When the average number of calls per dove (Figure 5) is compared 
with the average number of calling doves, we find that individual doves 
called more frequently on those days in which relatively more doves 
were heard. Conversely, on days when relatively few doves were heard, 
there was a decrease in the average number of times individual birds 
called. Thus our data seem to indicate that there might be a correla- 
tion between the number of doves calling and the number of times each 
dove called during a particular period of the nesting season. This 
seeming correlation continues to prevail after the late June-early. July 
peaks, even though the number of calling birds declines sharply. 
Remarks.--From a statistical analysis of the 1951 data for routes 
#1, #2 and #3, during the period in which the census should be taken, 
Earl Atwood of the Fish and Wildlife Service found that 36 trips would 
be necessary to reflect a 15 percent change in any one of the routes. 
If all three routes were censused and considered as a unit only 12 
trips per route would be needed. 
Thus, the period from about May 15 to about June 26 allows for 
field studies to be completed in time to have the information avail- 
able for consideration when annual hunting regulations are being 
formulated. 
Summary 
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 de- 
pressions 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. 
filthough 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 
- central Maryland. 
33 
