30 



FOOD OF SOME WELL-KNOWN BIRDS. 



securely while tearing it in pieces. "V^Tienever butcher birds capture 

 prey that must be torn apart, they press it firmly down into a sharp 

 crotcli, wliere it can readily be dissected. "RTien food is abundant, 

 surplus captures are hung, until needed, on thorns, sharp twigs, 



splinters, or the 



of 



wire 



of 



.\' 



barbs 

 fences. 



Like birds 

 prey and some 

 other birds, the 

 butcher bird habit- 

 ually disgorges the 

 indigestible part of 

 its food after di- 

 gesting the nutri- 

 tive portion. The 

 bones and hair of 

 mice are rolled into 

 compact pellets in 

 the stomach before 

 being disgorged. 



For the investi- 

 gation of the food 

 of the southern 

 butcher bird 124 

 stomachs of the 

 western subspecies 

 and 88 of the east- 

 ern were examined. 

 The western birds 

 showed 2.5 per cent 

 of vegetable suIj- 

 stances in their 

 stomachs, but the 

 eastern ones con- 

 tained nothing but 

 animal matter. 

 Animal food. — 



The animal portion of the food of western butcher birds consists 

 of insects 83 per cent, spiders and a few snails 2 per cent, and 

 vertebrates 12 per cent. The stomachs of the eastern forms show 

 insects G8 per cent, spiders 4 per cent, and vertebrates 28 per cent. 

 The difference is undoubtedly due to climate, the western bird being 



506 







'if-i 





%^m- 



Fig. 14. — Southern butcher bird. 



