title: Switching hemispheres: a new migration strategy for the disjunct Argentinean breeding population of Barn Swallow (Hirundo rustica).
abstract: BACKGROUND
  Barn Swallows (Hirundo rustica) breed almost exclusively in the Northern Hemisphere. However, since the early 1980's, a small disjunct breeding population has become established in eastern Argentina, presumably by birds previously derived from those breeding in North America. Currently, it is unknown where these individuals go following breeding and how they have adjusted to a reversal in phenology. Their austral wintering period corresponds to the breeding period of the northern ancestral population and so they can potentially return to these more traditional breeding sites or they may occupy other South American wintering regions left vacant by conspecifics returning to the Northern Hemisphere.
  
  
  RESULTS
  We used a three-isotope (δ(13)C, δ(15)N, δ(2)H) approach to investigate potential wintering areas in Central and South America of individuals breeding in Argentina. Feather isotope values differed from those expected and measured at local breeding sites in Argentina indicating molt after the austral breeding period and away from the breeding grounds. Potential molting origins were identified applying likelihood-based assignment methods to a δ(2)H isoscape for South America and dichotomous prior information on the distribution of C3 and C4 vegetation types based on modeled vegetation-δ(13)C values. Barn Swallows now breeding in Argentina have changed their migratory behavior but presumably use the same cues as those used by the ancestral population, molting their feathers during the austral winter, likely in north-eastern South America.
authors: Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. belen.garcia@usask.ca
authors: Belen
authors: B
authors: Garcia-Perez
authors: Keith A
authors: KA
authors: Hobson
authors: Rebecca L
authors: RL
authors: Powell
authors: Christopher J
authors: CJ
authors: Still
authors: Gernot H
authors: GH
authors: Huber
mesh_terms: D025041:Animal Migration; D000818:Animals; D001118:Argentina; D001947:Breeding; D005241:Feathers / Q000737:chemistry; D005843:Geography; D007554:Isotopes / Q000737:chemistry; D009656:North America; D011157:Population Dynamics; D012621:Seasons; D046388:Swallows / Q000502:physiology*
chemical_list: D007554:Isotopes
references: Biol Lett. 2012 Aug 23;8(4):505-7
references: 22337504
references: Oecologia. 2005 Apr;143(3):337-48
references: 15726429
references: PLoS One. 2012;7(4):e35137
references: 22509393
references: PLoS One. 2010 Mar 05;5(3):e9566
references: 20221266
references: Isotopes Environ Health Stud. 2003 Sep;39(3):211-7
references: 14521282
references: Ecol Appl. 2011 Jun;21(4):1340-51
references: 21774434
references: PLoS One. 2009 Nov 25;4(11):e7915
references: 19946360