The greater scaup (Aythya marila) is a species of diving duck found across the northern parts of North America, Europe, and Asia. It breeds in the boreal forest wetlands of Alaska, Canada, and the northern United States during the summer, and migrates south to coastal estuaries and bays during the winter. The greater scaup has experienced significant population declines since the 1980s, leading to concern about its conservation status. In this article, we will examine whether the greater scaup is currently endangered or threatened with extinction.
Current Conservation Status
The greater scaup is not currently listed as endangered or threatened at the global population level by the International Union for Conservation of Nature (IUCN) Red List. The IUCN Red List categorizes the greater scaup as “Least Concern” with a stable population trend. However, some national and regional assessments have listed the greater scaup as a species of conservation concern due to declining local populations.
In the United States, the greater scaup is not listed as endangered or threatened under the Endangered Species Act. However, it is listed as a “Bird of Conservation Concern” by the U.S. Fish and Wildlife Service because of declining breeding populations and habitat concerns. The breeding population in Alaska, which accounts for an estimated 59% of the global breeding population, has declined significantly since the 1980s.
Population Status and Trends
The total global population of greater scaup is estimated at 4.5 million birds. Global population trends from 1966-2015 are shown in the table below:
Time Period | Estimated Global Population | Population Trend |
---|---|---|
1966-2014 | 6.1 million | Declining |
1999-2014 | 4.5 million | Stable |
As the table shows, the global greater scaup population underwent a long-term decline from 1966-2014, with the population decreasing from an estimated 6.1 million to 4.5 million birds over that time period. However, the population has been relatively stable over the past couple of decades since 1999.
When looking at specific flyways and wintering grounds, some populations have declined more severely than others:
– The continental population that winters in the Interior Highlands of the Mississippi Flyway has declined by an estimated 65% between 1978 and 2007.
– Breeding populations in Alaska declined by an estimated 90% between the 1980s to early 2000s. The population in Alaska seems to have stabilized in the past decade but remains far below historical numbers.
– Breeding populations in the boreal forest wetlands of Canada have also experienced significant declines, but perhaps not as steep as Alaska.
So while the global population trend may be stable now, the historical declines and continued downward trends in certain flyways are cause for concern about the long-term health of the greater scaup population.
Threats and Causes of Decline
Several factors are thought to be contributing to the decline of greater scaup populations since the 1980s, including:
– **Habitat degradation:** Loss of wetland breeding habitat in the boreal forests, possibly due to climate change drying out boreal wetlands. Draining of wetlands for development has also contributed to habitat loss.
– **Poor body condition:** Greater scaup have been found to be in poorer body condition over the past few decades, indicating problems with food resources. Reasons may include climate-driven ecosystem changes in breeding and wintering grounds, and increased competition from other diving ducks.
– **Pollution:** Possible negative impacts from heavy metal, agricultural pesticide and oil pollution in wetland habitats. Scaup may ingest pollutants when feeding on mollusks and other invertebrates.
– **Incidental hunting mortality:** Greater scaup are one of the most commonly hunted duck species. Although harvest rates are controlled, accidental shooting deaths in key migration and wintering areas may impact populations.
– **Predation:** Increasing predator populations, such as certain gull species, may be leading to higher losses of eggs and young.
– **Disease:** Avian cholera outbreaks have led to localized greater scaup die-offs in breeding and wintering grounds. Investigations into the impacts of diseases like avian influenza are ongoing.
The specific mechanisms behind the decline are not fully understood and are likely due to a combination of these threats rather than a single factor. More research is needed to determine the relative importance of each of these threats to guide conservation efforts.
Ongoing Conservation Actions
While the greater scaup is not currently endangered, several conservation actions have been taken or are underway to monitor populations and mitigate some of the key threats:
– Annual monitoring of breeding populations across survey areas in Alaska, Canada, and the northern U.S. states. This allows tracking of population trends.
– Collection of body condition, contamination, and disease data from hunter-killed birds to monitor scaup health issues.
– Habitat protection, restoration and management projects (e.g. wetland restoration) are being undertaken in key breeding and migration habitats.
– Regulation of hunting harvests in response to population declines. Limits have been reduced over time.
– Research into impacts of various threats such as pollution, disease, predation, and climate change effects on habitat.
– Public education campaigns to promote wetland conservation and sustainable hunting practices.
– Cooperative efforts between government agencies, indigenous communities, and various conservation organizations to monitor and manage scaup populations across their range.
These actions are aimed at halting further declines and eventually stabilizing populations. However, continued long-term monitoring and adaptive management will be needed to fully understand and address the complex combination of threats facing greater scaup.
Conclusion
In conclusion, the greater scaup has experienced concerning population declines since the 1980s but does not currently qualify as globally endangered according to the IUCN Red List. However, the historical declines and continued decreasing local populations, particularly in certain flyways and wintering grounds, indicate the greater scaup likely warrants continued conservation attention and monitoring. Addressing threats such as habitat loss, pollution, disease, climate change effects, and overhunting will require collaborative research and conservation efforts across the species’ breeding and migration range. If significant declines resume, the greater scaup may warrant listing as threatened or endangered in the future. For now, proactive conservation actions to stabilize populations appear prudent to prevent the species from reaching endangered status.