parison of the average temperature and cloudiness, as reflected 

 by the total precipitation, in the two winters might help to explain 

 the 19-day delay in hatching in 1951. Presumably, the three 

 months before the normal onset of breeding activity would afiFect 

 this phenomenon. In 1950, the temperature was 1.3 degrees above 

 normal for this period and the precipitation was 2.02 inches below 

 normal (normal is 4.37). In 1951, the temperature was 2.7 degrees 

 below normal and the precipitation was 0.82 inches above normal for 

 the same period. Thus, the combination of light and temperature 

 was presumably less in 1951. While a study over a much longer 

 period of time, employing more refined techniques for measuring 

 the amount of Hght, would be necessary to justify drawing any 

 definite conclusions, these data do indicate that the winter weather 

 in 1951 might have delayed the onset of breeding. 



Y 



151 



• • • • • 



I ' ' I I I I I I I I'll 



10 20 30 40 50 60 70 



AGE IN DAYS 



Fig. 8. Scatter diagram of size of brood seen (Y axis) plotted 

 against estimated age of brood in days (X axis) and regression line 

 of Y on X. r = —.091. Data are from the Welda Area, 1951. 



The smaller size of the broods observed in 1951 probably was a 

 result of the unusually heavy precipitation. Schwartz (1945:67) 

 called attention to the destructive eflFects of heavy rain in the hatch- 

 ing period. In 1951, the average size of clutches in successful nests 

 was 12 eggs; nevertheless at the time when the chicks were able 

 to fly, approximately ten days of age, the average brood contained 

 less than five chicks (approximately eight in 1950). Precipitation 

 in June of 1951 was 12.04 inches at Gamett. This is 7.30 inches 

 above normal for this part of eastern Kansas. Precipitation and 

 temperature in the same period of 1950 were near normal. 



In summary, in most years, and possibly in every year, the most 

 critical time for the greater prairie chicken in Kansas seems to be 



[30] 



