BRITISH WARBLERS 



of experiments by placing a leaf in the nest in order to see in 

 what manner the parents would adapt themselves to the 

 unusual conditions thus presented ; whether, as in the case 

 of the Whitethroat, they would treat it as if it were fasces 

 ejected by the young, or whether they would recognise the 

 nature of the obstruction. On the whole, there is little differ- 

 ence between the behaviour of the two species. I have never 

 seen a Eeed Warbler actually swallow a leaf, but its efforts to 

 do so are equally as pronounced as those of the "Whitethroat, 

 and its failure may be due to physical reasons. The leaf is 

 picked up and held in the bill, while at the same time the 

 movements necessary for swallowing are performed; it is 

 then perhaps dropped, but again picked up and finally carried 

 away. When a number of leaves are placed in the nest at the 

 same time, those that slip in between the young and are 

 pushed to the bottom are allowed to remain. If a leaf of 

 the same size as the interior of the nest is placed over the 

 young, thus completely hiding them, the female on her return 

 takes little notice. There is a slight examination and slight 

 bewilderment, but nothing more ; then she settles down upon 

 the nest and attempts to brood in the usual manner. How- 

 ever, the discomfort, and perhaps the feeling that her legs and 

 feet are not in their proper position and her feathers not 

 satisfactorily covering her young seem to make her restless, 

 and in her struggles to put matters right the leaf is soon 

 pushed over the edge. 



Incidents sometimes occur of so little importance in them- 

 selves that they may almost seem to savour of triviality, but 

 whenever they are in the nature of a check to the normal 

 routine of activities, whenever, that is to say, adaptation to 

 unusual circumstances is required, then such incidents in 

 themselves may be said to constitute an experiment, the result 

 of which is of relatively equal value in enabling us to judge of 

 the mentality of the actor as the result of an experiment 

 planned and carried out by the human mind. I can recall 

 two such incidents, both of which occurred while food was 



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