NIDIFICA TION 633 



species brooks not the society of aught but its mate. Birds there 

 are of eminently social predilections. In Europe, excepting Sea- 

 fowls — whose congregations are universal and known to all — we 

 have perhaps but the Herons, the Fieldfare, and the Rook, which 

 habitually flock during the breeding-season ; but in other parts of 

 the world many birds unite in company at that time, and in none 

 possibly is this habit so strongly developed as in the Anis of the 

 Neotropical Region, the Republican Swallow of North America, 

 and the Sociable Grosbeak (Weaver-bird) of South Africa, which 

 last joins nest to nest until the tree is said to break down under 

 the accumulated weight of the common edifice.^ 



In the strongest contrast to these amiable qualities is the para- 

 sitic nature of the CucKOWS of the Old World and the Cow-BIRDS 

 of the New, but this peculiarity of theirs has been already dwelt 

 upon. Enough to say here that the egg of the parasite is introduced 

 into the nest of the dupe, and after the necessary incubation by the 

 fond fool of a foster-mother the interloper successfully counterfeits 

 the heirs, who perish miserably, victims of his superior strength. 

 The whole process has been often watched, but the reflective 

 naturalist will pause to ask how such a state of things came about, 

 and there is not much to satisfy his enquiry. Certain it is that 

 some birds whether by mistake or stupidity do not un frequently 

 lay their eggs in the nests of others. It is within the knowledge 

 of many that Pheasants' eggs and Partridges' eggs are often laid 

 in the same nest, and it is within the knowledge of the writer that 

 Gulls' eggs have been found in the nests of EiDER-Ducks, and vice 

 versa ; that a Redstart and a Pied Flycatcher, or the latter and 

 a Titmouse, will lay their eggs in the same convenient hole — the 

 forest being rather deficient in such accommodation ; that an Owl 

 and a GoLDEN-EYE will resort to the same nest-box, set up by a 

 scheming woodsman for his own advantage ; and that the Starling, 

 which constantly dispossesses the Green Woodpecker, sometimes 

 discovers that the rightful heir of the domicile has to be brought 

 up by the intruding tenant. In all such cases it is not possible to 

 say which species is so constituted as to obtain the mastery ; but 

 just as it is conceivable that in the course of ages that Avhich was 



^ There are not many works on nidification, for " Caliology" or the study of 

 nests has hardly been deemed a distinct branch of ornithological study. A good 

 deal of instructive matter (not altogether free from error) will be found in E,ennie's 

 Architecture of Birds (London : 18-31), and there is Mr. Wallace's most interest- 

 ing dissertation, " A Theory of Birds' Nests," originally published in t\iQ Journal 

 of Travel and Natural History (1868, p. 73), and reprinted in his Contributions 

 to the Theory of Natural Selection {London : 1870). Andrew Murray's and the 

 Duke of Argyll's remarks on this essay are contained in the same volume of the 

 Journal named (pp. 137 and 276). The late Mr. J. G. Wood's Homes vnthout 

 Hands, perhaps the best of his books, contains a popular account of many Birds' 

 nests, but is devoid of scientific treatment and disfigured by some glaring errors. 



