McClure (1941, 1942, 1943) has given a wealth of interesting 
data on the productivity of mourning doves, although Nice (1943) has 
challenged his population analyses. McClure (193) reports that 
nesting attempts averaged from 4.6 to 5.4 per pair in different 
years (1943, pe 384). He also gives 2. and 3.0 as the mean number 
of successful broods per pair during his best two years of observa~- 
tion. Multiplied by 1.82 young per successful nest, these last two 
values could mean age ratios of the order of 5.5 ~ 6. young per 
adult at the time the young leave the nest. It is impossible, of 
course, to convert such productivity data to precise age ratios 
because the nesting of mourning doves extends over a long period 
during which mortality is constantly occurring. It is difficult 
to believe, however, that age ratios of this order would shrink to 
something approaching 1.6 young per adult by September or October. 
Population dynamics 
Length of nesting season.--Some hint of the regional varia- 
tions possible in mourning dove production is found in a review of 
the nesting activity reported thus far for the various parts of the United 
States (table 46). Other Gmaller) samples reported on by Gander (1927) 
and by Grinnell, Bryant, and Storer (1918, pp. 59-596) show a nest- 
ing season in California lasting from January to December; or (more 
properly?) from December to October. This latter period more closely 
approximates the time of enlarged testes size reported for 317 Ala- 
bama birds by Pearson and Rosene (1938). It is not yet clear if 
the length of the nesting period varies with the mean number of broods 
raised by pairs that start the breeding season. Since nest building, 
laying, incubation and fledging typically cover 33 days (Pearson and 
Moore 1939), doves in the southern states could raise more broods 
than those in the northern states. There is no evidence yet available 
that they do so. 
The monthly frequencies of nesting activity in table h6 
indeed raise more questions than they perhaps answer at this time. 
What, for instance, is the meaning of the flat-type curves of nests 
found and broods fledged in Tennessee? One is tempted to infer that 
these reflect the very high average numbers of nesting attempts and 
successful broods reported by. McClure (1943); but if this is true, 
why is McClure's own activity index so different? 
On the other hand, the distribution of 319 banding dates 
in the Fish and Wildlife Service files is quite similar to that of 
the activity index set up by McClure (19,3) for Cass County, Iowa. 
One should notice in the former that 70 per cent of the young were 
“banded before August and 92 per cent before September. It seems 
likely that more instructive sets of statistics along these lines 
could be assembled by tabulating not merely recoveries in the banding 
files (as I did) but also the numbers of nestlings actually banded 
in various parts of the country. 
10h 
