Migratory connectivity in a declining bird species: using feather isotopes to inform demographic modelling

作者：Reichlin Thomas S^*; Hobson Keith A; Wassenaar Leonard I; Schaub Michael; Tolkmitt Dirk; Becker Detlef; Jenni Lukas; Arlettaz Raphael

来源：Diversity and Distributions, 2010, 16(4): 643-654.

DOI：10.1111/j.1472-4642.2010.00664.x

• Africa
• annual climatic variation
• isotopic variation (carbon-13
• nitrogen-15
• deuterium)
• Jynx torquilla
• leapfrog migration
• long-distance migrant
• species conservation

Aim
Conservation programmes for endangered migratory species or populations require locating and evaluating breeding, stopover and wintering areas. We used multiple stable isotopes in two endangered European populations of wrynecks, Jynx torquilla L., to locate wintering regions and assess the degree of migratory connectivity between breeding and wintering populations.
Location
Switzerland and Germany.
Methods
We analysed stable nitrogen (delta 15N), carbon (delta 13C) and hydrogen (delta D) isotopes from wing feathers from two populations of wrynecks to infer their wintering origins and to assess the strength of migratory connectivity. We tested whether variation in feather isotopic values within the Swiss population was affected by bird age and collection year and then considered differences in isotopic values between the two breeding populations. We used isotopic values of summer- and winter-grown feathers to estimate seasonal distributions. Finally, we calculated a species-specific delta D discrimination factor between feathers and mean annual delta D values to assign winter-grown feathers to origin.
Results
Bird age and collection year caused substantial isotopic variation in winter-grown feathers, which may be because of annually variable weather conditions, movements of birds among wintering sites and/or reflect asynchronous moulting or selection pressure. The large isotopic variance in winter-grown feathers nevertheless suggested low migratory connectivity for each breeding population, with partially overlapping wintering regions for the two populations.
Main conclusions
Isotopic variance in winter-grown feathers of two breeding populations of wrynecks and their geographical assignment point to defined, albeit overlapping, wintering areas, suggesting both leapfrog migration and low migratory connectivity. On this basis, integrative demographic models can be built looking at seasonal survival patterns with links to local environmental conditions on both breeding and wintering grounds, which may elucidate causes of declines in migratory bird species.

• 出版日期2010-7