Viability of Northern Bobwhite Populations

Abstract

Quail populations are declining in North America. Hence, we modeled the viability of northern bobwhite (Colinus virginianus) populations subject to weather catastrophes and harvest to help focus management and research efforts to reverse the decline. We examined northern-latitude (winter weather catastrophes) and southern-latitude (summer weather catastrophes) populations separately, because winter survival is lower and density-dependent production is stronger in northern- than in southern-latitude populations. Under a criterion of quasiextinction at ≤14 birds (1 covey), the demographic capacity required for at least a 95% probability of persistence for 100 years was about 100 birds with summer weather catastrophes, about 500 birds with winter weather catastrophes, and about 800 birds with both winter and summer weather catastrophes. Given assumptions underlying the model, populations subject to summer weather catastrophes were sustainable under a ≤30% harvest rate if demographic capacity in autumn was about 700 birds. Populations subject to winter weather catastrophes could persist at ≤40% harvest rates and a demographic capacity of about 400 birds. Northern populations were more vulnerable to extinction in the absence of harvest, whereas southern populations were more vulnerable to extinction in the presence of harvest.