Emperor Penguin

Colonies form on fast ice — the frozen apron welded to the continent — and the timing is unforgiving. The male incubates a single egg on his feet for roughly nine weeks of darkness and wind, fasting the whole time, while huddles of thousands rotate slowly so no bird stays on the windward edge. Chicks must fledge before the ice they were raised on breaks up.

That dependency is the whole conservation story. Fast ice that forms late or breaks early drowns chicks that have not yet grown waterproof plumage, and several colonies have already failed completely in low-ice years. Projections built on current sea-ice trends are severe enough that the species was listed as threatened in the United States in 2022, a decision made almost entirely on the basis of habitat that is seasonal rather than solid.