Tests of an additive harvest mortality model for northern bobwhite Colinus virginianus harvest management in Texas, USA

Abstract

We evaluated the application of using an additive harvest mortality model (AHMM) as a harvest management strategy for northern bobwhites Colinus virginianus during the 2007/08 and 2008/09 hunting seasons in two ecoregions of Texas: the Rolling Plains (RP) and the South Texas Plains (STP). We collected field data on three study sites/ecoregion (of 400‐1,900 ha each; two treatment and one control) to estimate four demographic parameters (i.e. fall and spring density, overwinter survival in the absence of hunting and harvest rate). We used these data to parameterize an AHMM (a theoretical component of sustained‐yield harvest; SYH) for bobwhites and compare model‐based predictions of spring bobwhite populations with field estimates. Our goal was to compare predictions from the AHMM to field estimates of spring density based on known rates of harvest. Compared to field estimates, the AHMM consistently underestimated spring population density (mean % ± SE) by 55.7 ± 17.8% (2007/08) and 34.1 ± 4.9% (2008/09) in the RP and by 26.4 ± 25.3% (2007/08) and 49.1 ± 2.1% (2008/09) in the STP. Prescribing a fall bobwhite harvest to achieve a specific, target spring density may be difficult given the wide variation in the model parameters (i.e. fall and spring density, and natural mortality) that we observed.