78 HOW TO STUDY BIRDS 



fly directly across the Gulf of Mexico to Louisiana, 

 Mississippi, Alabama, Georgia, or northern Florida, 

 without a single opportunity to rest. Many of them 

 are feeble fliers, and during unfavorable weather the 

 loss of life must be appalling. 



From the Gulf States the time required to migrate 

 to the latitude of New England, according to abun- 

 dant data secured by the Bureau of Biological Sur- 

 vey, seems to be ordinarily just about one month. 

 Some species move more slowly and take about six 

 weeks, while a few do it In half that time. These 

 estimates are based upon the average progress of a 

 species as a whole, and not on what a lively individual 

 might do. The dates of arrival which I shall men- 

 tion are for the latitude of New York City and south- 

 ern New England. From these, according to the 

 rate of progress as above, one can approximate the 

 time for arrival In other localities. 



The migratory movement begins before there Is 

 much sign of real spring. In some years by the last 

 week In February, if there should be a mild spell and 

 thaw, the first early spring birds suddenly appear. 

 Our hardy quartette are the bluebird, robin, red- 

 winged blackbird, and song sparrow. Each of these 

 is occasionally seen throughout the winter. About 

 the tenth of March, though, is more usually their 

 time of arrival. Should the weather continue cold 

 and stormy up to that time, and then a decided warm 

 wave ensue, these birds will arrive almost en masse, 

 and simultaneously with them some that are usually 



