Impact of reproductive effort on survival of Rio Grande wild turkey hens in Texas
Authors: B. A. Collier, K. B. Melton, J. B. Hardin, N. J. Silvy, M. J. Peterson
The southeastern portion of the Edwards Plateau of Texas, historically a stronghold of Rio Grande wild turkeys Meleagris gallopavo intermedia, has seen the numbers of turkeys declining since the 1970s. Because hen survival is a key parameter affecting turkey population dynamics, we monitored radio-tagged Rio Grande wild turkey hens on the Edwards Plateau during 2001-2007 to compare survival during the breeding season in areas where turkey abundance has declined vs areas with stable populations. Breeding season survival was best predicted by a model that allowed variation during different periods of the reproductive season (initial nesting during 25 March - 21 April, renesting during 22 April - 12 June and post-nesting during 13 June - 2 July) and differences between stable and declining regions. Model-averaged estimates of breeding season survival were higher in the stable region (0.88; 95% CI: 0.78-0.94) than in the declining region (0.67; 95% CI: 0.55-0.78). Data collected on nests and hens during the intensive monitoring part of the study conducted during 2005-2007 indicated that breeding season survival was negatively affected by the amount of reproductive effort each season, i.e. the number of days a hen spent incubating a nest. Breeding season (25 March - 2 July) survival (0.86) was higher for non-nesting hens than for hens that nested (0.68; average of 15 days spent nesting). Our results suggest that differences in productivity between stable and declining Rio Grande wild turkey populations in the Edwards Plateau of Texas were associated with differences in breeding season survival due to variable reproductive effort, which, when combined with precipitation-dependent boom-bust dynamics common to galliforms in this region, could limit long-term population productivity and maintenance.
Collier, B. A., K. B. Melton, J. B. Hardin, N. J. Silvy and M. J. Peterson. 2009. Impact of reproductive effort on survival of Rio Grande wild turkey hens in Texas. Wildlife Biology 15:370-379