AVIS-IBIS

Birds of Indian Subcontinent

Fitness Components Associated with Laying Date in the Cliff Swallow

Publication Type:Journal Article
Year of Publication:1999
Authors:Brown, CR, Brown, MBomberger
Journal:The Condor
Volume:101
Issue:2
Date Published:1999
ISBN Number:00105422
Keywords:Hirundinidae, Hirundo, Hirundo pyrrhonota, Hirundo rustica, Petrochelidon, Petrochelidon albifrons, Petrochelidon pyrrhonota
Abstract:We report how clutch size, annual reproductive success, and annual survival of breeders and offspring vary with laying date in Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, from 1982-1993. Clutch size declined significantly across the season for both parasite-free (fumigated) and naturally infested nests. Larger clutches of 4 and 5 eggs were initiated significantly earlier in warm and dry seasons; laying dates for smaller clutches showed no relationship with weather. Incubation period declined significantly with laying date and was shorter in the absence of ectoparasites. Fledging success declined significantly with laying date in nonfumigated nests, primarily through greater loss of nestlings to parasitic swallow bugs (Oeciacus vicarius). First-year survival probabilities of offspring varied significantly with date among nonfumigated nests but not among fumigated nests; earlier-hatched young survived best in some years, and in other years intermediate- or late-hatched young had highest survival. Number of young locally recruited was highest for early nesters in 5 of 7 years with intermediate nesters doing best in the remaining years. Annual survival of female breeders increased with laying date, suggesting a benefit to late nesting and a potential life history trade-off between reproduction and adult survival. Nestling body mass did not vary with laying date, suggesting no decline in food availability over the summer. Female body mass prior to and during laying declined significantly with laying date but during brood rearing increased significantly with laying date. Female body mass had no significant effect on clutch size independent of laying date. The primary environmental factor causing the seasonal decline in reproductive success is ectoparasitism. A seasonal decline in clutch size may be a strategic adjustment to reduce ectoparasitism by lowering the parasite carrying capacity per nest. Greater apparent survival of late-nesting females may prevent directional selection for earlier breeding times in Cliff Swallows.
URL:http://www.jstor.org/stable/1369986
Short Title:The Condor
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith