April 24, 2013: 'Migration Dynamics for Midcontinent Greater White-fronted Geese from Interior and Northwest Alaska'

Wednesday, April 24, 1 p.m. ConocoPhillips Integrated Science Building, Room 105A

The Department of Biological Sciences is pleased to have Wade Schock, graduate student in biological sciences, defend his thesis, "Migration Dynamics for Midcontinent Greater White-fronted Geese from Interior and Northwest Alaska." The graduate committee will consist of advisor Doug Causey, Ph.D., Jeffrey Welker, Ph.D., and Julian Fischer.

Abstract: This study is designed to better understand the migration demographics of midcontinent greater white-fronted geese (Anser albifrons frontalis) from Interior and Northwest Alaska, and test assumptions that geese migrating through the Delta Junction flyway represent a narrow geographic range of breeding grounds. This population has been a focus of concern, given that the abundance has fluctuated significantly over the last ten years with lower annual survival rates. Typical methods of assessing abundance, demography and source localities of birds on migration, however, have proven to be problematic and inaccurate. Schock utilized two innovative methods, high-resolution digital photography for migration demography and stable isotope analysis for natal sourcing, to quantify the migratory dynamics in 2010 and 2011. First, it was found that digital photography is effective and efficient in determining the proportion of juveniles to adults and identifying family groups. Over the duration of the migration periods for both years, differences were found in timing and trends of juvenile to adult ratios. Second, using multivariate discrimination analysis of stable isotope values of feathers, it was found that geese using the Delta Junction flyway comprised of birds from predicted breeding areas as well as a significant portion from other regions, most likely the northwestern part of the Alaskan coastal plain. In 2010, 28 percent of the migrant feather samples were categorized to two specific breeding areas. In 2011, 33 percent of the migrant feather samples were categorized to four breeding areas. Overall, Schock concluded these two techniques are effective in obtaining information about the migration demographics of midcontinent greater white-fronted geese from Interior and Northwest Alaska and, with additional study, could be used to obtain an index of annual production for this specific subpopulation.

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