Descriptions of the full Weekly Findings and links to more information.
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Importance of Eelgrass Beds at Izembek National Wildlife Refuge for Overwintering Migratory Waterfowl
Historically, nearly all black brant would migrate to Izembek Lagoon in southwest Alaska and feed on the extensive eelgrass beds there for 1-2 months before flying to wintering areas in Baja California, Mexico, but ice-free conditions now allow a substantial portion of the population to remain at Izembek throughout the winter. Although overwintering in Alaska allowed black brant to reduce their migration by 4500 km, they returned to their breeding areas at similar times and had similar rates of nest success regardless of where they spent the winter. This study highlights the importance of eelgrass beds at Izembek National Wildlife Refuge for migratory waterfowl throughout the year and represents an example of a migratory range shift associated with climate-driven changes in habitat availability. This paper is available at: https://doi.org/10.1186/s40462-025-00530-z. Learn More>>
Contact: Vijay Patil, Wildlife Biologist
Exposure of Wild Mammals to Influenza A(H5N1) Virus, Alaska, USA, 2020–2023
Blood serum samples from wild and apparently healthy mammals inhabiting Alaska showed that 4 species, including brown bears and red foxes, were previously exposed to highly pathogenic avian influenza H5N1 viruses. Results indicated that some of the mammals sampled survived the virus infection. Most detections of H5 and N1 in bear and fox samples originated from regions with extensive wetland complexes and where wild aquatic birds had been previously confirmed to be infected with highly pathogenic avian influenza H5N1. Surveillance efforts for avian influenza may be improved by incorporating information on susceptibility and detectable immune responses among wild mammals. This paper is available at: https://doi.org/10.3201/eid3104.241002. Learn More>>
Contact: Andrew Ramey, Research Wildlife Geneticist
Environmental Occurrence of Avian Influenza Virus Relative to Bait Trapping of Waterfowl
Bait trapping of waterfowl for banding and population monitoring purposes has been a common strategy used across North America to inform harvest management. Given significant and ongoing risks to wildlife associated with highly pathogenic (HP) avian influenza virus (AIV), there is interest in understanding whether and how various wildlife management interventions could amplify or reduce viral exposure among wild birds. Alaska Science Center Research Geneticist Andrew Ramey recently collaborated with a team of Canadian scientists to evaluate the occurrence of AIV in the environment relative to bait trapping. Results indicated that bait trapping was associated with localized increases in environmental occurrence of AIV such that baiting activities may pose a risk to wildlife population health through the propagation of HP AIV in wetlands and the waterfowl using those habitats. Efforts to replace, refine, or reduce wetland baiting activities may therefore be warranted depending on managements priorities, local ecosystem contexts, and cost‐benefit analyses. The paper can be found at: https://doi.org/10.1002/jwmg.22720. Learn More>>
Contact: Andrew Ramey, Research Wildlife Geneticist
Habitats of Historic and Contemporary Sea Otters for Managing Future Status and Trends
Dan Monson with the USGS Alaska Science Center, collaborated on a recent publication that used stable isotope values to determine past and current sea otter diets in Southeast Alaska and Northern Oregon, areas where otters are recolonizing and being considered for reintroductions, respectively. The study provides an important perspective for ongoing management efforts of sea otters and highlights the relevance of historical ecology. By integrating specimens from archaeological contexts with modern biological sampling via geochemical analyses, the study provided valuable insights into the long-term ecological dynamics of sea otters and the ability to forecast potential areas of human-wildlife conflict. The paper is available at https://doi.org/10.1098/rspb.2024.1682.
Contact: Dan Monson, Research Wildlife Biologist
Photogrammetry to Monitor Walrus Body Condition and Calf Growth
The U.S. Geological Survey has developed a new method to assess the body mass and condition of adult and young walruses with help from partners at zoos and aquariums. Using quiet drones flown high above herds resting on shore, scientists can assess the health of female walruses and their calves. This method also lays the groundwork to develop monitoring programs to track mortality events and calf survival. USGS scientists collaborated with zoos and aquariums in the United States, Belgium, and Germany to investigate the potential to use aerial imagery from drones to measure and estimate body mass of Pacific walruses. Measures from aerial imagery accurately distinguished reproductive age females from subadults and adult males and enabled body mass estimates with minimal error using either areal footprint or a combination of length and width. Analysis of body mass and size data available from walruses in the 1970s and 1980s followed patterns consistent with observed demographic changes. The study results suggest that body mass of reproductive age females and growth of dependent young may be useful indicators to augment monitoring of the Pacific walrus population and can be achieved via non-invasive aerial imagery collections. The study is available at: https://doi.org/10.3354/meps14738. Learn More>>
Contact: Karyn Rode, Research Wildlife Biologist
Assessing the Sustainability of Pacific Walrus Harvest
Researchers from the USGS Alaska Science Center and U.S. Fish and Wildlife Service developed a harvest sustainability model to evaluate the effects of harvest and climate/disturbance scenarios on walrus population dynamics to the end of the 21st century. Results suggest the current rate of harvest is sustainable, as long as it adapts to match future changes in population dynamics, but a non-adaptive harvest rate may also be sustainable at low levels if the population declines as expected. This tool was used in the forthcoming Species Status Assessment for the Pacific walrus and will be used to better guide co-stewardship of the population with Tribal partners. The paper is available in the Journal of Wildlife Management at: https://doi.org/10.1002/jwmg.22686. Learn More>>
Contact: Joe Eisaguirre, Research Wildlife Biologist
Descriptions of the full Weekly Findings and links to more information.
