by Bent (1932:248) to be the product of two or more hens. The 

 maximum clutch thought to have been produced by one hen is 17 

 (see Hamerstrom, loc. cit.). The average size of 66 clutches in 

 Wisconsin was 12 (Hamerstrom 1939:113). 



Audubon (1834:494) noted that second nests had fewer eggs 

 than first nests. Hamerstrom {loc. cit.) found that there was a 

 decline in the average size of the clutch as the date on which the 

 first egg was laid was progressively later. A similar dechne in size 

 of clutch was noted in the 13 full clutches found in 1951 on the 

 Welda Area. Figure 6 shows the temporal distribution of these 

 clutches, their size and the regression line of size of clutch against 

 date of first egg laid. The regression coefficient, r = — .702, rep- 

 resents a high degree of negative correlation between the date of 

 first egg laid and the size of the clutch. 



Y 



15 



X 



u 



5,0 



-J 



O 



lU 



M 



5 



25 30 5 10 15 20 25 30 4 



APRIL MAY JUNE 



DATE OF FIRST EGG 



Fig. 6. Scatter diagram of size of clutch (Y axis) plotted against 

 estimated date on which first egg was laid (X axis) and the regres- 

 sion hne of Y on X. r = — .702. Data from the Welda Area, 1951. 



The dates on which first eggs were laid occur in three groups 

 (see Figure 6). The mean intervals between these groups are 

 16 and 17 days. This grouping suggests that re-nesting occurred 

 after failure of first nests. Hamerstrom (1939:115) found that the 

 greater prairie chicken has certain breeding characteristics in com- 

 mon with the bobwhite quail, which is known to re-nest, and con- 

 cluded from this that the prairie chicken re-nests. Lehmann (1941: 

 15) found that some Attwater prairie chickens re-nest as many 

 as two times, after failures, for a total of three nesting efforts. 



In summary, although the sample is small, it seems clear that 

 early clutches are larger, are more successful, and produce most 

 of the young. Sixty-eight of the 79 chicks that were produced from 

 16 nests came from the earUest eight nests. As Lehmann ( 1941:15) 

 says relative to the Attwater prairie chicken, "A successful season 



[28] 



