1917-] Breeding -habits of the Cuckoo. 215 



May and the 5tli of August, 1891. But the type of these 

 eggs does not appear to have been a distinctive one, and is 

 described by him as a mixture between Motacilla and Sylvia, 

 ■with a dull greeaish-yellow ground-colour, and markings of 

 greyish-brown over the whole surface, and a wide zone round 

 the larger end ; and as both the weight and measurements 

 varied to some exteut, they may have been laid by two 

 females, or a mother and a daughter. Indeed, the general 

 evidence as to the number of eggs laid yearly and the 

 intervening periods seems to me very slight. 



Dr. Rey concludes that many eggs get destroyed, and 

 quotes instances of having found broken shells under nests 

 or eggs built into the lining of nests. It is also stated 

 that, in the case of the Cow-birds, many eggs do not hatch, 

 some being placed in deserted nests, others in nests not 

 laid in — which are consequently abandoned, while some are 

 even dropped on the ground by the female, which appears 

 to be even more careless than the Cuckoo. 



We also know that among such kinds of domestic fowls 

 as do not incubate their eggs, the tendency is to lay a fur 

 greater number. 



Further investigation is much needed and might be most 

 successfully carried out where the Cuckoo is scarce and only 

 one or two females are found ; but unfortunately this 

 usually occurs in wild expanses where the Meadow-Pipit is 

 numerous, and it is almost impossible to find all the nests 

 of this latter species. 



From my own observations in districts where the Cuckoo 

 was both very numerous, and also limited to one or two 

 pairs, the number of eggs and young found have never led 

 me to suppose that more than nine or ten eggs were laid 

 annually, even allowing for a good percentage of breakages 

 and eggs not discovered, and I doubt if the number of eggs 

 destroyed is as large as Dr. Rey supposes. 



Also, the evidence seems to me to indicate that the eggs 

 are laid at irregular and varying intervals. The Cuckoo is 

 believed to be polygamous, and hence the laying of eggs 

 may depend on the presence of the males. With tiie Cow- 



