Establishing Winter Origins of Migrating Lesser Snow Geese Using Stable Isotopes

• Published in: Avian conservation and ecology 2012-06, Vol.7 (1), p.5-5, Article art5
• Main Authors: Hénaux, Viviane, Powell, Larkin A., Vrtiska, Mark P., Hobson, Keith A.
• Format: Article
• Language: English
• Subjects: carbon-13; Chen caerulescens; hydrogen-2; migratory connectivity; nitrogen-15; Rainwater Basin; Snow Goose; spring migration; stable isotope
• ISSN: 1712-6568; 1712-6568
• DOI: 10.5751/ACE-00515-070105

Increases in Snow Goose (Chen caerulescens) populations and large-scale habitat changes in North America have contributed to the concentration of migratory waterfowl on fewer wetlands, reducing resource availability, and enhancing risks of disease transmission. Predicting wintering locations of migratory individuals is critical to guide wildlife population management and habitat restoration. We used stable carbon ( delta super(13)C), nitrogen ( delta super(15)N), and hydrogen ( delta super(2)H) isotope ratios in muscle tissue of wintering Snow Geese to discriminate four major wintering areas, the Playa Lake Region, Texas Gulf Coast, Louisiana Gulf Coast, and Arkansas, and infer the wintering locations of individuals collected later during the 2007 and 2008 spring migrations in the Rainwater Basin (RWB) of Nebraska. We predicted the wintering ground derivation of migrating Snow Geese using a likelihood-based approach. Our three-isotope analysis provided an efficient discrimination of the four wintering areas. The assignment model predicted that 53% [95% CI: 37-69] of our sample of Snow Geese from the RWB in 2007 had most likely originated in Louisiana, 38% [23-54] had wintered on Texas Gulf Coast, and 9% [0-20] in Arkansas; the assessment suggested that 89% [73-100] of our 2008 sample had most likely come from Texas Gulf Coast, 9% [0-27] from Louisiana Gulf Coast, and 2% [0-9] from Arkansas. Further segregation of wintering grounds and additional sampling of spring migrating Snow Geese would refine overall assignment and help explain interannual variations in migratory connectivity. The ability to distinguish origins of northbound geese can support the development of spatially-adaptive management strategies for the midcontinent Snow Goose population. Establishing migratory connectivity using isotope assignment techniques can be extended to other waterfowl species to determine critical habitat, evaluate population energy requirements, and inform waterfowl conservation and management strategies.Original Abstract: L'accroissement des populations d'Oies des neiges (Chen caerulescens) et les changements d'habitat a grande echelle en Amerique du Nord ont contribue a la concentration de la sauvagine migratrice sur des milieux humides de moins en moins nombreux, a la diminution de la disponibilite des ressources alimentaires et a l'augmentation du risque de transmission de maladies. La capacite a prevoir les sites d'hivernage d'individus migrateurs est essentielle