Laysan Duck
Laysan duck
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Laysan Duck

Common name: Laysan Duck
Scientific name: Anas laysanensis
Length: 41 cm
Weight: 435 g (1 lb)
Population: approximately 1,000 individuals
Distribution: Midway and Laysan atolls, Northwestern Hawaiian Islands
Issue: reduced and fluctuating population in an extremely limited habitat, invasive species
IUCN Red List status: critically endangered

Description:
The Laysan Duck takes its name from Laysan Island, a small atoll with an area of 4.11 km2 northwest of the main Hawaiian Islands. The earth’s rarest duck, it has mottled, dark reddish brown plumage, orange legs, and a white eye-ring. The wings have iridescent patches. Males and females can be distinguished by their beak colour: yellowish green with black spots for the male, dull orange for the female.

The Laysan Duck has strong wings, allowing it to take off quickly but not to fly long distances. Like other ducks, most of its time is spent dabbling and foraging on land. Its main source of food is the brine flies that proliferate on the beaches and near the central lake on Laysan, but it also feeds on shrimp, insect larvae, moths, seeds, and certain types of algae. To hunt flies, it runs into a swarm with neck outstretched, wings spread, and beak open to catch as many as possible.

Breeding season extends from fall to spring and results in the laying of four eggs on average. By day, these ducks hide in land vegetation; at nightfall, they head toward Lake Laysan, which is three times saltier than the Pacific Ocean. When accompanied by ducklings, they prefer areas of the lake fed by freshwater springs, as the young do not tolerate the lake’s salinity well.

Threats:
Going by DNA analyses of fossilized remains on other islands, the Laysan Duck was common throughout the Hawaiian Islands several hundred years ago. This is no longer the case. In the early 1990s, only 100 adults remained on Laysan, and nowhere else. Droughts, typhoons, disease, over-predation, and invasive species have made the duck highly vulnerable.

On Laysan, the dark days began in 1894, when the German entrepreneur Max Schlemmer moved to the island with his young wife. He introduced a number of animals into this fragile and vulnerable island ecosystem, such as hares, rabbits and guinea pigs. The rabbits quickly took over and caused a number of extinctions, including three bird species, three insect species, and over twenty plant species. After several attempts, the rabbits were finally exterminated in 1923, and since then, the Laysan Duck has teetered on the brink of extinction.

To improve the species’ chances of survival, in 2004–2005, U.S. authorities decided to transfer 42 adult Laysan Ducks to the two tiny islands of Midway Atoll, 620 km northwest of Laysan. After being struck by avian botulism in 2008, the Laysan Ducks on Midway seem to be recovering, and this second population is now estimated at 350 individuals. On Laysan Island, there are approximately 600 adults, so the population trend is on the rise, especially on Midway. However, sustained conservation efforts must continue if the prospects of this rare duck are to improve.

Did you know?
While the population of Laysan Ducks on Laysan Island and Midway now numbers over 1000 individuals, in 1912, only seven adults and five ducklings remained. All of today’s population descends from these few survivors.

REFERENCES: Red List of Threatened Species of the International Union for Conservation of Nature (IUCN) and Encyclopedia of Life.

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