Young chicks are at much greater risk of predation than adults. Brown skuas (Catharacta lonnbergi) are the main predators of penguin chicks. Skuas mainly feed on the chicks and eggs found along the edge of the population which are perceived as weak and solitary. The formation of chick crèches act as an anti-predator-defense. Skuas are less likely to attack the crèches of gentoo chicks because it is hard to distinguish where one chick is within a group.
In the water, waddell seals (Leptonychotes weddellii) have been seen feeding on gentoos. Leopard seals (Hydrurga leptonyx) will travel in the gentoo breeding grounds and attack penguins leaving and returning to the colony. They are most often seen eating chicks as they first enter the water during fledging. Other species of seals such as fur seals from the genus Arctocephalus and southern sea-lions from the genus Otaria have been observed eating gentoos, although their impact on the population is unknown.
The main adaptation to evade predators is countershading. Aquatic predators can look down and see the black dorsal side of the gentoo, which blends in with the ocean floor. Likewise, seals looking up see the white ventral side, which blends in with the light from the sky.
- Brown skuas (Catharacta lonnberg)
- Waddell seals (Leptonychotes weddellii)
- Leopard seals (Hydrurga leptonyx)
- Fur seals (Arctocephalus)
- Southern sea-lions (Otaria)
Anti-predator Adaptations: cryptic