A Morphometric Study Of The White Fronted Geese Wintering In California

Author : Daniel Adam Skalos
Publisher :
ISBN 13 : 9781267760043
Total Pages : pages
Book Rating : 4.7/5 (6 download)

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Download or read book Evaluating Body Condition and Predicting Lipid Mass of Wintering Pacific Greater White-fronted Geese (Anser Albifrons Frontalis) written by Daniel Adam Skalos and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Within the past 30 years significant changes to waterfowl habitat have occurred within the Sacramento Valley of California and the Klamath Basin of California and Oregon. Understanding the impacts of these changes on waterfowl body condition is critical for management of waterfowl populations within the Pacific Flyway. We collected Pacific Greater White-fronted (Anser albifrons frontalis) geese during the winters of 2009-10 and 2010-11 to compare to geese collected by Ely and Raveling (1989) during 1980-81, in order to evaluate changes of habitat on seasonal body condition of this species. We analyzed body condition by way of fat reserves from lipid extraction of goose carcasses. We found seasonal (Day) and yearly (Year) fluctuations in body condition to be evident in both males and females. Geese collected in the Klamath Basin during October contained similar lipid reserves during 1980 and 2009, but decreased considerably in 2010. The decrease in overall fat reserves observed in 2010 corresponded to a decrease in cereal grain production and refuge flooding during the fall 2010 in the Klamath Basin. The decrease in grain production and refuge flooding was due to poor winter snowpack causing inadequate water stores for irrigation. Geese collected during both December and January within the Sacramento Valley contained more fat in 2009-10 than 2010-11 and 1980-81. We found no clear differences in fat reserves between either study during December and January. Similar to October, geese collected in the Klamath Basin during March contained substantially less fat reserves in 2011 than 2009 and 1980. This further supports the negative effect of insufficient waste grain availability in this region. Furthermore, males appeared to have a trend of lower body condition in March during our study. Geese increased body fat significantly within the month of April prior to migration. We analyzed April by first half and second half due to its dynamic nature. Males continued March trends into the first half of April, containing less fat reserves during our study. No males were collected during the second half of April in 1981; however, males in our study increased fat reserves dramatically. Females collected in 2011 during the first half of April contained surprisingly less fat reserves than geese collected in 2010 and 1981. Furthermore, females doubled, and in the case of 2011, tripled fat reserves during the second half of April. Although we did not observe large differences in body condition between studies, we did observe the effects of reduced cereal grain forage within the major spring staging area of the Klamath Basin. Geese change diet from cereal grain to green forage late in spring so it is unclear if these limitations have had negative impacts on fitness within this population. Further research on Greater White-fronted geese and other species of waterfowl that depend on the Klamath Basin as a spring staging area is warranted to better understand the effect of limited food resources in this critical staging area of the Pacific Flyway.