IN THIS ISSUE...
- Tall Timbers Needs Your Membership
- Bahia Grass Control Project
- Thirty-fifth Anniversary Census of the Wade Tract
- Pebble Hill Fire Plots Census
- Tall Timbers History Makes a Great Gift
- Chick Survival and Late Quail Hatch
- Red Hills Awareness Initiative
Vol 6 | No 3 | December 2013
Chick survival and late quail hatch result in above average fall quail numbers
By Theron Terhune, PhD, Game Bird Program Director
Covey call counts on many properties in the Red Hills region and Albany area indicate populations are up from last year about 30% on average with some areas seeing even higher bumps than others. We attribute this uptick to both solid over-winter survival, carrying good bird numbers into the breeding season from the previous fall, and decent amounts of rainfall, which was fairly well distributed throughout the nesting season. Our new research using thermal imagery to count bobwhite chicks indicated that chick survival was good throughout the season with the exception of a short period in early July; more than 9 inches of rain occurred in 10 days with no respite of sunny days, which moderately taxed chicks on the ground during that time. Click on the following link to view a bobwhite chick brood via a FLIR thermal camera https://vimeo.com/80478365. (This video has been slowed down 25% to facilitate counting of the 12-day old chicks scattering when approached.)
In addition to good chick survival, we also observed a stellar late hatch this year. Greater than 40% of hens (Figure 1) in late-August and early-September were incubating nests and a large proportion of those successfully hatched. Many managers in the Albany and Red Hills regions corroborated this late hatch by seeing lots of young birds in September and October, which bodes well for fall recruitment.
Figure 1. Daily proportion of radio-tagged hens incubating nests during the 2013 breeding season. The red arrows in this graph indicate 3 primary peaks in nest incubation in terms of proportion of radio-tagged hens incubating nests.
Typically when good over-winter survival, good chick survival, a good late hatch, and favorable weather align in the same breeding season one would expect an increase in fall bobwhite abundance. However, looking at fall bobwhite densities on Tall Timbers (Figure 2), we did not observe the 30% increase like many other sites in the Red Hills region.
Figure 2. Autumn bobwhite density on Tall Timbers Research Station, 2007 – 2013.
We believe this is linked to high predator abundance reducing the amount of successful nesting attempts on Tall Timbers. In fact, we observed one of the lowest nest success rates (39%) ever documented at Tall Timbers this breeding season. High nest predation resulted in a very low overall brood (chick) production (see Figure 4) on Tall Timbers. Predator abundance on Tall Timbers this year was higher than our long-term average and much higher than the recommended predator index threshold (Figure 3).
Figure 3. Predator index estimated using scent stations on Tall Timbers, 2003 – 2013.
We have found that a predator index below 15% is the preferred range for optimal bobwhite production. For more information on how to implement scent stations and how to estimate the predator index click here.
During 2004 – 2006, as part of a larger research project on the effects of mammalian nest predation on northern bobwhite populations, Tall Timbers underwent an extensive trapping program to remove mammalian nest predators. However, since this time no trapping has occurred. Figure 3 demonstrates how quickly the predator population can respond when predation management ceases. In this study, we were interested in determining how changes in predator abundance influenced nesting success. Since 2006, despite higher than recommended predator indices, nesting success was relatively high (e.g., above 50%; see Figure 4).
Figure 4. Number of nests and broods per 100 hens on Tall Timbers, 2008 – 2013.
A key lesson here is that, despite high predator abundance and low nesting success, quail abundance remained above one quail per acre. This underpins the importance of sound management including maintenance of quality habitat and supplemental feeding, which are critically important to sustaining high survival of adults. When adult birds survive they can re-nest and ultimately produce young. At the same time, to maximize quail abundance, or grow a new or recovering quail population from low numbers, predator management is often necessary. In addition to high survival, this was a year of favorable weather, good chick survival, and a stellar late hatch (despite the predators) counterbalancing low nest productivity.