242 WAGTAILS AND PIPITS 



at least to be sure, or in so marked a degree where the careful and 

 elaborate display of the plumage has. But this is not sufficient to 

 destroy the parallel, inasmuch as it is exactly what one might expect 

 since birds can hear, but cannot see themselves, effectively. We, 

 too, will sing for our pleasure, but only pose, alone, before a glass. 



Turning from the courting activities of the Motacillidce to those 

 which naturally succeed them, we come, at once, in the pied-wagtail 

 as also in its continental representative, M. alba to a very interesting 

 peculiarity in connection with its nesting habits, along the lines of 

 which, as I believe, the origin of the parasitic instinct in the cuckoo, 

 and one or two other birds, is to be sought. In the Zoologist for 

 November 1904, the Rev. F. C. R Jourdain drew attention to the fact 

 that M. lugnhris not infrequently adapts the nest of some other species 

 to its own needs, and gave seven authenticated instances, in- 

 cluding two that had fallen under his own observation, of 

 this peculiarity. To these, in the following number of the same 

 organ, Mr. Jourdain added two other such, in respect of the 

 same species, and one on the part of M. alba as made known by 

 H. J. Pearson in his Three Summers among the Birds of Russian Lap- 

 land. The above ten instances range from 1862 to 1904, and the 

 nests utilised were those of the swallow (once), robin (twice), and 

 blackbird and song-thrush (each three times), whilst M. alba's choice 

 had fallen on that of the fieldfare. 



In the latter case, and in seven out of the nine others, the 

 appropriated nest was an old one, but from one of these the young 

 had but just flown, whilst on two occasions it had been deserted only, 

 by the respective rightful owners robin and song-thrush. In regard 

 to these deserted nests, we are left in doubt on a very crucial point, 

 whether, namely, the owners had abandoned them before the wag- 

 tails appeared on the scene. Since, however, there are always 

 some considerable spaces of time during which a nest in course of 

 construction is left unvisited by the building birds or bird there 

 seems no reason to suppose that an egg, in some cases of this kind, 



