the broods eventually had more chicks than were hatched from the nest.