Mourning Dove Nesting: Seasonal Patterns and Effects of September Hunting
A nationwide State/Federal cooperative study was initiated in 1978 to examine effects of September hunting on mourning dove (Zenaida macroura) nesting. This study was designed to (1) determine the proportion of the annual total of dove nesting activity and production that occurs in September and October, and (2) determine if survival rates of mourning dove eggs and nestlings are lower in areas where early September dove hunting is permitted compared to areas where it is prohibited. During 1979 and 1980, 6,950 active nests were followed to obtain data on nesting patterns. Nest initiation was estimated both by backdating from hatch dates and by the numbers of nests found for the first time. The nationwide percent of the annual total of nests that were initiated in September and October was 1.0% based on backdating hatch dates and 2.7% based on nests found for the first time. Nesting activity was measured by numbers of eggs and nestlings present in weekly counts. Nationally, 4.5% of the annual total of nesting activity occurred in September and October. The observed period when 80% of the nests were active, based on hatch dates, lasted from April 22 to September 4. The measure of production used in this study was numbers of young fledged. Nationally, 10.3% of all observed fledging occurred in September and October. A decline in nests found in the latter half of the nesting season preceded the September 1 start of hunting. From this we concluded that the reduction in nesting activity at the end of the season is a natural phenomenon and not caused by hunting disturbance. In a separate part of this study, we estimated survival rates in hunted and nonhunted sections from data on 668 nests. The estimated daily survival rates for individual eggs and nestlings were 95.8% in the nonhunted and 95.0% in the hunted sections; the corresponding fledging rates were 33% and 26%, respectively. The fledging rates are lower because they are the daily survival rates operating over a 26-day nesting period. Neither differences in survival nor fledging rates between nonhunted and hunted sections were found to be statistically significant (p> 0.05). We determined that the statistical test was powerful enough to detect a reduction due to hunting from a hypothetical 96.0% to 94.2% in daily nestling survival rates (from 35% to 21% fledging rates) with 80% probability. An undetected reduction in fledging rate of that magnitude would probably reduce the overall fledging rate by less than 1 percentage point, because only a small proportion of the nesting doves is exposed to hunting for the full 26 day nesting cycle. In conclusion, we found that only a small proportion of total annual nesting attempts was exposed to hunting. There was no statistically significant difference in survival rates in sections where hunting was permitted compared to sections where it was prohibited. We concluded from this study that dove hunting under current regulations has no substantial effect on recruitment of fledglings into the mourning dove population.