THE CUCKOO AND HIS KINDRED. 125 



songless, and in nine cases out of ten is overlooked 

 altogether. I have several times remarked the 

 presence of a pair of Cuckoos in a certain locality 

 for weeks together, and I have many notes referring 

 to this species where a male and female were in 

 company. The fact is specially noticeable in open, 

 treeless districts and near the moors, where cover 

 is scarce : here half-a-dozen separate pairs of Cuc- 

 koos may be met with in the course of a morning. 



From the pairing instincts of the Cuckoo 

 we naturally pass to the bird's parasitic habits. 

 Many more or less plausible theories have been 

 propounded to explain this wonderful instinct, 

 yet we are probably as far off as ever in our 

 attempts to elucidate it. The habit may be an 

 inherited one from some ancestral form ; it may 

 have been acquired under totally different con- 

 ditions of life from those with which these parasitical 

 Cuckoos are now surrounded ; parasitism may have 

 widely prevailed among birds in earlier epochs ; so 

 that all attempts to explain it by present facts, or 

 to harmonize it with now prevailing circumstances, 

 may be futile. It may prove of interest to the 

 student to review a few of the most plausible 

 theories on the subject. First, it has been suggested 

 that the Cuckoo migrates south too early to permit 



