Investigations of methods of determining abundance of breeding mourning doves in certain eastern states

Abstract

A call count over a 20 mile route (beginning 1/2 hour before local official sunrise and with 20 stops of 3 minutes duration 1 mile apart) gives a more practical index to the abundance of mourning doves in the breeding season than roadside counts and area population studies tried in 1950. Calling activities showed relatively high peaks and low depressions during April and May of 1951, with a plateau in June; a decline in calling was noted after July 3, and continued until September 11, when activity apparently ceased. Although there seems to be a direct correlation between the total number of doves heard and the total number of calls recorded, available evidence indicates that the breeding index should still be based on the number of doves heard. In general, more doves were heard calling than were seen up to about mid-July, 1951, after which time doves became conspicuous and relatively few were heard; and there was an increase in doves seen from July through September with a noticeable decline in October in cental Maryland. Very little difference was noted between morning and evening roadside counts from the end of July through October, although one route indicated that morning was more favorable. Our data probably are too meager to determine if any significant difference exists. A statistical analysis of calling counts covering the period from May 15-June 26, 1951 indicates that with 3 routes, 12 trips per route must be made in order to reflect a 15 percent change. Calling counts should begin in this area (central Maryland and northeastern Virginia) no later than May 15, and the counts must be completed by the end of the third week in June to conform to the present schedule of formulating hunting regulations.