Effects of Hunting and Hunting-Hour Extension on Mourning Dove Foraging and Physiology

During 1993, the Illinois Department of Natural Resources extended mourning dove (Zenaida macroura) hunting hours to increase recreational opportunities. We investigated the physiological response of doves to extended hunting hours through a combination of laboratory and field procedures. We determined that food deprivation causes corticosterone levels to increase in doves, suggesting that if doves were excluded from foraging areas by hunting pressure, a rise in corticosterone levels should be detectable. Field procedures revealed that hunting resulted in a measurable increase in corticosterone levels, although the magnitude of the observed increase probably was not biologically significant (preseason x = 1.35 ng/ml vs. hunting x = 1.87 ng/ml). We did not detect differences in corticosterone levels between traditional and extended hunting hours (P = 0.25), but did find evidence to suggest that dove foraging was affected by hunting and hunting hours. Mourning dove weights were greater preseason (x = 117.4 g) than during hunting season (x = 111.0 g), which may be partially explained by an increase in the number of empty crops during hunting season (54.1% hunting season vs. 25.8% preseason). The absence of food in crops most likely accounted for the observed weight loss. Furthermore, sunflower seeds (the dove attractant) were more frequently found in crops preseason (45.1%) than after the start of hunting (22.1%), suggesting that doves hunted during traditional hunting hours foraged on sunflower seeds more than doves harvested during extended hunting hours. However, the effects of hunting on foraging did not cause rises of corticosterone levels comparable to those observed in food deprivation experiments. We conclude that most doves were not stressed by the hunting-hour change.