228 Wild Birds and their Haunts 



CUCKOO CHARACTERISTICS 



THE injuries," says an old writer, "which so 

 frequently happen to the eggs of those birds, in 

 whose nests cuckoos lay, are occasioned, as I 

 have often proved experimentally, by the sitting bird, 

 in attempting to accommodate herself to eggs of different 

 sizes. If comparatively large and small eggs are placed 

 in the same nest, some of the smaller ones are generally 

 thrown out, or rendered useless, by the hen bird, in 

 endeavouring to arrange them so that she may distribute 

 nearly an equal degree of warmth and pressure to all : 

 but the larger ones, which chiefly sustain her weight, 

 and consequently are less liable to be moved, usually 

 remain unmolested. When the eggs of birds are ex- 

 changed for others of a uniform magnitude, whether 

 larger or smaller, than their own, provided the difference 

 is not so great as to occasion them to be forsaken, no dis- 

 turbance ensues, whatever their colour may be, the 

 change either not being perceived, or totally disregarded." 

 If there be no mistake in the fact of the cuckoo's eggs 

 having been found in the nests of wrens, it may well 

 excite a question in what manner it was introduced for 

 the entrance of any of these little nests being in the 

 side, and not more than an inch or an inch and a half 

 in diameter either way, it is obviously impossible so large 

 a bird as the cuckoo could get into the nest, which is 

 barely wide enough to admit the wren herself. 



Should we reject (though we have no reason to do so) 

 the evidence of M. Montbeillard with respect to the 

 wrens, we cannot refuse to believe the accuracy of Dr. 

 Tanner, who found a cuckoo's egg in the nest of a wagtail 

 in a hole under the cave of a cottage ; though it was a 

 singular place for a wagtail to build in. Nay, even leaving 

 these doomed nests with a narrow entrance out of the 

 question, and taking the nests most usually chosen by 

 the cuckoo for her progeny, one must conclude that 

 she cannot in many instances sit upon the nest while 



