THE THRUSH GENUS 389 



rendered no doubt all the easier of application because the victims 

 were the offspring of another. 1 An example of inverted Squeerism ! 



A fact which has been made prominent by the photographer- 

 naturalists is the constancy with which birds tend to repeat certain 

 temporary activities. It has been illustrated by the frequency with 

 which one of a pair or both will, on approaching the nest, make 

 use of the same perch. The mistle-thrush shown feeding her young 

 on Plate XIIL, always arrived on the side furthest from the photograph, 

 her mate always on the side nearest, thus always presenting his 

 back to the lens. Similar facts are given by Mr. Herrick of 

 certain American species in his Home Life of Wild Birds? 



Another fact, rediscovered by the photographer-naturalists, but 

 recorded long ago in the pages of Macgillivray's History of Birds, 

 by the indefatigable Weir, is that mistle-thrushes, blackbirds, and 

 song-thrushes, and no doubt also ring-ouzels, when removing the 

 excreta of the young from the nest almost invariably swallow them. 

 Two or three are sometimes swallowed in succession. Usually 

 the parents wait for these articles after the young have been 

 fed, and the look of attentive scrutiny then assumed has often 

 been mistaken by the uninitiated for the lingering gaze of parental 

 love and devotion. The habit of many other species is merely 

 to convey the excreta away some distance from the nest and drop 

 them. This is not difficult, as the loose viscid matter which com- 

 poses them is contained in a thin sac strong enough to be held, 

 without breaking, in the beak. It is easy to understand that birds 

 should remove the excreta so as not to foul their own nests, or, at 

 least, the interior of the nests, for some species, the greenfinch for 

 instance, occasionally leave the outside of the nest in a foul enough 

 condition. But how certain species came to acquire the habit of 

 swallowing them will be difficult to explain. Several facts bearing 

 upon the question are given by Mr. Herrick in the work above 

 quoted, including some relating to the American-robin (T. migratorius) 



1 Zoologist, 1856, p. 5261. 2 See also p. 409 (Stonechat). 



