Date FACTORS AFFECTING BODY MASS OF PREFLEDGING EMPEROR GEESE

• Main Authors: Bryce Cameron Lake, Joel A. Schmutz
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: TITLE PAGE ……; Napp; Yukon; Kuskokwim; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.383.5134; http://www.arlis.org/docs/vol1/D/62235249.pdf

Abstract: Body mass of prefledging geese has important implications for fitness and population dynamics. To address whether interspecific competition for forage was broadly relevant to prefledging emperor geese, I investigated the factors affecting body mass at three locations across the Yukon-Kuskokwim Delta, Alaska. From 1990 – 2004, densities of cackling geese more than doubled and were ~2 – 5x higher than densities of emperor geese, which were relatively constant over time. During 2003 – 2004, body mass of emperor geese increased with net above-ground primary productivity (NAPP) and grazing lawn extent and declined with interspecific densities of geese (combined density of emperor and cackling geese). Grazing by geese resulted in consumption of ≥ 90 % of the NAPP that occurred during the brood rearing period, suggesting that interspecific competition was due to exploitation of common food resources. At six sampled locations, grazing lawn extent varied among- and within-locations, and was stable or declined slightly during 1999 – 2004, indicating reduced per capita availability. I conclude that negative effects of interspecific goose densities on body mass of prefledging geese are partially responsible for recent declines in the fall age ratio of