The emperor goose (Anser canagica) is a rare and distinctive goose species that breeds in Alaska and winters primarily in the Aleutian Islands. With a global population estimated at between 110,000 to 225,000 individuals, the emperor goose is considered a species of Least Concern by the IUCN Red List, but it faces threats from climate change, hunting, and changes to its limited breeding and wintering habitats. In this article, we’ll take an in-depth look at the rarity of the emperor goose including its population numbers, geographic range, breeding and wintering habits, and conservation status.
What is an emperor goose?
The emperor goose is a medium-sized goose species that measures 64–81 cm (25–32 in) in length with a 125–165 cm (49–65 in) wingspan. It has a blue-gray bill and legs, white head, gray back, and black underwings. During the breeding season, the head and back of the neck are stained rusty brown. The emperor goose makes a high-pitched cackling and honking calls.
The species was named for its stately appearance by English naturalist George Edwards in 1761. The emperor goose is called naalaut in the Inuit language.
Where do emperor geese live?
Emperor geese have an extremely limited breeding and wintering range:
Breeding range:
– Coastal western and northern Alaska including the Yukon-Kuskokwim Delta, Seward Peninsula, North Slope tundra, and the Aleutian Islands
Wintering range:
– Aleutian Islands from the eastern Aleutians to the Near Islands
– Pribilof Islands
– Western Alaska Peninsula
During migration, emperor geese stop at Izembek Lagoon and Nelson Lagoon in the Alaska Peninsula. Their entire global range is confined to Alaska and the Aleutian archipelago.
How many emperor geese are there?
Determining the global population of emperor geese is challenging because their remote nesting areas are difficult to survey. Published population estimates range between 110,000 to 225,000 birds:
– The Alaska Shorebird Group estimates the population at 110,000 to 135,000
– The U.S. Fish & Wildlife Service estimate is 150,000 to 200,000
– BirdLife International estimate is 140,000 to 225,000
The emperor goose population experienced significant declines in the 1970s when it was estimated at only 40,000 to 50,000 birds. Conservation measures helped the population recover to stable levels over the past 40 years.
The Alaska breeding population estimate is 80,000 to 100,000 pairs.
On the wintering grounds, peak counts include:
– Alaska Peninsula: 45,000 birds
– Aleutian Islands: 150,000 to 175,000 birds
– Pribilof Islands: 20,000 to 40,000 birds
So while emperor goose numbers have rebounded, the species still has a relatively small global population size confined to a very limited geographic range.
Emperor goose breeding ecology
One reason for the rarity of the emperor goose is that it has specialized breeding habits and habitat needs:
- Nest timing: Emperor geese are early nesters, laying eggs in late May or early June. This allows goslings time to fledge before the first fall storms.
- Nest sites: They nest in wetland basins on the tundra, on islands in rivers, and along coastal lagoons.
- Clutch size: Emperor geese lay 3-6 eggs (average of 4-5).
- Brood rearing: Emperor goslings feed on aquatic invertebrates. Families move to salt marsh habitats after the goslings fledge.
- Breeding lifespan: Emperor geese are long-lived with a breeding lifespan of 10 years or more.
- Breeding fidelity: They show strong breeding site fidelity, returning to the same nesting areas year after year.
Their specialized nesting ecology limits emperor geese to specific remote tundra and coastal sites, keeping the overall breeding population relatively small.
Emperor goose winter ecology
On the wintering grounds, emperor geese are also restricted to a narrow habitat niche:
- Winter diet: Eelgrass and Pacific blue mussels, which they forage on in shallow lagoons and bays.
- Winter sites: Emperor geese are almost entirely restricted to the western and central Aleutian Islands where these food sources are abundant.
- Winter fidelity: They show strong winter site fidelity to the same bays and lagoons.
- Winter behavior: Emperor geese form large flocks of up to 10,000 birds on the wintering grounds.
Their specialized diet and habitat use limits the number of sites that can support wintering emperor geese, keeping the global population relatively small even during winter.
Threats and conservation status
The limited range and small population size of the emperor goose makes it vulnerable to several threats:
Climate change: Rising temperatures are altering nesting tundra habitats and wintering eelgrass beds. Emperor geese showed declines during warm ocean temperature cycles in the 1990s.
Oil development: Proposed oil and gas drilling in the Alaska National Wildlife Refuge and other parts of the breeding grounds poses risks of disturbance, habitat loss, and oil spills.
Hunting: Emperor geese are hunted for subsistence and sport in Alaska. Measures are in place to track harvest numbers to prevent overhunting.
Food web changes: Loss of eelgrass and mollusks in the Aleutians could significantly impact the winter food supply.
Conservation groups have called for greater protections for emperor goose habitats in Alaska. However, their status on the IUCN Red List remains Least Concern near the lower range of the population threshold for threatened status. Continued monitoring is essential to ensure emperor goose numbers remain stable. Their restricted range and small global population makes the emperor goose a rare goose species vulnerable to potential future declines.
How rare is the emperor goose relative to other goose species?
The emperor goose has a much smaller total population and far more limited range than most other goose species worldwide:
Goose species | Global population | Breeding range |
---|---|---|
Emperor Goose | 110,000-225,000 | Coastal western and northern Alaska |
Snow Goose | 6.5 million | Arctic regions of North America |
Ross’s Goose | 1 million | Central Canadian Arctic |
Greater White-fronted Goose | 1.6 million | Across northern North America |
Greylag Goose | 1.5-2 million | Across northern Eurasia |
Canada Goose | 10-20 million | Across North America |
The emperor goose stands out as having a global population 1-2 orders of magnitude lower than most other goose species. Its range is also extremely restricted compared to geese that migrate over continent-spanning routes. Based on population size and geographic distribution, the emperor goose is one of the rarest goose species in the world.
Key facts about the rarity of the emperor goose
In summary, the key facts demonstrating the rarity of the emperor goose include:
- Global population of only 110,000-225,000 individuals
- Entire range limited to Alaska and the Aleutian Islands
- Specialized nesting and wintering habits adapted to rare tundra and lagoon ecosystems
- Population and range much smaller compared to other goose species
- Classified as Least Concern but near threatened threshold
- Faces threats from habitat loss, climate change, and hunting
The emperor goose’s small population, restricted range, and dependence on rare habitats make it one of the more uniquely rare goose species in the world. Continued ecosystem protections will be necessary to ensure the future of this distinctive Arctic-breeding goose.
Conclusion
The emperor goose has a precariously small global population and geographic distribution compared to most other goose species. With specialized breeding and wintering requirements limited to rare coastal tundra and Aleutian habitats, the emperor goose has a challenging future in the face of climate change and habitat loss. Their limited range and small population size relative to other geese demonstrate the emperor goose’s status as a rare and specialized species. Conservation focused on protecting its limited habitats will be key to ensuring emperor goose populations remain stable well into the future. The emperor goose remains one of the rarest geese species on Earth.