18 



THE BIRD-LIFE OF A YEAR. 



Birds Nesting. 

 (In addition to the species which began to nest in March, all of 

 which will have eggs or young in April, the following may be 

 found nesting) : 



Nut. 



Mat. 



As the season advances, marked changes in tem- 

 peratui^e are less likely to occur, and the migration 

 becomes more regular and continuous. In Febru- 

 ary and March there may be two weeks or more 

 variation in the times of arrival of the same species 

 in different years ; in May we can expect to find a 

 given species within a day or two of a certain date. 

 Nevertheless, we shall find the force of the migra- 

 tory current still closely dependent on meteorologic 



* Transient Visitant passing further north. 



