- The International Penguins Conservation Work Group website reports that about 9 million breeding pairs of macaroni penguins exist in the Antarctic region. The Antarctic Connection site puts that number even higher, at around 12 million. In either case, the macaroni penguin has the largest population of any of the world's species of these flightless birds.
- The colors on the upper parts and the head of a macaroni penguin are a blue-black mix. The under portions of the bird are white. The bird's bill is large and its pinkish base gives way to a red-brown color over the rest of the bill. The macaroni penguin has red eyes and the bird's feet, as well as its legs, are pink. The brilliant colored crests sweep out from the midpoint of the forehead, going to the rear over the eyes. While the female penguins are smaller in overall size than the males, the lengths of these crests are the same. Juvenile birds do not possess the crest feathers until they mature.
- Aquatic life such as squid, crustaceans such as krill and many types of fish comprise the majority of the macaroni penguin diet. The birds do most of their hunting during the day, diving into the water and chasing down their meals. Those that do engage in looking for food at night will not dive as deep as they would in the daytime. Dives as deep as around 200 feet are commonplace for this bird during the day, with most of these dives over in about two minutes.
- The female macaroni penguin reaches her sexual maturity at 5 years old and she can choose a mate at that time. The males require an extra year before reaching breeding age. The larger ratio of males to females allows the girls to be meticulous about which male they select as a mate. Once the female selects a partner, the pair often remains together for life and comes back to the exact same site to breed each year.
- The islands upon which the macaroni penguins breed are crowded with thousands of the birds in summer, but barren in the winter months, with no penguins in sight. The birds establish their nests on the rocky ground and the female lays a pair of eggs in most cases. The initial egg rarely hatches, being much smaller than the first. The penguin parents incubate the eggs in shifts, taking advantage of being away from the nest to feed.