J 
Vol. 19, No. 8 
Page 4 
By contrast, during the last 8 years from 1969 through 1 976 , 33 cases 
(6.7 percent) of nest desertion were noted among a sample of 496 prairie 
chicken nests. This period coincides with the period of (1) increasing 
numbers of pheasants, ( 2 ) pheasants commonly nesting, ( 3 ) increasing 
parasitism of prairie chicken nests by pheasants, and ( 4 ) observations of 
interspecific harassment on the sanctuaries. In two cases where prairie 
chicken nests were parasitized by pheasants, the eggs of both species were 
intact and deserted in one nest, whereas in the other nest 12 prairie 
chicken eggs were intact and deserted but 5 of 7 pheasant eggs were hatched. 
Thus, the failure of the two prairie chicken nests was clearly related to 
interference by pheasants. 
The causes of desertion were less certain for the remaining 31 nests. 
However, pheasant nests or parasitized prairie chicken nests were found within 
402 meters (1/4 mile) of 19 (61 percent) of these 31 deserted nests. Also, 
pheasants were commonly seen or heard crowing during the breeding season in 
the vicinity of 26 (84 percent) of the 31 abandoned nests. Thus, although 
proof is lacking, there is reasonable evidence to suspect that pheasants are 
causing a high percentage of the abandonment of prairie chicken nests on the 
Bogota Study Area. Nest desertion and parasitism due to pheasants (MWRL 19 
(3) :3) are thus coinciding with high levels of nest predation by mammals 
(MWRL 19(7):3) to severely limit reproductive success and thereby depress 
population levels of prairie chickens at Bogota during the past 4 years. 
