Using Isotopic Variance to Detect Long-Distance Dispersal and Philopatry in Birds: An Example with Ovenbirds and American Redstarts

• Published in: The Condor
• Main Authors: Hobson, Keith A., Wassenaar, Leonard I., Bayne, Erin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2004
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Canada; Larga; Lac la Biche
• Online Access: http://dx.doi.org/10.1093/condor/106.4.732; http://academic.oup.com/condor/article-pdf/106/4/732/29711951/condor0732.pdf

Abstract Understanding movements of individual birds between breeding sites (breeding dispersal) or between natal sites and the site of first breeding (natal dispersal) is crucial to the modeling of population dynamics. Unfortunately, these aspects of demography are poorly understood for avian species in general, and for migratory songbirds in particular. This is because it is often impossible to sample broadly enough to relocate marked birds that have moved. We used stable-hydrogen (δD) and carbon (δ13C) isotope analyses of the feathers of 139 American Redstarts (Setophaga ruticilla) and 193 Ovenbirds (Seiurus aurocapillus) to evaluate evidence for individuals molting feathers at locations other than their breeding sites from the previous year. We sampled outer rectrices from breeding populations at three extensive boreal forest sites (Prince Albert National Park and Duck Mountain, Saskatchewan, and Lac La Biche, Alberta) and at three isolated forest tracts (Cypress Hills, and Moose Mountain, Saskatchewan, and Turtle Mountain, Manitoba) in western Canada. Based on outlier analysis of δD measurements, we found evidence for long-distance dispersal ranging from 0–29% of individuals. For both species, second-year birds had higher variance in δD values suggesting they had a higher probability of originating from elsewhere compared to after-second-year birds. Utilización de la Variación Isotópica para Detectar Dispersión de Larga Distancia y Filopatría en las Aves: Un ejemplo con Seiurus aurocapillus y Setophaga ruticilla Resumen. Entender los movimientos de aves individuales entre sitios de cría (dispersión reproductiva) o entre el sitio de nacimiento y el sitio del primer evento reproductivo (dispersión natal) es crucial para modelar la dinámica de poblaciones. Desafortunadamente, estos aspectos demográficos están poco entendidos para las especies de aves en general y para las aves canoras migratorias en particular. Esto se debe a que es usualmente imposible realizar muestreos lo suficientemente amplios como para ...