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Swallows of the family Hirundinidae are small, adept aerialists with long, pointed wings and deeply forked tails. Although their bills are short, their mouths are wide for capturing flying insects. Overall, swallows resemble swifts but have stronger, more fluid flight. Highly gregarious, they form large flocks and may be seen perched in long rows along branches or wires. Three species of swallows occur in Yukon-Charley Rivers National Preserve; Violet-green, Tree and Bank Swallows. Violet-green Swallows are named for their beautiful, iridescent plumage. Their genus name, Tachycineta, means “fast-moving” and refers to their rapid flight.Descriptions: Violet-green Swallows are common in montane, coniferous-deciduous woodlands. They were also found above treeline in sedimentary rock formations that provided nesting cavities within Yukon-Charley Rivers National Preserve. As their name implies, these small, 13cm swallows are vibrant emerald and violet above with bright, white underparts. Very short-tailed, their wingtips project well beyond the tips of their tails. Confused only with the Tree Swallow, the Violet-green Swallow may be distinguished by the large, white flank patches extending over the sides of the rump and white cheek patches extending over the eyes. Juveniles are gray-brown above, mottled-white below and lack the white extending above the eyes in the adults.
Vocalizations: The song of the Violet-green Swallow is a creaking “teer, twee, tsip, tsip, tsip.” Their calls are harsher “chilp” or “chil-lip” notes. When alarmed, the call is a clear and descending series of repeated “seer” or “teewp” notes.
Nests: Violet-green Swallows nest in tree-cavities, snags, rock crevices or nest boxes. These swallows nest singly and compete for nest cavities with other species. Nests are woven of grasses and lined with feathers. A clutch consists of 4-6, 19mm, white and unmarked eggs. The female alone incubates the clutch for 13-14 days and young birds fledge in another 16-24 days. Both parents care for the offspring.
Diet: The diet of the Violet-green Swallow is composed of insects. These birds are elegant fliers and dart to catch flying insects in aerial pursuit.
Distribution: At the end of the summer, Violet-green Swallows aggregate in enormous, pre-migratory, communal roosts of up to 100,000 birds! Often, they form mixed flocks with Tree Swallows. They winter in South America and Honduras. In summer, they range throughout central and southern Alaska and Yukon, and southward along the Pacific Coast to Mexico. Within Yukon-Charley Rivers National Preserve, these birds were detected in just two ecological units during the Yukon-Charley Rivers National Preserve Bird Inventory, June 1999 and 2000. Only two Violet-green Swallows were encountered in the forests of the Ogilvie Foothills (OF) and the Tintina Hills (TH) ecological units. Violet-green Swallows are expected to be more numerous in the Preserve, but swallow species in general were not well inventoried using our survey technique.
