The colonies cover acres of ground with stinking guano, blotting out most of the vegetation that once grew there. Yet penguins are a combative lot, protecting tiny territories whose boundaries are within pecking distance of their nests. In dense colonies, penguins returning from the sea must run a gauntlet of nips and jabs on the way to their nests. Like teens at a prom, courting penguins often follow the rhythms of the group. Penguins generally return to the same colonies year after year, where they seek nest sites and mates.
Males usually return to the colony first, followed shortly after by females.
For the four subtropical and tropical species the Galapagos, jackass, Magellanic, and Humboldt penguins this means returning to underground burrows, cracks, or caves that shelter nesting pairs from the scorching sun and land-based predators. These birds nest at any time of year, depending upon food availability. The fiordland penguin nests under tree roots in coastal rainforests off New Zealand. Recognition is key for a pair's survival and the survival of their offspring. Pair bonds form quickly, and mates recognize each other by wing-flapping, neck raising, and other displays.