title: GIS-based model of stable hydrogen isotope ratios in North American growing-season precipitation for use in animal movement studies.
abstract: Stable hydrogen isotope ratios of precipitation (deltaD(p)) show distinct geographic patterns across North America. Over the last decade, ecologists have utilized growing-season deltaD(p) patterns to study the movements of migratory animals. The accuracy and precision of such studies is, in part, contingent upon the accuracy and precision of growing-season deltaD(p) maps. Previous mapping efforts have employed simple kriging procedures to produce smooth contor maps of growing-season deltaD(p). We attempted to improve these maps by incorporating the effects of altitude on both deltaD(p) values and growing season length. This involved producing elevation-corrected monthly deltaD(p), temperature, and precipitation amount values for 1-km grid cells across the continental United States and Canada using recently developed interpolation procedures. We used a geographic information system (GIS) to calculate a weighted-average growing-season deltaD(p) value for each grid cell using deltaD(p) and precipitation amount values for all months in which the mean temperature was greater than 0 degrees C. We used seven independent data sets to compare the precision of the resulting altitude-corrected map with another that did not account for altitude. Overall, predicted deltaD(p) values from the altitude-corrected map more closely matched observed values, and correspondence was more pronounced at finer spatial scales. Digital versions of the GIS-based maps generated during this effort are available via the Internet at http://biology.unm.edu/wolf/precipitationD.htm. These deltaD(p) layers can be combined with other types of spatial information, such as species' geographic ranges and habitat associations, to further improve our understanding of animal movements.
authors.affiliation: Department of Biology and Museum of Southwestern Biology, The University of New Mexico, Albuquerque, NM 87131, USA. tdmeehan@unm.edu
authors.forename: Timothy
authors.initials: T
authors.lastname: Meehan
authors.forename: J Tomasz
authors.initials: JT
authors.lastname: Giermakowski
authors.forename: Paul
authors.initials: P
authors.lastname: Cryan
mesh_terms: D000383:Agriculture; D000531:Altitude; D025041:Animal Migration; D000818:Animals; D002170:Canada; D003903:Deuterium / Q000032:analysis*; D004777:Environment; D040362:Geographic Information Systems; D008962:Models, Theoretical; D011891:Rain; D015203:Reproducibility of Results; D012621:Seasons; D012914:Snow; D013696:Temperature; D014481:United States
chemical_list: D003903:Deuterium