ANIMALS AS PASSIVE MEMBERS (COACTEES) 135 



of this habit. Among the well-known species, the brown creeper, bush 

 tit, barn and cliff swallows, chimney swift, house wren, nighthawk, 

 phoebe, wood pewee, purple martin, yellow-billed cuckoo, and yellow- 

 throated vireo rarely if ever consume vegetable matter, as is true in a 

 high degree of the white-headed and arctic three-toed woodpeckers. 

 Fruits and seeds constitute about 15 per cent of the food of king- 

 birds, kinglets, and pipits, though under compulsion this may rise 

 greatly, the last eating as much as 51 per cent in December. Approxi- 

 mately a fourth of the diet of the meadow lark, bluebird, chickadee, 

 and myrtle warbler consists of plant materials, and much the same 

 ratio obtains with the downy and hairy woodpecker and certain ant- 

 eating flickers. Beyond doubt, the more truly insectivorous birds 

 and the omnivorous forms that confine themselves to insects in the 

 summer make vast inroads on the insects of all climax communities 

 and their serai stages, but definite values cannot even be approximated 

 until quantitative studies are much more the rule (cf. McAtee, 1911). 



In the United States practically all species of bats live upon flying 

 insects, though frugivorous and sanguivorous types occur to the south- 

 ward. Dragonflies, some Hymenoptera (solitary wasps), and Diptcra 

 (robber flies) seize prey on the wing. In any one locality, an opening 

 made through a natural forest by a stream would be frequented by 

 certain birds and dragonflies during sunlight and by other birds and 

 bats soon after sundown and possibly by other bats as darkness comes 

 on or in the night. The different groups are thus out of direct com- 

 petition with one another as they encounter different prey. 



The cursorial type of insectivorous animals includes mammals, rep- 

 tiles, amphibians, and invertebrates; it is possible that some few birds 

 should be included. They are probably most important in the com- 

 munities of arid areas, though some are found in all regions. The 

 mammals that restrict their diet largely to termites are confined to 

 warm communities in the tropics and subtropics. The lizards are 

 chiefly insectivorous, though a few such as the desert iguana and the 

 chuckwalla are entirely herbivorous, and some, like the collared and 

 leopard lizards, feed upon plants as well as insects and other cold- 

 blooded animals. The larger number confine their attentions to in- 

 sects, though earthworms are sometimes added; some include slugs, 

 frogs, and other small lizards, and others like the "glass snake" and 

 the skunks vary the diet with bird eggs, nestlings, and young mice. 



Insects carnivorous in the broad sense are termed i)redaceous when 

 they capture other insects, spiders, etc. (Webster, 1880; Forbes, 

 1883, 6) ; however, many tend to be omnivorous. Those that suck the 

 blood of vertebrates, especially birds and mammals, may be regarded 



