CHAPTER IX 



A caterpillar year Its effect on birds Pied Flycatchers Nesting boxes 

 Increase and death-rate amongst birds Changes in fauna Plumage of 

 Flycatchers " Spinners." 



THE increase in the supply of food, which "a Caterpillar 

 Year " affords, must lend a flavour of tropical indolence to 

 the lives of all such creatures as eat them. To make a 

 living in such circumstances can be little more than what 

 a Yankee might describe as " quite a cinch." Upon the 

 occasion referred to in the last chapter, a common Shrew 

 was noticed feeding upon one, and nearly all the Wasps 

 returning to their nest on a wayside bank were laden with 

 small caterpillars, or parts of them. Jackdaws and Rooks 

 were conspicuously engaged in collecting them amongst the 

 oak branches, and a Thrush was supplying the wants of a 

 half-fledged family of six with Hybernia larvae, picked from 

 a branch quite close to her nest. Six is such an unusually 

 large clutch for a Song Thrush, as to be suggestive of the 

 influence of food on fertility ; but unless Campbell's dictum, 

 that coming events cast their shadows before, were to be 

 applied, that explanation can hardly be accepted here ; for, at 

 the time the eggs were laid, there could scarcely have been 

 any indication of the present redundance of supplies. Wood- 

 and Willow - Warblers, Blackcaps, Spotted Flycatchers, 

 and Tree Pipits are all abundant here ; and amongst other 

 birds noticed feeding freely on the caterpillars, on this and 

 subsequent occasions, were Greenfinches, a Sparrow, a Red- 

 backed Shrike, Yellowhammers, Chaffinches, a Jay, a Dipper 

 (where they had fallen into the stream), and Pied Flycatchers. 

 The latter were perhaps as assiduous in their attentions to 

 the larvae as any other bird. Time after time I watched 

 them catching caterpillars that hung suspended in mid-air 



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