270 Intermarriage. 



aware of, has ever been discoverecl. It is one of the 

 most prominent facts in their history. It is not for 

 warmth, because the}^ pack long before it is cold. 

 This summer I saw large flocks of starlings flying to 

 their favorite firs to roost on the evening of the 19th 

 of June. The cuckoo was singing on the 17th two 

 days before. 



It would be interesting to know, too, whether 

 birds are reall}' as free in the choice of their mates in 

 spring as at first sight appears. They return to the 

 same places, the same favorite hedge, and even the 

 same tree. Now, when the flocks split up into sec- 

 tions as the spring draws near, each section or party 

 seems to revisit the hedge from which the}" departed 

 last autumn. Do they, then, intermarry year after 

 year? and is that the reason why they return to the 

 same locality? The fact of a pair building by chance 

 in a certain hedge is hardly enough to account for 

 the yearly return of birds to the spot. It seems more 

 like the return of a tribe or gens to its own special 

 locality. The members of such a gens must in that 

 case be closelj^ related. As it is not possible to 

 identify individual birds, the difficulty of arriving at 

 a clear understanding is great. 



Why, again, do not robins pack? Wh^^ do not 

 blackbirds, and thrushes, go in flocks? They never 

 merge their individuality all the year round. Even 

 herons, though they fish separatel}^, are gregarious 

 in building, and also often in a sense pack during 

 the day, standing together on a spit or sandbank. 

 Rooks, starlings, wood-pigeons, fieldfares, and red- 

 wings, mav be seen in winter all feeding in the same 

 field, and all in large flocks. 



