The Zoologist— May, 1873. 3503 



Up to the present time no one has been able to give any ex- 

 planation of the motive for this singular habit of the cuckoo, of 

 imposing the care of her young on strangers. It has been sup- 

 posed that the cuckoo lays, at the most, eight eggs every spring, and 

 on account of their being deposited at great intervals she would be 

 unable to hatch and rear them herself. This induces another 

 question : Why does she lay her eggs at such long intervals ? 

 This also remains unexplained ! Every theory on these points 

 is replete with interest, at least in our eyes. The small size of 

 the cuckoo's eggs is very remarkable. This large bird lays an 

 egg which rarely exceeds in size that of the house sparrow. 

 Besides which, these eggs vary as- much in size and shape as in 

 colouring, though amid all the variations of colour the experienced 

 eye can readily distinguish them, but it is difficult to express 

 the difference in words. The shell is always thin, fragile, and but 

 slightly shining. The first eggs are laid in May, the last often as 

 late as July, so that they may be deposited amongst the first or the 

 second brood of other birds. 



There are but very few birds which, like the common cuckoo, 

 leave their progeny to the care of strangers ; and amongst our 

 European Avifauna only one other species, the great spotted cuckoo 

 {Cocajstes glandarius). This bird is an inhabitant of Spain, and 

 has been known to occur also in Germany : it does not, however, 

 deposit its eggs in the nests of small birds, but has been observed 

 in Africa to availitself of that of the hooded crow, and in Spain of 

 that of the magpie. The eggs of this species are much larger than 

 those of our common cuckoo, and are always similarly marked to 

 those of the birds to whose care they are entrusted. Amongst 

 foreign birds, besides the true cuckoos, there are several species 

 which, so to speak, put their young "out to nurse." 



The foster-parents of the common cuckoo behave nobly towards 

 their charge, bestowing on the intruder a care and affection equal 

 to that evinced for their own young, and rearing it with the greatest 

 care and self-sacrifice. Not only is the appetite of the foundling 

 insatiable, taxing the efforts of its foster-parents to the utmost, 

 but it grows so fast as soon to occupy the greater portion of the 

 nest, thus outstripping its foster-brothers and sisters in size ; it 

 soon disposes of these by shifting and fidgeting, until it gets them 

 one after another on its broad slioulders, and then heaving them 

 bodily out of the nest, finally remains in sole possession : then 



