Using stable hydrogen and oxygen isotope measurements of feathers to infer geographical origins of migrating European birds

Abstract

Successful application of stable-hydrogen isotope measurements (deltaDf) of feathers to track origins of migratory birds and other wildlife requires a fundamental understanding of the correlation between deltaDf and deuterium patterns in rainfall (deltaDp) over continental scales. A strong correlation between deltaDp and deltaDf has been confirmed for birds and insects in North America, but not yet for other continents. Here, we compare deltaDf data from resident European birds to new deltaDp basemaps for Europe. Three maps, representing growing-season and mean annual deltaDp estimates from an elevation-explicit, detrended interpolation model and growing-season deltaDp estimates from simple Kriging, all indicate that strong isotope gradients occur across Europe with a general depletion occurring in a northeast direction. The feather data, representing 141 individuals of 25 avian species from 38 sites, ranged from -131 to -38 per thousand. Regression analysis showed that strong correlations existed between both mean annual and growing-season deltaDp estimated by detrended interpolation and deltaDf of non-aquatic and non-corvid birds (r2=0.66 and 0.65, respectively). We also examined mean annual and growing-season delta18Op vs. delta18Of for our samples. Both oxygen regressions were similar (r2=0.56 and 0.57, respectively) but poorer than for deuterium. Our study reveals that deltaD measurements of feathers from migratory birds in Europe may be used to track their origin and movements, and so provide a powerful investigative tool for avian migration research in Europe.

A genetic characterization of European Woodcock (Scolopax rusticola,Charadriidae, Charadriiformes) overwintering in Italy

“…Although with few data corresponding to Hap-B, feathers belonging to both haplogroups showed H/D ratio corresponding to a wide range (from -86.8 to -33.8) of European rainfalls H/D values as mapped in Hobson et al (2004). However, the isotopic analysis highlighted a geographic differentiation of wintering individuals on the basis of their breeding origin: a clear separation between Northern (including Croatian samples) and Southern Italy (including Bulgarian samples) appeared.…”

“…Feathers H/D ratios were compared with a European rainfalls H/D ratio map (Hobson et al 2004) to infer the breeding origin of Italian samples. Analysis of H/D ratio was performed following Clegg et al (2003) protocol at the Geoscience and Georesources Institute of National Research Council, Pisa, Italy.…”

“…In long-distance migrants, molting occurs before migration and feathers sampled in overwintering or stop-over areas should reflect isotopic ratios of the breeding sites (Kelly & Finch 1998). Significant correlation of H/D ratios in rainfalls and locally grown feathers was described in North America (Hobson & Wassenaar 1997) as well as in Europe (Hobson et al 2004). This correlation has been used when studying population connectivity in several migratory birds (e.g.…”

“…These concentrations fluctuate in predictable patterns across Europe. In particular, hydrogen/deuterium (H/D) ratio shows a particular distribution with a depleting gradient from south-west to north-east (Hobson et al 2004). In long-distance migrants, molting occurs before migration and feathers sampled in overwintering or stop-over areas should reflect isotopic ratios of the breeding sites (Kelly & Finch 1998).…”

Invasion of BullfinchesPyrrhula pyrrhulain western Europe in 2004: a mix of local, ‘trumpeting’ birds and others of unknown origin

“…The larger pyrrhula race is known to be irruptive (Riddington & Ward 1998, Newton 2002) and ringing recoveries from Finland show that birds have occurred at localities between 1900 and 2350 km apart in different winters (Newton in press). Stable isotope analysis of feathers collected from birds caught in Denmark and elsewhere has been undertaken to see whether this technique can identify the regions of origin of these birds, as the isotope signatures reflect those in the environment where the feathers were grown (Hobson et al 2004). These results showed that large birds involved in the 2004 influx came from a wide geographical area, although this technique failed to identify differences between trumpeting and normalcalling large Bullfinches (Newton et al in press).…”