Chilean Swallows (Tachycineta meyeni) adjust the number of feathers added to the nest with time of breeding

MARCELA LILJESTHROM; ADRIAN SCHIAVINI; JUAN CARLOS REBOREDA

WILSON JOURNAL OF ORNITHOLOGY

WILSON ORNITHOLOGICAL SOC

Año: 2009 vol. 121 p. 783 - 788

1559-4491

Tachycineta swallows nest in secondary cavities and build nests made of a mat of dry grasses with a nestcup lined with feathers. The insulative quality of feathers may prevent hypothermia of the chicks and increase chick growth,but also may raise the risk of nestling hyperthermia if ambient temperature is high. The number of feathers added to the nestshould vary throughout the breeding season according to ambient temperature. We describe nest structure and timing ofnest building of Chilean Swallows (Tachycineta meyeni) nesting in Tierra del Fuego, Argentina. We analyzed theassociation between number of feathers in the nest and (1) daily ambient temperature during the period swallows addfeathers to the nest, and (2) hatching success of eggs and survival and growth of the chicks. There was a negativeassociation between number of feathers added to the nest and average daily ambient temperature during the nesting cycle.Hatching success was not associated with number of feathers at start of laying or at the end of incubation. There was noassociation between number of feathers and chick survival or between number of feathers and average weight of the chickswhen they were 12 and 15 days of age. Chilean Swallows make temporal adjustments to the number of feathers added tothe nest. We suggest these adjustments may help maintain reproductive success throughout the breeding season