56 THE CROW FAMILY 



Darwin explains the existence during the breeding season of so 

 many unpaired birds by (1) the death of one of a pair; (2) the 

 desertion of a barren mate ; (3) the assumption that " certain males 

 and females do not succeed during the proper season in exciting each 

 other's love, and consequently do not pair." The first two reasons do 

 not by themselves account for the large number available. To the 

 third, Darwin's own example of the starlings provides an objection. 

 Here, as in the other cases, there was a reserve of both sexes to draw 

 from. As the original pair of starlings were shot, and as the destruc- 

 tion of their successors was not confined to one sex, it is clear that 

 the reserve birds were pairing among themselves. Now if they were 

 prepared to pair after the death of the couple in possession, why not 

 before ? Mr. C. B. Moffat, in drawing attention to this objection to 

 Darwin's argument, suggests as an alternative reason for the number 

 of unpaired individuals the habit birds have of parcelling out the 

 ground into nesting areas. If we grant that there are not enough of 

 these to go round, then a number of pairs would have, he argues, to 

 remain unfruitful. Other objections apart, it is obvious that in the 

 case at least of persecuted species like the crow, jay, and magpie, we 

 cannot grant the premise, for here the nesting areas are considerably 

 in excess of the pairs. In the absence of more detailed evidence, it 

 is difficult to suggest any explanation. To begin with, it would be 

 very desirable to know in what proportion of cases the new mates are 

 needed only to help in incubating eggs or feeding young already in 

 the nest, and how often, in such cases, they are immature or sterile 

 birds. 1 



It will have been noted that the nuptial ceremonies of jays and 

 magpies are accompanied by " manifestations phone tiques," more or less 

 harmonious. Naumann describes the song of the magpie as a kind of 

 chattering with whistling notes intermixed, and he observes that it is 

 heard in the spring, both when the birds are in pairs and when several 

 males are courting one female. It has also been heard to sing in 



1 C. B. Moffat, Irish Naturalist, 1903, p. 158. 



