Northern Bobwhite Reproduction in the Rolling Plains of Texas

Abstract: Bobwhites have declined across their range in the past few decades. Much research has gone into slowing, stopping, and reversing this decline. Broadcast supplemental feed is a technique that has worked in the southeast to bolster bobwhite populations. When first tested in the Rolling Plains, broadcast feeding had a positive impact on nesting and annual survival. My goals were to determine if reducing the amount of feed provided similar benefits. We used three treatments, full feed (~69.1 kg/km), half feed (~34.6 kg/km), and control (no feed) using milo on two separate pastures on the Four Sixes Ranch in Guthrie, TX. I evaluated nest survival in Program MARK using the nest survival model. To evaluate bobwhite reproduction I radiomarked 350 bobwhite hens during October 2013 – March 2014 and October 2014 - March 2015. The top models for nest survival were quadratic time, quadratic time + attempt, and quadratic time + treatment. The quadratic time variable was determined to be the most important and carried 51% of the model weight. The remaining two variables, attempt and treatment carried 21% and 20% of the model weight respectively. Nest site selection was not influenced by feeding treatment. Brood success was not affected by feeding treatment. Clutch size was influenced by feeding treatment in 2014 with the full feed treatment having larger clutch sizes than half feed or control treatments. This was the fourth year of supplemental feed data that indicated there was no influence of supplemental feed on nest success, but that broadcast supplemental feed could potentially increase nesting season length and increase clutch size. Additionally, we evaluated nest vegetation, and temperature and their influences on nest survival. We evaluated 214 nests for vegetation characteristics based on nesting substrate and vegetation height. We found that the overall habitat patch associated with a nest had an impact on nest survival. Specifically a nest that was located in a habitat patch of at least 42 cm of height had a greater chance of survival then a nest located in a shorter habitat patch. In areas where that was not available increased visual obstruction at the nest improved nest survival. No nest evaluated for temperature approached a lethal threshold during this study and nests closely matched the temperature of the incubating hen.