title: Morphometrics and stable isotopes differentiate wintering populations of a migratory bird.
abstract: BACKGROUND
  Describing migratory connectivity in mobile animals is crucial for understanding the selective pressures acting on different populations throughout their life cycle. Tracking single individuals has provided valuable data, but for most species the data available are still spurious and usually limited to a few individuals. Since different populations of migratory birds can be distinguished by a combination of morphometric measurements and the isotopic composition of their feathers, it is possible to measure these parameters on a large sample to differentiate populations.
  
  
  METHODS
  We studied northern wheatears, Oenanthe oenanthe, captured in their African wintering range and applied discriminant analyses on morphometric measurements and stable isotope signatures to determine whether birds found in different areas were distinguishable from each other.
  
  
  RESULTS
  Morphometric and isotopic measurements alone were not sufficient to discriminate between the birds of ssp. oenanthe from different areas in Africa. When combining the two measurements, however, assignment to the different groups became substantially more accurate. Following the discriminant analysis of morphometrics and δ(2)H, δ(13)C, and δ(15)N isotopes signatures, 19 of 20 oenanthe from Kenya, 15 of 20 oenanthe from Mali/Mauritania, and 19 of 20 oenanthe from Niger were assigned correctly to their wintering area.
  
  
  CONCLUSIONS
  Our results show that birds at different wintering sites can be distinguished from each other when using a combination of markers. We discuss the possible breeding origins of these wintering birds.
authors.affiliation: Institute of Avian Research "Vogelwarte Helgoland", Wilhelmshaven, Germany ; Konrad-Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Ivan
authors.identifier: 0000-0002-1528-2288
authors.initials: I
authors.lastname: Maggini
authors.affiliation: Institute of Avian Research "Vogelwarte Helgoland", Wilhelmshaven, Germany ; BirdLife Malta, Xemxija, Malta.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Metzger
authors.affiliation: Leibniz-Institute of Baltic Sea Research Warnemünde, IOW, Rostock, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Voss
authors.affiliation: Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
authors.forename: Christian C
authors.initials: CC
authors.lastname: Voigt
authors.affiliation: Institute of Avian Research "Vogelwarte Helgoland", Wilhelmshaven, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Bairlein
keywords: Connectivity; East Africa; Oenanthe oenanthe; Sahel; Wintering