INTRODUCTION 29 



/Wood Duck Phoebe 



Woodcock Fish Crow 



iX'Tvilldeer ^Cowbird 

 **VIourning Dove Pipit 



The last few days of the month often bring no new arrivals, 

 but increasing numbers of those species already on the move. 

 By the end of the month the rarer winter visitants and those 

 which arrive last in the fall, such as the Snowflake and 

 Horned Lark, have usually completely disappeared. 



In early April the pronounced developments in the 

 vegetable and insect worlds bring our first Warblers and other 

 species largely dependent upon insects for food. They often 

 arrive in a marked "wave," which is usually between the 7th 

 and the 12th. Occasionally in very mild and advanced 

 seasons half the species of this group arrive the last days of 

 March, and the balance perhaps before April 7th. The 

 following species belong in the early April group : 



(March 25-April 12) 

 ^Pied-billed Grebe Savannah Sparrow 



Double-crested Cormorant ^xWhite-throated Sparrow 



Blue-winged Teal vX*nipping Sparrow 



wOreat Blue Heron vXField Sparrow 



Wilson's Snipe Swamp Sparrow 



Piping Plover ^Tree Swallow 



i^tlsprey ^/Yellow Palm Warbler 



U^apsucker Pine Warbler 



iXYesper Sparrow wRuby-crowned Kinglet 



Hermit Thrush 



The balance of the month is the most difficult period of 

 the spring migration to describe, as it often breaks the rule 

 that as the season advances more species arrive in proportion 

 over a given space of time. Between the 17th and the 25th 

 the following species appear, but I have never known them 

 to appear together. At the same time the numbers of the 

 early April migrants are greatly increased, and the migration 

 of the fresh-water ducks is concluded. 



