GREATER PRAIRIE CHICKEN" 251 



were killed and the eggs destroyed, presumably by coyotes, as the 

 tracks of the animals were found in the sandy soil around the nests, 

 and the mass of feathers left behind seemed to indicate the work 

 of such animals. One incubating prairie chicken was killed by a 

 horned owl; the eggs of another located in an open situation were 

 destroyed by crows, and in two other cases the eggs disappeared 

 without a trace of the intruder. One nest was accidently destroyed 

 by a farmer while plowing, and the eggs of two others were de- 

 serted where it was problematical whether the incubating birds were 

 taken by some predacious bird or mammal or were merely frightened 

 away in some manner. 



During the summer of 1930, 28 prairie chicken nests were found, 

 of which 17 reached the period of hatching and the others failed 

 for one reason or another. Indirect evidence indicates that crows 

 were responsible for the destruction of three nests of eggs. One was 

 probably broken up by a dog, four were drowned out by floods, in 

 one case the bird was killed, presumably by a mink, within a few 

 feet of the nest, in another case the embryos in the eggs were killed 

 by exposure to the heat of the sun, and one nest was deserted. Com- 

 bining the records of ,L929 and 1930, we have 40 nests of which 3 

 hatched in 1929 and 17 in 1930, 20 in all, or an average of 50 per cent 

 for all the nests observed. 



Every egg hatched of the three nests that reached the stage of 

 hatching in 1929. The 17 nests that succeeded in reaching the hatch- 

 ing stage in 1930 contained 208 eggs. Twenty -nine eggs, or approxi- 

 mately 14 per cent, failed to hatch. Only 8 of the 17 birds suc- 

 ceeded in hatching every egg, and in 9 nests there were one or more 

 sterile eggs, eggs with dead embryos, or both. Of 29 eggs that failed 

 to hatch, 6 were sterile and 23 contained dead embryos. The lat- 

 ter were killed by excessive heat of the sun or by failure of the eggs 

 to hatch in time before the old bird left the nest with her young. 



During the summers of 1929 and 1930, the date of hatching was 

 noted for 23 sets of eggs in the field or by special incubation. Of 

 these, 3 hatched in May, 17 in June, and 3 in July. The earliest date 

 of which we have a record was May 29, 1930, and the latest July 7, 

 1929. Nest No. 12 contained eggs on July 15, 1929, but it was not 

 possible to record its hatching. The average date of hatching of 

 the 23 nests was June 10. These records indicate that the majority 

 of the nests hatch during the first two weeks of June. The condi- 

 tion of the weather at this time is a most important factor in the 

 determination of the number of birds to be expected the following 

 season. A long continuous cold rainy spell with cloud-bursts, such as 

 is sometimes experienced in the Middle West during the first part 

 of June, is certain to have a disastrous effect on the broods of young 

 birds. 



