349 



RIVER FLIES 



AS THE FOOD OF THE PIED FLYCATCHER 

 AND OTHER BIRDS. 



Miss MARY L. ARIMITT. 

 Rydal, Wesimorland. 



The Pied Flycatchers are in June at their busiest time of family 

 life, as their young-sters are feathering- and g-rowing- fast. In 

 one nest by the river's brink seven little ones are crowded in 

 a heap, only to be counted by the mottled heads, the yellow 

 beaks, and the spreckled breasts. They may be heard squeal- 

 ing hungrily as they anticipate and take the food which the 

 parents bring-. This food is almost all gathered from the river, 

 and is mostly the product of its waters. Certain river flies 

 I have long known to be a favourite food with these birds, and 

 three species of them, very similar in appearance, have been 

 kindly named for me by Mr. G. T. Porritt. They are Chloro- 

 perla grammatica, a large yellow-green species often seen 

 sticking in the beak of the bird ; Isopteryx tripunctata, a smaller 

 species ; and Isopteryx torrenfmni, a darker one, which is 

 doubtless also taken. This year I noticed the first appearance of 

 these flies on May 30th, quite a week later than last year, and 

 since then they have been very abundant. At noon they may 

 be seen rising from the river in numbers, their four wings 

 glittering in sunshine. They make a diagonal course to the 

 foliage, where they creep about, their large wings folded flat. 

 On cold, cloudy days (of which we have had a few without 

 rain) they rise less. The Pied Flycatcher then appears a some- 

 what sluggish bird, drifting from rock to rock in the low- 

 running stream, and apparently picking up the flies where they 

 lie. But on sunny days it takes them in swift flight from tree 

 to tree, or snaps them off" the leaves. 



This is not the only food, however, that the bird carries to 

 its youngsters. Their diet is varied, and appears to be more 

 various when the nest is placed farther from the water. Small, 

 hard morsels, that look like beetles, are often taken to the nest, 

 and I have been able to distinguish the Brackenclock [Phyllo- 

 pertha horticola) and a brown beetle {Lagria hirta?) when these 

 are abundant. Spiders, too, are taken. These are almost 

 certainly the LycoscF, or wolf spiders, which the bird watches 



1903 September i. 



