Pacific brant are an Arctic-breeding sea goose that stage and feed on seagrasses during the non-breeding season in coastal areas of Alaska. Brant are an important subsistence and sport harvest species and the focus of several population surveys by state and federal agencies. Each fall the entire population stages during migration in Izembek Lagoon, Alaska, presenting a unique opportunity to survey the proportion of young and derive and index of annual productivity.
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Since 1963, the USGS and U.S. Fish and Wildlife Service have conducted surveys to record the number of juvenile (i.e., first-year birds) and adult (i.e., birds ≥ 2 years old) Pacific brant (Branta bernicla nigricans) and estimate the age ratio (number of juvenile birds compared to total birds aged) for the overall population. This fall age ratio estimate is the only measure of annual productivity for the entire population and a potential index of recruitment (i.e., number of young produced per female) given that most first-year mortality in Pacific brant occurs between hatch and migration to Izembek. USGS recently published model-based age ratio estimates through 2015 suggesting a slow decline in brant productivity (Ward et al. 2018). However, age ratios have improved in recent years and although they vary widely, general trends appear stable.
To provide up-to-date information for managers, USGS will publish age ratio data and model-based age ratio estimates annually on this site - data are currently available through 2021.
Data
Data Download [81KB] | Metadata | Version History
Citation: Patil, V.P., Amundson, C.L., Ward, D.H., Williams, A.R., 2020, Data and model-based estimates from Black brant (Branta bernicla nigricans) fall age ratio surveys at Izembek Lagoon, Alaska (ver 4.0, January 2023): U.S. Geological Survey data release, https://doi.org/10.5066/P9QIJIU2
(Credit: Vijay Patil, USGS)
Below are other science projects associated with this project.
Ecosystems Analytics
Waterfowl Research
- Overview
Pacific brant are an Arctic-breeding sea goose that stage and feed on seagrasses during the non-breeding season in coastal areas of Alaska. Brant are an important subsistence and sport harvest species and the focus of several population surveys by state and federal agencies. Each fall the entire population stages during migration in Izembek Lagoon, Alaska, presenting a unique opportunity to survey the proportion of young and derive and index of annual productivity.
Return to Ecosystems >> Terrestrial Ecosystems >> Waterfowl Research
Sources/Usage: Public Domain.Brant family on the breeding grounds prior to migrating to Izembek Lagoon, Alaska. (Credit: Jeff Wasley, U.S. Geological Survey. Public domain.) Since 1963, the USGS and U.S. Fish and Wildlife Service have conducted surveys to record the number of juvenile (i.e., first-year birds) and adult (i.e., birds ≥ 2 years old) Pacific brant (Branta bernicla nigricans) and estimate the age ratio (number of juvenile birds compared to total birds aged) for the overall population. This fall age ratio estimate is the only measure of annual productivity for the entire population and a potential index of recruitment (i.e., number of young produced per female) given that most first-year mortality in Pacific brant occurs between hatch and migration to Izembek. USGS recently published model-based age ratio estimates through 2015 suggesting a slow decline in brant productivity (Ward et al. 2018). However, age ratios have improved in recent years and although they vary widely, general trends appear stable.
To provide up-to-date information for managers, USGS will publish age ratio data and model-based age ratio estimates annually on this site - data are currently available through 2021.
Data
Data Download [81KB] | Metadata | Version History
Citation: Patil, V.P., Amundson, C.L., Ward, D.H., Williams, A.R., 2020, Data and model-based estimates from Black brant (Branta bernicla nigricans) fall age ratio surveys at Izembek Lagoon, Alaska (ver 4.0, January 2023): U.S. Geological Survey data release, https://doi.org/10.5066/P9QIJIU2
Sources/Usage: Public Domain.Model-based estimates of Pacific brant age ratios (juveniles:adults) in Izembek Lagoon, Alaska 1963-2022.
(Credit: Vijay Patil, USGS) - Science
Below are other science projects associated with this project.
Ecosystems Analytics
Ecosystems Analytics is a group of quantitative biologists and research statisticians with a diverse range of expertise and experience (summarized below). We collaborate with internal and external partners to answer challenging ecological questions that are a high priority of the U.S. Geological Survey Alaska Science Center, sister agencies within the Department of the Interior (DOI), and various...Waterfowl Research
Scientists at the USGS Alaska Science Center have conducted research on waterfowl species (ducks, geese, and swans) in Alaska since the 1970s. Because Alaska is an international crossroads of migratory bird flyways, with millions of birds from Asia and North America breeding in Alaska each summer, USGS research has also taken place in adjacent countries (Russia, Japan, Canada, Mexico) and in the... - Publications