HOW THE BIRDS KNOW 341 



Long before we know, the birds are aware of the 

 approach of those sudden summer storms. While 

 fisherfolk are busy casting, hunters searching the 

 wood, and picnickers gay in the parks, the birds 

 have their warning and silently steal away to 

 shelter, so that when the first black cloud drifts 

 across the sky, and the first ominous peal of thun- 

 der rolls, we suddenly become aware of how still 

 it is, and realize that previous to our warning, the 

 little feathered folk have had theirs and are safe. 

 Whether there is a change in air currents imper- 

 ceptible to us, whether birds of high flight see the 

 storm clouds gathering, and their dropping to earth 

 warns the small folk, or how they know is their 

 secret. Any woodsman can tell you that it is 

 quite true that the birds know first. 



Slacker Cowbird knows a few things of vast 

 importance in placing the eggs which perpetuate 

 her species in the nests of other birds. She knows 

 that her eggs will hatch one day sooner than those 

 belonging in the nest in which she places them. 

 She knows that if she places them in the nests of 

 catbirds and thrushes of her size they will hatch 

 at the same time as the other eggs and her young 

 will have only an equal chance with its nestmates. 

 This does not suit the shirk of birdland, so she places 

 her eggs in the nests of birds not half her size, song 

 sparrows, indigo finches, vireos, warblers, where her 

 young will hatch first and be twice the size of the 

 other nestlings and so can lift their heads higher, 



