title: Modelling the progression of bird migration with conditional autoregressive models applied to ringing data.
abstract: Migration is a fundamental stage in the life history of several taxa, including birds, and is under strong selective pressure. At present, the only data that may allow for both an assessment of patterns of bird migration and for retrospective analyses of changes in migration timing are the databases of ring recoveries. We used ring recoveries of the Barn Swallow Hirundo rustica collected from 1908-2008 in Europe to model the calendar date at which a given proportion of birds is expected to have reached a given geographical area ('progression of migration') and to investigate the change in timing of migration over the same areas between three time periods (1908-1969, 1970-1990, 1991-2008). The analyses were conducted using binomial conditional autoregressive (CAR) mixed models. We first concentrated on data from the British Isles and then expanded the models to western Europe and north Africa. We produced maps of the progression of migration that disclosed local patterns of migration consistent with those obtained from the analyses of the movements of ringed individuals. Timing of migration estimated from our model is consistent with data on migration phenology of the Barn Swallow available in the literature, but in some cases it is later than that estimated by data collected at ringing stations, which, however, may not be representative of migration phenology over large geographical areas. The comparison of median migration date estimated over the same geographical area among time periods showed no significant advancement of spring migration over the whole of Europe, but a significant advancement of autumn migration in southern Europe. Our modelling approach can be generalized to any records of ringing date and locality of individuals including those which have not been recovered subsequently, as well as to geo-referenced databases of sightings of migratory individuals.
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ambrosini
authors.affiliation: Dipartimento di Economia, Metodi quantitativi e Strategie di Impresa, Università degli Studi di Milano-Bicocca, Milano, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Borgoni
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Rubolini
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milano, Italy.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Sicurella
authors.affiliation: Max Plank Institute for Ornithology, Vogelwarte Radolfzell, Radolfzell, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Fiedler
authors.affiliation: Institute of Avian Research "Vogelwarte Helgoland", Wilhelmshaven, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Bairlein
authors.affiliation: British Trust for Ornithology, Thetford, United Kingdom.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Baillie
authors.affiliation: British Trust for Ornithology, Thetford, United Kingdom.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Robinson
authors.affiliation: British Trust for Ornithology, Thetford, United Kingdom.
authors.forename: Jacquie A
authors.initials: JA
authors.lastname: Clark
authors.affiliation: Istituto Superiore per la Protezione e la Ricerca Ambientale, Ozzano dell'Emilia (BO), Italy.
authors.forename: Fernando
authors.initials: F
authors.lastname: Spina
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Saino
mesh_terms: D000352:Africa, Northern; D025041:Animal Migration; D000818:Animals; D005060:Europe; D008954:Models, Biological; D015233:Models, Statistical; D012621:Seasons; D046388:Swallows / Q000502:physiology*