Return to Weekly Findings
Importance of Eelgrass Beds at Izembek National Wildlife Refuge for Overwintering Migratory Waterfowl
Historically, nearly all black brant would migrate to Izembek Lagoon in southwest Alaska and feed on the extensive eelgrass beds there for 1-2 months before flying to wintering areas in Baja California, Mexico, but ice-free conditions now allow a substantial portion of the population to remain at Izembek throughout the winter. Although overwintering in Alaska allowed black brant to reduce their migration by 4500 km, they returned to their breeding areas at similar times and had similar rates of nest success regardless of where they spent the winter. This study highlights the importance of eelgrass beds at Izembek National Wildlife Refuge for migratory waterfowl throughout the year and represents an example of a migratory range shift associated with climate-driven changes in habitat availability. This paper is available at: https://doi.org/10.1186/s40462-025-00530-z. Learn More>>
Contact: Vijay Patil, Wildlife Biologist
Exposure of Wild Mammals to Influenza A(H5N1) Virus, Alaska, USA, 2020–2023
Blood serum samples from wild and apparently healthy mammals inhabiting Alaska showed that 4 species, including brown bears and red foxes, were previously exposed to highly pathogenic avian influenza H5N1 viruses. Results indicated that some of the mammals sampled survived the virus infection. Most detections of H5 and N1 in bear and fox samples originated from regions with extensive wetland complexes and where wild aquatic birds had been previously confirmed to be infected with highly pathogenic avian influenza H5N1. Surveillance efforts for avian influenza may be improved by incorporating information on susceptibility and detectable immune responses among wild mammals. This paper is available at: https://doi.org/10.3201/eid3104.241002. Learn More>>
Contact: Andrew Ramey, Research Wildlife Geneticist
Environmental Occurrence of Avian Influenza Virus Relative to Bait Trapping of Waterfowl
Bait trapping of waterfowl for banding and population monitoring purposes has been a common strategy used across North America to inform harvest management. Given significant and ongoing risks to wildlife associated with highly pathogenic (HP) avian influenza virus (AIV), there is interest in understanding whether and how various wildlife management interventions could amplify or reduce viral exposure among wild birds. Alaska Science Center Research Geneticist Andrew Ramey recently collaborated with a team of Canadian scientists to evaluate the occurrence of AIV in the environment relative to bait trapping. Results indicated that bait trapping was associated with localized increases in environmental occurrence of AIV such that baiting activities may pose a risk to wildlife population health through the propagation of HP AIV in wetlands and the waterfowl using those habitats. Efforts to replace, refine, or reduce wetland baiting activities may therefore be warranted depending on managements priorities, local ecosystem contexts, and cost‐benefit analyses. The paper can be found at: https://doi.org/10.1002/jwmg.22720. Learn More>>
Contact: Andrew Ramey, Research Wildlife Geneticist
Habitats of Historic and Contemporary Sea Otters for Managing Future Status and Trends
Dan Monson with the USGS Alaska Science Center, collaborated on a recent publication that used stable isotope values to determine past and current sea otter diets in Southeast Alaska and Northern Oregon, areas where otters are recolonizing and being considered for reintroductions, respectively. The study provides an important perspective for ongoing management efforts of sea otters and highlights the relevance of historical ecology. By integrating specimens from archaeological contexts with modern biological sampling via geochemical analyses, the study provided valuable insights into the long-term ecological dynamics of sea otters and the ability to forecast potential areas of human-wildlife conflict. The paper is available at https://doi.org/10.1098/rspb.2024.1682.
Contact: Dan Monson, Research Wildlife Biologist
Photogrammetry to Monitor Walrus Body Condition and Calf Growth
The U.S. Geological Survey has developed a new method to assess the body mass and condition of adult and young walruses with help from partners at zoos and aquariums. Using quiet drones flown high above herds resting on shore, scientists can assess the health of female walruses and their calves. This method also lays the groundwork to develop monitoring programs to track mortality events and calf survival. USGS scientists collaborated with zoos and aquariums in the United States, Belgium, and Germany to investigate the potential to use aerial imagery from drones to measure and estimate body mass of Pacific walruses. Measures from aerial imagery accurately distinguished reproductive age females from subadults and adult males and enabled body mass estimates with minimal error using either areal footprint or a combination of length and width. Analysis of body mass and size data available from walruses in the 1970s and 1980s followed patterns consistent with observed demographic changes. The study results suggest that body mass of reproductive age females and growth of dependent young may be useful indicators to augment monitoring of the Pacific walrus population and can be achieved via non-invasive aerial imagery collections. The study is available at: https://doi.org/10.3354/meps14738. Learn More>>
Contact: Karyn Rode, Research Wildlife Biologist
Assessing the Sustainability of Pacific Walrus Harvest
Researchers from the USGS Alaska Science Center and U.S. Fish and Wildlife Service developed a harvest sustainability model to evaluate the effects of harvest and climate/disturbance scenarios on walrus population dynamics to the end of the 21st century. Results suggest the current rate of harvest is sustainable, as long as it adapts to match future changes in population dynamics, but a non-adaptive harvest rate may also be sustainable at low levels if the population declines as expected. This tool was used in the forthcoming Species Status Assessment for the Pacific walrus and will be used to better guide co-stewardship of the population with Tribal partners. The paper is available in the Journal of Wildlife Management at: https://doi.org/10.1002/jwmg.22686. Learn More>>
Contact: Joe Eisaguirre, Research Wildlife Biologist