The macaroni penguin (Eudyptes chrysolophus) is a distinctive seabird recognized by its prominent yellow-orange crest feathers. These penguins inhabit rocky, water-bound terrains across sub-Antarctic islands and the Antarctic Peninsula, including locations like the Falkland Islands and South Georgia. Averaging about 70 cm in length and 5.5 kg in weight, they are among the larger crested penguin species found across a wide range of islands in the Atlantic and Indian Oceans, extending to the southern tip of South America.
Primary Food Sources
Macaroni penguins are carnivores, primarily consuming marine life and ranking among the largest seabird consumers of marine resources. Their staple food source is krill, particularly the Antarctic krill (Euphausia superba), which can constitute over 90% of their diet during the breeding season. They are estimated to consume millions of tons of krill annually.
Beyond krill, their diet includes small fish, such as myctophids (lanternfish) and marbled rockcod. Small squid and other cephalopods are also consumed, making up about 5% of their diet. Macaroni penguins also eat other crustaceans, like amphipods. They may swallow small stones, which help grind the exoskeletons of crustaceans and provide ballast for diving.
Hunting and Feeding Habits
Macaroni penguins are pursuit predators, using their streamlined bodies and stiffened flippers for efficient swimming and diving. They are active during the day, foraging from dawn to dusk. Their dives are V-shaped, meaning they do not spend time at the seafloor, and rarely exceed two minutes.
These penguins catch prey at depths ranging from 15 to 70 meters, though they have been observed diving as deep as 100 to 115 meters. During a single dive, they can capture between 4 to 16 krill or 40 to 50 amphipods. Foraging trips from their colonies vary in length, from daily excursions during chick-rearing to several days or even weeks at other times. The high energy demands of breeding and chick-rearing necessitate frequent and efficient foraging.
Dietary Shifts and Adaptations
The diet of macaroni penguins varies based on seasonal availability and geographic location. During the breeding season, krill is abundant and forms the vast majority of their food intake. When krill populations fluctuate or become less available, they shift to consuming more fish and squid.
Geographic differences also play a role, as the specific types and proportions of prey vary depending on the sub-Antarctic island or region. For instance, during winter, macaroni penguins from Kerguelen Island have been observed foraging in areas without Antarctic krill, relying instead on other crustaceans. Understanding these dietary patterns is important for conservation efforts, particularly concerning krill fisheries and environmental changes that could impact their food supply.