CENSUS OF NESTING BIRDS 69 



natural enemies, the birds and beasts of prey; and by the 

 weather conditions. 



The grass of the meadow is cut at about the time the young 

 Dickcissels are hatching. The mower and the horse's hoofs 

 will crush many of the nests and following the mower comes 

 the rake to scratch up the nests. This is not quite so disastrous 

 to the Meadowlarks, for many of the Meadowlarks have left 

 the nest before the grass is cut. 



The Meadowlarks and also the Dickcissels are sometimes 

 seriously disturbed by seasons of wet weather, for both these 

 species nest on the ground. This meadow is low and almost 

 swampy in rainy seasons and since the heaviest rains occur 

 about the time the Meadowlarks are hatching, in wet seasons, 

 no doubt many are drowned or chilled to death. 



Add to these menaces the constant dangers and death rate 

 during migration, and it is doubtful if there will ever be any 

 increase in the number of birds in this region from year to 

 year. Should the number increase for a time, according to 

 the rules of balance in nature, their enemies would increase in 

 proportion until the normal number of birds was again 

 reached. 



With some other species, and in some other part of the 

 Park the problem might be different. Many Chickadees were 

 found in the horseshoe bend of the Blue River in Section Num- 

 ber 10, yet more could probably find insect food in this moist 

 insect-breeding region than are there. Yet, there is not likely 

 to be any increase in numbers. In this case, the check would 

 probably be in the number of suitable nesting places, for the 

 Chickadee must depend upon natural cavities in the trees, such 



