Southern rockhopper penguins
Scientific name: Eudyptes chrysocome
Physical description and related species
Southern rockhopper penguins are the smallest of the crested penguins weighing only 2–3.8 kg. They are thus only bigger than little penguins (Eudyptula minor).
Distribution and abundance
Southern rockhopper penguins have a circumpolar distribution. They are found on islands in the region of 46–54˚S. The islands they occupy include Heard Island and the McDonald Islands, as well as Macquarie Island.
Their populations decreased by 34% over the past few decades. Most seriously affected were the colonies at the Falkland/Malvinas Islands. A variety of factors probably contributed to this decrease. Not many new population data exist but it is thought that there are still about 1.2 million pairs.
Conservation status: vulnerable
The population at Macquarie Island is estimated to be 37 500 pairs and may still be decreasing.
The start of the breeding season depends upon where southern rockhopper penguins live and can vary by as much as six weeks. There are also annual variations within the same colony. The females usually lay two eggs within 4–5 days of each other in November. Initially both partners remain at the nest for a few days. Then the males depart and go to sea and only return two to four weeks later. Like in other crested penguins, the first egg is smaller than the second one but the size difference is less compared to other crested penguins. Both eggs may survive and hatch.
The eggs are incubated for 32–34 days. Once the chicks hatch, the male guards the chicks for about three weeks while the female provisions the offspring. Chicks are usually ready to leave the colony in mid-February (depending on when the breeding season started).
Adult penguins have to prepare for their annual moult. If food is plentiful, they moult early. If food is difficult to find, the penguins delay their moult but generally the last birds finish in mid-May.
Diet and feeding
Southern rockhopper penguins hunt a variety of prey but crustaceans and cephalopods appear particularly important. Generally diet composition varies with location and season. On average, southern rockhoppers dive to 20 or 30 metres but a maximal dive depth of 113 metres was recorded in one study.