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Calling Rates and Monitoring

Call counts are commonly used for bobwhites during spring and fall. A raw call count provides an index to quail abundance, such as number of males heard/point or number of coveys heard per point. Even when call counts are adjusted using distance methods to account for the likelihood of hearing them call at various distances, the estimates of density are still biased low because not all quail call during a survey. Understanding what proportion of coveys or male bobwhites is likely to call during a survey would improve estimates of density which has important implications for management, research, and harvest.
As such, we conducted long-term research on covey calling by bobwhite during autumn and developed techniques to measure fall abundance. Through years of research and collaboration with others, we have developed a method to assess quail density.

Understanding calling rates of males will improve our ability to measure bobwhite populations

Understanding calling rates of males will improve our ability to measure bobwhite populations.

Spring Call Count Research

In addition to the covey calling rate studies, in 2009 we began studying the calling rate of male bobwhites to begin to develop ways to estimate population density during the breeding season from call counts. Some of the early questions we had is what proportion of males were likely to call, how consistent is the calling rate from day to day and month to month, how important is it to standardize timing of survey and finally how was calling related to reproductive status.

After 3 years of study, we have found that the calling rate of bobwhites during the months of May and June is ranges from 40 to 50% for a 5 or 10 minute call survey. The data also support that calling rate does not vary that much between sunrise and about 10am providing ample time to monitor multiple points in a morning survey.

Time of Morning and Calling Probability

Calling rates were consistent from sunrise until about 10am

 

10-Minute Listening Period

During May and June calling rates were predictable.

 

Our 2011 data collected by intern Seth Sofferin shows almost identical results to 2010. We are conducting an analyses to determine how factors affect day to day calling rates, such as weather, number of nearby calling bobwhites, reproductive status (with brood, with pair, incubating, or unpaired). Once this analysis is completed we hope to be able to adjust bobwhite call surveys for using a combination of distance sampling and calling rate models to provide an unbiased measure of density. This will allow us another tool to assess bobwhite density for both research and management, such as supporting the need for translocation of wild birds to a new property, or predicting fall populations and acceptable harvest levels.