BIRDS OF PORTO RICO. 103 



a high altitude were in the limestone hills west of Cayey, at about 1,200 feet 

 elevation, the birds being found elsewhere mainly below 500 feet. They are 

 fairly common on Vieques also, and this is the first time they have been recorded 

 from that island. 



On the south side of Porto Rico they are found in dry forest growth covering 

 the hills, and on the north coast in second-growth forest tangled with vines 

 and creepers, and where these conditions are wanting the birds are not found. 

 Quick and active in habits, they feed rapidly through the tips of the twigs., 

 tumbling down through the limbs after a moth or flying out to capture an es- 

 caping insect on the wing. They are partial to dense tangles of vines, and, 

 though not wild, it was sometimes hard to find them for this reason. The song 

 of the male is a sudden trilling outburst, somewhat like that of the pine warbler 

 (Dendroica v. vigorsi), and always there follow protesting notes from a female 

 near by. The males sing at short intervals during the forenoon and evening 

 and occasionally during the heat of the day. Many were seen along the Rio 

 de la Lapa, back of Salinas, where they were exceptionally abundant. 



The birds appear to nest in May and June, and young were first observed near 

 Quebradillas July 3, but after that date they were common. Near Yauco, on 

 May 22, a nest was found in a thicket, not quite completed. It was saddled in a 

 forked limb of a bush, about 4 feet from the ground. Externally its construc- 

 tion was of gray moss, shading in perfectly with its surroundings, while the 

 lining was of fine grass. Bowdish (1902-3, p. 18) secured a juvenal male near 

 Aguadilla June 15. The birds were molting badly in August. 



Food. — For detailed analysis 41 stomachs of this bird were available, taken 

 in every month from December to August except June. These contained noth- 

 ing but animal matter. Six birds had secured Orthoptera, 2.61 per cent of 

 the total. Three of these had eaten grasshoppers (Locustidse). Insects that 

 were actually identified as lantern flies amount to 46.82 per cent, and were 

 found in 24 of the stomachs, while remains definitely determined only as those 

 of small homopterous insects come to 12.73 per cent more. Thus these insects, 

 destructive to many cultivated plants, form a little more than two-thirds of 

 the entire food. Other bugs, assassin bugs in two instances, form 1.84 per cent. 

 One bird had taken 12 stinkbug eggs. 



Beetles are well represented and, with the exception of ladybird beetles in 

 three instances (0.05 per cent), are all harmful species. Skin beetles come to 

 0.28 per cent and longicorns to 5.81 per cent. Leaf beetles (1.92 per cent) were 

 eaten by 11 birds. Among the weevils, curculios, found in seven instances, come 

 to 3.33 per cent and other snout beetles amount to 2.53 per cent. A few miscel- 

 laneous Coleoptera remains figure as 0.36 per cent. Caterpillars were eaten 6 

 times and moths 11, all amounting to 11.23 per cent. Hymenoptera comprise 

 2.12 per cent of the food, and are mostly small parasitic species, though ants 

 were eaten three times. Spiders (7.29 per cent) were eaten 14 times. Diptera 

 comprise only 0.45 per cent, and miscellaneous animal matter 0.63 per cent. One 

 tree toad (Eleutherodactylus sp.) was eaten. 



Adelaide's warbler is one of the few endemic birds that draw their entire 

 sustenance from the animal kingdom. Enormous numbers of small Homoptera 

 are destroyed by these birds ; in fact, from this group of insects alone is gathered 

 more than two-thirds of the bird's entire aliment. Besides these, many harmful 

 weevils and other beetles, caterpillars, moths, and other insects are destroyed. 

 In capturing small numbers of ladybird beetles, parasitic Hymenoptera, and 

 spiders, some damage is done, but this is compensated for many times over by 

 the great numbers of injurious insects which form the bulk of the food. 



