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PROCEEDINGS OF THE NATIONAL MUSEUM 



gonadal condition, copulation, the carrying of nesting material or 

 food by the birds, and the observation of fledglings. In estimating 

 avian breeding activity by time of year, we use as a criterion the 

 number of species found breeding. While this appears to give to 

 one nest found in December the same value as to 50 nests of the same 

 species found in June, the results obtained appear to reflect accurately 



Figure 103. — Breeding activity of birds actually recorded in the study area (dash line) and 

 probable total breeding activity for birds in northeastern Venezuela (solid line). 



the yearly fluctuation in total breeding activity. In this connection 

 we note that in Skutch's (1950, pp. 191-194) excellent report on the 

 breeding cycle of Central American birds the seasonal change in the 

 number of nests found followed with similar fidelity the number of 

 species nesting. 



In figure 103 we show the number of species recorded by the junior 

 author as breeding in the study area. Although this graph gives an 

 idea of the increased April-July breeding activity, it is obvious from 

 the truncated shape of the cmwe that we lack complete data. Especi- 

 ally do we lack May-June data, due in part to the collector's frequent 

 absences from Venezuela dming those months. The breeding species 

 curve for northeastern Venezuela is probably better represented by 

 the solid lines in figure 103, in which, for those forms recorded by 



