Royal penguins belong to the eudyptid or crested penguins that also include Erect-crested, Fiordland, Macaroni, Rockhopper and Snares penguins. Like in all penguins, males and females look very much alike but males are noticeably larger and have chunkier beaks than females.
Royal penguins are most easily confused with Macaroni penguins because of the similarities in their colourations. While the faces and throats of Macaroni penguins are all black, among the Royal penguins there is a range of colours from all black to all white. Royal penguins are the only penguin with pale gray to white facial colourings. Interestingly, females have more frequently darker faces than males. The colouration of the rest of the body is identical in males and females. The top and back of the head, back are dark bluish-black while the chest, belly are white. The flippers are mainly black but have a thin white trailing edge; their underside is white. The black and white body parts are clearly separated. Long dark yellow and black plumes (superciliary feathers) arise from a patch on the forehead and extend backwards.
The beaks are large and heavy set and dark orange-brown. At the base of the beaks are triangular pink patches of bare skin. The feet and legs are pink but the sole of the feet is black. The irises are reddish-brown.
Juveniles can be distinguished from adults only in their first year when they still lack the long superciliary feathers, which take about 3 years to develop fully. Juveniles are also often smaller than fully grown adults and have a greyish rather than white face and throat.
Royal penguins stand about 65-75 cm tall with both feet on the ground. Their body mass varies throughout the year. At the beginning of their breeding cycle, these penguins weigh usually 4.2 – 7.0 kilogram; males tend to be heavier than females. Post-breeding and prior to the moult they can reach a body mass of more than 8 kilogram.
Like Chinstrap and Adélie penguins, their tail feathers are much longer compared to other penguin species.
This penguin species has a highly restricted breeding range and colonies are found exclusively on Macquarie Island and the nearby Bishop and Clerk Islets.
During the breeding season, Royal penguins forage offshore in waters more than 2000 metres deep and up to 600 kilometres from their colonies. They are most active during day light hours and although capable of diving to more than 100 metres (the deepest dive recorded is 226 metres) they mainly forage at depths of less than 60 metres. They usually perform up to 18 dives per hour and dives last on average about 2.5 minutes.
Royal penguins spend the winter months at sea. They usually return to nesting sites of the previous season from late September to mid-October. Royal penguins also often have the same partner as in the previous season. The breeding colonies vary in size (see below). Many are located along the east and west coasts of the island. But some colonies are located nearly 1.5 km inland and more than 100 m above sea level.
The main land-based predators of Royal penguins are skuas and possibly Southern giant petrels. Until they were eradicated, Wekas (a land bird introduced from New Zealand by the sealers) probably took eggs. Rats also used to take some eggs and introduced cats preyed on chicks. Cats were eliminated from the island and an eradication program targeting rodents is currently underway.
Royal penguins sometimes ingest plastic rubbish floating in the ocean. Plastic pollution can kill the birds. Disturbance caused by people is generally managed by personnel in place. The biggest threats the penguins are facing are changes to their food supply due to climate change.
The seas surrounding Macquarie Island are the foraging ground of Royal penguins. Their breeding colonies are found mainly in the coastal areas around the island but some colonies are located inland. These inland colonies are often connected to the beaches by small creeks that also serve as access path to the colonies. Royal penguins build nests on sandy, level ground but also on rocky substrate when the pebbles are small and on scree slopes.
Royal penguins feed on a variety of prey species that include amphipods (small crustaceans), different species of krill (mainly Euphausia valentini), a variety of fish and squid. The composition of the diet varies with season.
After an intensive courtship period, the females lay two eggs generally from mid-October onwards. The two eggs are laid four to six days apart. As in all crested penguins, the first one is noticeably smaller than the second one (~ 60%). Incubation proper only starts once the second egg is laid. First and second eggs weigh on average 103 and 162 grams and are 69 and 81 millimetres long, respectively. The eggs are incubated for about 35 days and both partners share this duty. However, the females take on the first shift, which can last up to 14 days. The males then take over while the females go to sea. Both parents are usually present when the eggs start hatching around 20 November. All viable eggs tend to have hatched by 10 December.
Most of the first laid eggs do not hatch (up to 95%). If they do, the chicks from the first eggs don’t survive. Thus, Royal penguins rear only one chick per season.
Once the chicks hatch, the males brood them for 10-20 days. During this time, the females make multiple trips to feed their offspring. When the chicks are approximately 3 weeks old, they form crèches while both parents are now out hunting for food. Chicks are fed on average every second to third day until they fledge at the age of about 65 days.