282 SNODGRASS AND HELLER 



Point, Elizabeth Bay and Villa Mil, Albemarle, and along the east 

 shore of Narboro, depressions of the surface of considerable extent lie a 

 short distance back from the shore and these fill up with water at high 

 tide, but have generally no visible connection with the ocean. At such 

 places there occur large, dense groves of the mangrove tree and of 

 another tree, Avicennia, which is always associated with it. At high 

 tide the bases of these trees are covered several feet in depth, while 

 at low tide the floor of the swamp is generally exposed except for 

 scattered pools of water. It is only in the denser, interior parts of 

 such groves as these that Geospiza heliobates is found. The birds 

 seldom come out to the edge of the swamp, but they may easily be 

 taken if one can find a clear space near the center of the grove. 

 They are not timid or wary, but seem simply to prefer the denser and 

 more shaded parts of the swamps. Their food consists entirely of 

 insects which they obtain under the bark of the trees. 



The notes of this species are as distinctive of it as is its habitat. We 

 first heard the birds in January in the grove at Turtle Point, just 

 north of Tagus Cove, on Albemarle. The song resembled tur-tiir, 

 tiir-tur, tur-tiir, the set of two syllables being generally repeated 

 three times in succession, although sometimes more and sometimes 

 only twice. The sound was varied somewhat and often resembled 

 tiver-twer, ttver-twer. The notes are uttered rather loudly and have 

 a very striking sound when heard issuing from the depths of a dense 

 and apparently otherwise uninhabited grove. The birds seem to utter 

 the notes almost constantly, and their presence and location in a swamp 

 may always be known by their song. 



We observed the species in the swamps of the east shore of Nar- 

 boro during January, March and April, and did not perceive any dif- 

 ference between the habits or notes of the birds here and those at 

 Turtle Point, Albemarle. The species was also observed in two 

 large groves situated two or three miles apart, on the north shore of 

 southern Albemarle, a few miles west of Elizabeth Bay. It was at 

 once apparent, however, on listening to the birds of these swamps 

 that their song differed from that of the Tagus Cove and Narboro 

 birds. Instead of each set of notes in the song consisting of two syl- 

 lables, it consisted of three. Each trisyllabic set was repeated two or 

 three times just as with the others. The song, hence, resembled 

 tur-tiir-tur, tur-tur-tiir, tur-tur-tiir. Each swamp was visited twice ; 

 the birds were not scarce in either, and only now and then were bisyl- 

 labic sets heard. We visited the Turtle Point swamp again in March 

 and the birds here were singing, as before, their bisyllabic song. 



