Eaton's pintail

Lore & Background

The Eaton's pintail was described by Richard Bowdler Sharpe based on specimens collected by Alfred Edwin Eaton. Sharpe also noted that earlier specimens had been collected during the Ross expedition. Previously considered a subspecies of northern pintail, it is much smaller—one female weighed 450 g versus a mean of 871 g for female northern pintails—and the male is female-like in patterning, unlike the sexually dimorphic northern pintail.

The species breeds from November to March, building its nest in tussock or grass lined with moss and down. Its diet consists mostly of small crustaceans and other invertebrates, but it also forages on seeds and occasionally visits southern elephant seal wallows to feed. The brown skua is a primary predator, especially during the post-breeding molt when the duck is flightless; at that time, Eaton's pintails often shelter in dense vegetation or caves.

An introduction attempt on Île Amsterdam was unsuccessful, with no sightings since 1970. While the population is decreasing, there have been no precipitous drops due to predation from invasive species such as cats and rats, as was once assumed.

Reader's Guide

Eaton's pintail is significant as a restricted-range island endemic, illustrating the vulnerability of isolated island species to introduced predators. Its post-breeding molt, during which it is flightless, makes it especially susceptible to predation by feral cats and brown skuas. The species also demonstrates taxonomic nuance: once considered a subspecies of the northern pintail, it is now recognized as distinct due to its smaller size and lack of sexual dimorphism in plumage. The two subspecies—A. e. eatoni on Kerguelen and A. e. drygalskii on Crozet—highlight microevolutionary divergence within a small geographic range. Despite a decreasing population, the IUCN lists it as Least Concern, as declines have not been as severe as initially feared. Its legacy includes being named after Alfred Edwin Eaton, an English explorer and naturalist, and its presence in the collections of the Ross expedition. The unsuccessful introduction attempt on Île Amsterdam underscores the challenges of establishing new populations.

Did You Know?

• Eaton's pintail is also known as the southern pintail.
• It was named after English explorer and naturalist Alfred Edwin Eaton.
• The species is threatened by feral cats, which prey on it during its post-breeding molt when it cannot fly.
• An introduction attempt on Île Amsterdam failed, with no sightings after 1970.