Evaluation of survey techniques for Rio Grande wild turkey populations in the Southern Great Plains
Butler, Matthew J.
MetadataShow full item record
Most wild turkey (Meleagris gallopavo) surveys have been limited, unstandardized, and unsuccessful. My objectives were to develop and evaluate Rio Grande wild turkey (M. g. intermedia) survey techniques in the Southern Great Plains and determine if useful trends in population change are detectable. Counting wild turkeys at winter roosts is common because they congregate in specific roosts throughout winter. I compared 5 techniques for counting winter roosts and found advanced technologies such as night vision devices, thermal infrared cameras, and automated video monitoring systems were ineffective and morning counts were best. Aerial surveys have been used to estimate abundance for several wild bird species. I used inflatable turkey decoys and radio-tagged wild turkey flocks to evaluate detectability of flocks and individuals within flocks during aerial surveys. I conducted simulations to evaluate aerial surveys and examined power to detect trends. Simulations suggested fixed-wing surveys would underestimate abundance by about 10% to 15% (2.0% to 4.8% CV), but helicopter surveys would underestimate by 5.6% (4.6% CV). Power was sufficient to detect a 10% to 25% change in 4 to 5 years. Helicopter surveys can cost 6 times more than fixed-wing surveys. Many states use opportunistic poult-hen counts to index reproduction, recruitment, and density, but I found no relationship. Ground-based surveys can be improved with line transect-based distance sampling from roads. Because wild turkeys may avoid or be attracted to roads, I examined their distributional patterns around roads and found autumn midday and winter AM were the best times for road surveys. I used decoys to evaluate detectability of flocks and individuals within flocks during road surveys. I conducted simulations to evaluate road surveys and examined power to detect trends. Simulations suggested density would be underestimated by 24% during winter (11.2% CV) and by 37% during autumn (13.3% CV). Power was sufficient to detect a 10% to 25% change in 5 to 7 years during winter. Aerial surveys were better, but are expensive. Problems with road surveys include responsive movements, avoidance-attraction behaviors, and lack of representative samples. Also, fixed-wing aerial surveys for wild turkeys may be incorporated into similar midwinter waterfowl surveys. Thus, if fiscal restrains permit, managers should use fixed-wing surveys to monitor wild turkey populations in the Southern Great Plains.