336 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 19 32 



females to be less suspicious than males, which are frequently led 

 into the traps by their consorts. Nevertheless, as early as 1922, while 

 experimental work to develop a satisfactory duck trap was in prog- 

 ress a total " catch " of 388 mallards was divided into 248 males 

 and 140 females, or a ratio of a little less than two to one. Personal 

 experience since that time in other regions, at other seasons and 

 with other species has indicated a corresponding preponderance of 

 males over females. Also, the operators of other waterfowl banding 

 stations frequently have commented upon the relatively large num- 

 bers of males that were trapped in proportion to the females. 



Generally speaking, all birds are naturally monogamous, so 

 theoretically it would seem logical to assume a reasonably perfect 

 numerical equality of the sexes. This condition has been borne out 

 by investigators who have studied the sex ratio of the domestic fowl. 

 For example, Darwin worked out the ratio as 48.64 to 51.36 in favor 

 of the female, while more recently Prof. Raymond Pearl, of Johns 

 Hopkins University, working on a basis of 22,000 chicks, obtained 

 a ratio of 48.57 to 51.43 males to females, thus giving almost perfect 

 confirmation to the pioneer results of Darwin. The apparent situa- 

 tion among our waterfowl appears, therefore, to warrant serious 

 study. 



As a contribution to the subject the author has made (1932) a sta- 

 tistical anal5^sis of the banding data for certain species of ducks. 

 The material available for study consisted of banding records from 

 about 50 trapping stations located geographically from Maine, Con- 

 necticut, and South Carolina, west to California and Oregon, and 

 from Alberta, Saskatchewan, and Michigan, south to Georgia, 

 Louisiana, and Texas. The data represented 10 of the most im- 

 portant species of game waterfowl and totaled 40,904. This was only 

 a little more than half of the grand total of banded ducks, but 

 certain lots of records were considered ineligible for inclusion in the 

 study for various reasons. Among these were the unknown ability 

 of some operators to sex their birds, particularly in late summer and 

 early fall when the plumage of immature birds closely resembles 

 that of the females. In other words, all data that in any way might 

 be considered as open to question were excluded from the study. 



The proportion of sexes in the total number was 24,411 males to 

 16,493 females, or about three males for every two females. The 

 detailed comparison shown by species is well illustrated in Table 4. 



The results shown in the gross numbers are similarly borne out 

 by the records from the individual stations, in some cases the pro- 

 portion being even greater. For example, of 415 mallards banded 

 at Dawson, N. Dak., in the autumn of 1926, 309 were males and 106 

 were females, or a ratio of nearly 3 to 1. 



