Evaluating the Efficacy of Brood Flush Counts: A Case Study in Two Quail Species

• Published in: Western North American naturalist Vol. 76; no. 4; pp. 485 - 492
• Main Authors: Orange, Jeremy P., Davis, Craig A., Elmore, R. Dwayne, Tanner, Evan P., Fuhlendorf, Samuel D., Thacker, Eric T.
• Format: Journal Article
• Language: English
• Published: Provo Brigham Young University 01.12.2016; Western North American Naturalist
• Subjects: Analytical estimating; Animal behavior; Bobwhites; Callipepla squamata; Case studies; Chicks; Colinus virginianus; Environmental aspects; Estimation bias; Estimation methods; Grouse; Quails; Studies; Telemetry; Transmitters; Wildlife conservation; Wildlife management; United States > US; Oklahoma
• ISSN: 1527-0904; 1944-8341
• DOI: 10.3398/064.076.0409

Taking brood flush counts is a common sampling method that has been used for decades to estimate brood and chick survival in many gallinaceous bird species. However, brood survival estimates based upon flush counts may be biased because of low detection probabilities, occurrence of brood amalgamations, brood abandonment, and brooding adult mortality. Given that brood flush counts are still commonly used to estimate brood survival, and in some cases extrapolated to provide an estimate of chick survival, it is important to evaluate biases associated with this method. Therefore, we evaluated the use of brood flush counts to estimate brood survival of 2 gallinaceous birds: Northern Bobwhite (Colinus virginianus) and Scaled Quail (Callipepla squamata). To gain a better understanding of some of the mechanisms that may bias brood survival estimates, we radio-tagged Northern Bobwhite and Scaled Quail chicks (8–12 days old) and juveniles (4–6 weeks old) in 67 broods. We used radio-tagged chicks and juveniles to estimate and compare brood survival using 2 analysis methodologies. These methods included a telemetry method that relied upon radio-tagged chicks and a flush method that mimicked a brood flush count. In bobwhites, the brood survival estimates were higher with the telemetry-based estimate than with the flush estimate for both the 3-week chick (0.808 vs. 0.500) and 5-week juvenile (0.636 vs. 0.364). In Scaled Quail, the 2 brood survival estimates were similar at the chick (0.842 vs. 0.789) and juvenile (0.818 vs. 0.818) life stages. Because Scaled Quail have lower occurrences of brooding adult mortality and brood abandonment, flush counts provided a more accurate estimate of brood survival for Scaled Quail than for bobwhites. In situations where brood abandonment or brooding adult mortality is common, researchers using flush counts to investigate gallinaceous brood survival should consider the impact that these mechanisms may have on survival estimates.