1 86 BIRD BEHAVIOUR 



him from clearing the colony, which included 

 besides the rightful owners a tree-building Teal 

 (of some species) as an additional but harmless 

 parasite. 



The Sparrow, as we all know, too often evicts 

 the House-Martin and takes possession, but it is 

 not so familiar a fact that the Swift does the same 

 thing by him ; this seems not to have been recorded 

 since the days of Gilbert White, but it used to 

 happen regularly under the eaves of Mr. B. Clarke's 

 photographic studio at Maidstone when I was a 

 boy at school there with his sons. 



In Argentina the Oven-bird's cosy nest is coveted 

 by a Saffron-Finch (Sycalis felzelni) and a Tree- 

 Martin {Progne ta-perd), this powerful Swallow even 

 fighting the owners for its possession, and sometimes 

 successfully ; and, strangest of all, the Wood- 

 Sandpiper {lotanus glareola) and some allied species 

 of Sandpipers breed in old nests of other birds 

 and of squirrels. 



The remarkable phenomenon of parasitism in the 

 young of birds has been known in the case of the 

 common European Cuckoo from classical times, and 

 is quite proverbial, though even in the habits and 

 procedure of this well-known bird there are many 

 points yet to be made out ; but it occurs not only 

 in many other Cuckoos — though only in those of 

 the Old World, and not universally there — but has 

 originated independently in the Cow-birds, Pas- 

 serines belonging to the family of Troupials {Icte- 

 rida), which is intermediate between the Finches 



