Linking Breeding and Wintering Areas of King Eiders: Making Use of Polar Isotopic Gradients

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“…Stratification of breeding populations by winter provenance will likely provide a much-improved understanding of variation in breeding biology in other bird species and will help clarify the extent to which carry-over effects influence bird populations. Wilson, H. M., P. L. Flint, and A. N. Powell (2007 The basic form of the linear discriminant function of belonging to a particular group can be expressed as D group The linear classification equation using carbon and nitrogen isotopic ratios was: To calculate the probability of belonging to each population, the following equations (from Mehl et al 2005) were used:…”

“…Small size requires less material to replace feathers, and in turn, requires a shorter period of growth (Thompson and Drobney 1996). Thus, the average isotopic input can be incorporated into the tissue over a shorter time, perhaps representing reduced variation in isotopic landscapes sampled by foraging birds over a shortened temporal sampling frame (Mehl et al 2005). Even so, classification success (%) was much higher for Pacific than for Atlantic wintering birds (Table 3), possibly because of reduced heterogeneity in isoscapes used by Pacific scoters.…”

Stable isotopes can be used to infer the overwintering locations of prebreeding marine birds in the Canadian Arctic

“…Therefore, by matching tissue‐specific isotopic signatures to terrestrially delineated isotopic landscapes called isoscapes, stable isotopes have been successfully used to determine the overwintering or breeding areas of many terrestrial birds (Haché, Hobson, Villard, & Bayne, ; Hobson, ). Isoscapes of δ 2 H are generated as a result of predictable, regionally generalized patterns of precipitation (Bowen, Wassenaar, & Hobson, ; Mehl, Alisauskas, Hobson, & Merkel, ) and have proven useful for inferring the terrestrial overwintering grounds of various migrant bird species (Haché et al., ; Hénaux, Powell, Vrtiska, & Hobson, ; Hobson, Bowen, Wassenaar, Ferrand, & Lormee, ; Yerkes et al., ). Unlike deuterium, δ 13 C and δ 15 N isoscapes are generated by landscape‐scale processes related to nitrogen cycling in the soil (δ 15 N) and the plant types present (δ 13 C) (Bond & Jones, ; Rubenstein & Hobson, ).…”

“…The ability to apply stable isotope analysis to marine species is generally more challenging than terrestrial systems due to the highly dynamic nature of marine systems, which results in less predictable isoscapes, making isotope ratios collected from seabirds more difficult to define and interpret (Bond & Jones, ). To overcome the lack of reliable isoscapes in the marine environments, integrative ecologists have begun comparing the isotopic values from tissues in the species of interest with those occupying lower trophic positions (Mehl et al., ) as a proxy for the isotopic signal of the environment. For example, δ 15 N was used to infer the overwintering locations of breeding king eiders ( Somateria spectabilis ), by matching δ 15 N values in eider feathers, which were grown in winter, to signatures in copepod prey collected from two known overwintering areas located ~3,000 km apart (Mehl et al., ).…”

“…To overcome the lack of reliable isoscapes in the marine environments, integrative ecologists have begun comparing the isotopic values from tissues in the species of interest with those occupying lower trophic positions (Mehl et al., ) as a proxy for the isotopic signal of the environment. For example, δ 15 N was used to infer the overwintering locations of breeding king eiders ( Somateria spectabilis ), by matching δ 15 N values in eider feathers, which were grown in winter, to signatures in copepod prey collected from two known overwintering areas located ~3,000 km apart (Mehl et al., ). A limitation to this approach arises when comparing dissimilar tissues types (e.g., blood versus feathers), or when making interspecific comparisons, as tissue‐ or species‐specific discrimination factors are required to accurately relate the isotopic signatures of an animal to that of its prey (Bearhop et al., ; Bond & Diamond, ).…”