Increased body mass of ducks wintering in California's Central Valley

Journal of Wildlife Management
By: , and 

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Abstract

Waterfowl managers lack the information needed to fully evaluate the biological effects of their habitat conservation programs. We studied body condition of dabbling ducks shot by hunters at public hunting areas throughout the Central Valley of California during 2006–2008 compared with condition of ducks from 1979 to 1993. These time periods coincide with habitat increases due to Central Valley Joint Venture conservation programs and changing agricultural practices; we modeled to ascertain whether body condition differed among waterfowl during these periods. Three dataset comparisons indicate that dabbling duck body mass was greater in 2006–2008 than earlier years and the increase was greater in the Sacramento Valley and Suisun Marsh than in the San Joaquin Valley, differed among species (mallard [Anas platyrhynchos], northern pintail [Anas acuta], America wigeon [Anas americana], green-winged teal [Anas crecca], and northern shoveler [Anas clypeata]), and was greater in ducks harvested late in the season. Change in body mass also varied by age–sex cohort and month for all 5 species and by September–January rainfall for all except green-winged teal. The random effect of year nested in period, and sometimes interacting with other factors, improved models in many cases. Results indicate that improved habitat conditions in the Central Valley have resulted in increased winter body mass of dabbling ducks, especially those that feed primarily on seeds, and this increase was greater in regions where area of post-harvest flooding of rice and other crops, and wetland area, has increased. Conservation programs that continue to promote post-harvest flooding and other agricultural practices that benefit wintering waterfowl and continue to restore and conserve wetlands would likely help maintain body condition of wintering dabbling ducks in the Central Valley of California.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Increased body mass of ducks wintering in California's Central Valley
Series title Journal of Wildlife Management
DOI 10.1002/jwmg.1053
Volume 80
Issue 4
Year Published 2016
Language English
Publisher Wildlife Society
Publisher location Washington, D.C.
Contributing office(s) Western Ecological Research Center
Description 12 p.
First page 679
Last page 690
Country United States
State California
Other Geospatial Central Valley
Online Only (Y/N) N
Additional Online Files (Y/N) N