Moffat. - Co/o/^/'.s of Birds. 



45 



join in would only double the damage, to the disadvantage 

 of the species. But with birds that nest in holes the 

 opposite is the case. Here the possessor of a good nesting 

 site has to fight, not merely for his area against birds of 

 his own species, but for possession of the actual hole in 

 which the nest is to be built — a possession that is sure 

 to be coveted by creatures of many species besides his 

 own, and may have to be fought for at any time, night 

 or day, with all the strength that the defenders can muster. 

 Now here is a situation where to leave things to the cock- 

 bird would be practical suicide. When the enemy may 

 be of any species, it is certain that the species which leaves 

 the fighting to one sex will be beaten all along the line by 

 some other species in which both sexes join in the attack. 

 And so I think we shall find, in the cases of birds that 

 nest in holes, that the hen is generally as good and determined 

 a fighter as the cock, and that her bright plumage, being 

 generally the same as his, makes a joint advertisement 

 from both to all and sundry that the hole in which their 

 nest is situated will be well defended against raiding foes 

 of all kinds. 



On the same principle, too, birds that nest in communities 

 generally have cock and hen similarly coloured. Here the 

 object of the birds in associating together is to be able to 

 present their united strength in defence of the general 

 interest against a common foe. As familiar instances we 

 have the Rook, the Swallow, the Heron, and the various 

 Gulls and Terns. In all, the sexes are coloured precisely 

 alike. I believe the reason for this to be that the hen 

 birds take as good a part as their husbands in the defensive 

 wars that have, every now and then, to be waged. A 

 common uniform makes the strength of the army more 

 visible and imposing. 



I may venture here to repeat a little story which I 

 told in a former lecture to this Club, seventeen years ago, 

 about how a pair of Sparrow^s totally failed to establish 

 themselves as a nesting species in a certain farm-yard in 

 Co. Wexford by reason of the animosity they excited 

 against themselves in the birds already settled there. 

 They went first to a part of the yard where four pairs of 



