Long-billed Gnatwren Ramphocaenus melanurus
Version: 2.0 — Published July 16, 2020
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Diet and Foraging
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Main Foods Taken
Microhabitat for Foraging
Food Capture and Consumption
An active forager, moving quickly through dense foliage, hopping from perch to perch, frequently leaning out to glean prey from leaves and twigs (361, 362). Long-billed Gnatwrens may forage alone, in pairs, or in small family groups (361, 363, 203, 16, 115), sometimes with mixed-species flocks. Willis (251) frequently found them associating with noisy foraging flocks of ant-tanagers (Habia) in Belize. In the Amazon there are scattered reports of Long-billed Gnatwrens joining mixed species assemblages attending army ant swarms (206). Indeed, Olalla (361) not only frequently found amazonum foraging with flocks, but felt that the gnatwrens might actually function as flock leaders and sentinels. He described how they vocalize at regular intervals while moving with the flock and, when alarmed, fall silent. Olalla (361) observed other flock members reacting to the cessation of gnatwren calls by halting foraging activities, seeking cover, and remaining motionless. Similar behavior has not been reported by any other observer of this widespread species, however.
Major Food Items
The diet of Long-billed Gnatwren has not been well documented, but it is presumed to feed on a variety of small invertebrates (32, 362). Hallinan (260) found small seeds and small insects in the stomach of a female rufiventris. Arthropods noted in examinations of stomach contents in Brazil (n = 9) were Aranae (spiders), Blattodea (cockroaches), Coleoptera (beetles; Cuculionidae), Formicidae (ants), Hemiptera (including Cicadellidae), Homoptera (Cicadidae larvae), Orthoptera (Acridiidae grasshoppers, unidentified orthopterans), and Termitidae (termites).(157, 364). Olalla (361) mentioned in passing that they also feed on caterpillars, but there appear to be no other specific records in the literature. With respect to food delivered to nestlings by the parents, Skutch (7) found it difficult to conclusively identify most prey items due to their small size, describing the nestling diet only as small moths and minute spiders.