title: Toward a Deuterium Feather Isoscape for Sub-Saharan Africa: Progress, Challenges and the Path Ahead.
abstract: A key challenge to the application of continent-wide feather isoscapes for geographic assignment of migrant birds is the lack of ground-truthed samples. This is especially true for long-distance Palearctic-Afrotropical migrants. We used spatially-explicit information on the δ2H composition of archived feathers from Green-backed/Grey-backed Camaroptera, to create a feather δ2H isoscape for sub-Saharan Africa. We sampled from 34 out of 41 sub-Saharan countries, totaling 205 sampling localities. Feather samples were obtained from museum collections (n = 224, from 1950 to 2014) for δ2H assay. Region, altitude, annual rainfall and seasonal patterns in precipitation were revealed as relevant explanatory variables for spatial patterns in feather δ2H. Predicted feather δ2H values ranged from -4.0 ‰ to -63.3 ‰, with higher values observed in the Great Rift Valley and South Africa, and lower values in central Africa. Our feather isoscape differed from that modelled previously using a precipitation δ2H isoscape and an assumed feather-to-precipitation calibration, but the relatively low model goodness fit (F10,213 = 5.98, p<0.001, R2 = 0.18) suggests that other, non-controlled variables might be driving observed geographic patterns in feather δ2H values. Additional ground-truthing studies are therefore recommended to improve the accuracy of the African feather δ2H isoscape.
authors.affiliation: Departamento de Biología de la Conservación, Estación Biológica de Doñana (CSIC), Sevilla, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Gutiérrez-Expósito
authors.affiliation: Departamento de Biología de la Conservación, Estación Biológica de Doñana (CSIC), Sevilla, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Ramírez
authors.affiliation: Laboratorio de SIG y Teledetección (LAST-EBD), Estación Biológica de Doñana (CSIC), Sevilla, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Afán
authors.affiliation: Departamento de Biología de la Conservación, Estación Biológica de Doñana (CSIC), Sevilla, Spain.
authors.forename: Manuela G
authors.initials: MG
authors.lastname: Forero
authors.affiliation: Environment Canada, Saskatoon, Saskatchewan, Canada.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Hobson
mesh_terms: D017954:Africa South of the Sahara; D000818:Animals; D001717:Birds / Q000378:metabolism; D016001:Confidence Intervals; D003903:Deuterium / Q000378:metabolism*; D005241:Feathers / Q000378:metabolism*; D005843:Geography; D008954:Models, Biological; D012044:Regression Analysis
chemical_list: D003903:Deuterium