CHAPTER IX 



PHASES OF SOCIAL LIFE 



Gregarious birds. Curious sleeping habits. Pelicans fishing. Woodpeckers 

 and food stores. Significance of gregarious habits. 



WHILE the facts related in the previous chapters with 

 regard to the relationships of birds one to another 

 are well known, they are facts which can only be 

 verified by close and careful observation. But the most casual 

 observer needs not to be reminded that many birds are gregari- 

 ous. What advantages may accrue from this relationship, and 

 what modifications thereof have been evolved are, however, by 

 no means so obvious, and it will be the purpose of this chapter 

 to trace these, at any rate in outline. 



No better example of a gregarious bird could be found 

 than that of the Rook, which the year round herds together in 

 larger or smaller bands. The Limicoline birds afford another 

 good example. But though they commonly keep together to 

 breed in colonies, sometimes of enormous size, in many cases 

 they elect to perform their parental duties in seclusion. Herons 

 breed in colonies but are otherwise extremely solitary birds. 

 While commonly birds of gregarious habits associate in small 

 parties, they may, in the case of some species, as in Flammgoes, 

 the Rice-bird {Dolichonyx oryzivorus) and Starlings, roam in 

 huge flocks. But these numbers are never so great as in the 

 vast assemblages of birds which gather together during the 

 breeding season. This is especially true of Penguins, Alba- 

 trosses and Terns, which may number millions of birds. Among 

 land birds the only parallel is, or rather was, that afforded by 

 the Passenger Pigeon {Ectopistes migratorius). A breeding 

 colony of this species was discovered in 1876 by the naturalist 

 Brewster. It began near Petosky and extended north-east, 

 past Crooked Lake for twenty-eight miles, averaging three or 



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