Imperial shag

How it lives

Imperial shags nest in colonies on rocky shores and islands, sometimes beside penguins and albatrosses. Pairs are monogamous and both parents brood the eggs. A clutch can hold up to five eggs, and three is the usual number at a colony studied on Deseada Island in Argentina. There the birds arrived in early August, laid eggs from late October, with a peak in the first two weeks of November. About 53 percent of eggs hatched and 60 percent of chicks survived. Another source gives about 28 days of incubation and 75 to 80 days from hatching to flight. Lifespan is not given in the sources I opened.

Where it goes

Mostly sedentary. One source says some birds move north along Atlantic coasts in the austral winter, sometimes as far as Uruguay. On Deseada Island the juveniles and most adults left the colony in late March. I did not find tracking data in the sources I opened.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

IUCN Least Concern (assessed 2018). There is no single reliable global count. Wikipedia notes that most subspecies number more than 10,000 pairs each. A bird-information site lists roughly 340,000 to 1.4 million mature individuals worldwide and says some populations are declining; I could not check this against the Red List page, which blocked access. Eight subspecies are recognised, from the Falkland Islands to Macquarie Island. A 2022 genetic study treats the blue-eyed shag forms of the Southern Ocean as subspecies of one species.