WESTERN YELLOW-BELLIED FLYCATCHER. 55 



THE WESTERN YELLOW-BELLIED FLYCATCHER. 



(Empidonax difficilis.) 



The western yellow-bellied flycatcher occupies the western part of 

 the United States from the Pacific coast eastward as far as the eastern 

 foothills of the Rockies and as far north as Alaska. It is found on 

 its summer range about eight months of the year and in winter in 

 Mexico. While somewhat partial to the recesses of the forests it 

 takes kindly to the open, when other conditions suit, and since the 

 advent of civilization it finds orchards quite to its mind as foraging 

 grounds. Like the Richardson's pewee it prefers a bare dead twig 

 for a perch, where it sits and watches for flying insects. Like all 

 flycatchers it has keen eyesight, for it often sees and darts at an 

 insect which is so far away as to be invisible to the human eye. 

 The nest is built in various places, but usually in a covered site. A 

 hollow tree, a bracket of a house porch, a beam under a bridge, a 

 crevice among the roots of an overturned tree or under the over- 

 hanging banks of a stream are fair illustrations of its nesting sites. 



No complain cs have been lodged against this bird by the farmer or 

 orchardist — in fact, it is too small to be able to do serious injury to 

 farm crops, and if it ate fruit it could injure only a few of the smaller 

 varieties. Nor has it been accused of eating honeybees, which are 

 probably too large to serve as its prey. 



For the study of the food of the western yellow-bellied flycatcher 

 157 stomachs were collected, mostly from California, with a few from 

 other Western States. They were taken in the months from March 

 to October and were very fairly distributed in time. The food was 

 found to consist of 99.31 per cent of animal matter to 0.69 per cent 

 of vegetable. The animal portion is made up of insects with a few 

 spiders, while the vegetable part consists of a few seeds and some 

 rubbish. 



Animal food. — Useful beetles amount to 2.45 per cent of the food, 

 and consist of predaceous ground beetles (Carabidse) found in 8 

 stomachs and ladybird beetles (Coccinellidae) in 24 or 16 per cent of 

 the whole number. This would seem to indicate that this bird has 

 a decided taste for coccinellids, though the percentage is not large. 

 As few other birds eat so many of these useful beetles, it is to be 

 inferred that this species selects them intentionally. It must be 

 understood that any bird that eats beetles in California is likely to 

 get a large number of coccinellids, even if it takes indiscriminately 

 all beetles that come in its way, for the family is wonderfully abundant 

 in that State. Other beetles amount to 5.94 per cent and are eaten 

 with considerable regularity through the season. The genus Bala- 



