The St Kilda little penguin colony runs on a surprisingly predictable annual calendar. Once you know the four main phases of the year — breeding, chick-rearing, the pre-moult fattening period and the moult itself — almost every observation you make from the breakwater falls into place. This page walks through the full seasonal cycle as it plays out on the rocks each year, so visitors and new volunteers can know what to look for at any given time.
Late Winter to Spring: Courtship and Egg Laying
From around late July through October the colony enters its most vocal period. Pairs re-form at the mouths of the rock cavities that they used the year before, and courting birds can be heard calling to each other well before sunset. Little penguins are usually monogamous from season to season, and they return to the same nest site for years on end unless the cavity collapses or is taken over.
Eggs are typically laid between August and early November. The normal clutch is two eggs, laid a few days apart, and both parents take turns incubating through roughly five weeks of sitting. During this period you can occasionally see individual birds crossing the path on their own to swap shifts — one of the few times an adult will be out of the water in daylight.
Strong winds, heatwaves and unexpected rain can all cause eggs to fail in an urban colony, which is one reason researchers weigh and band as many birds as they can before the breeding season begins. A healthy parent going into incubation is a much stronger predictor of chick survival than any amount of post-hoc intervention.
Spring and Early Summer: Chick Rearing
Chicks hatch from September through December and are fed almost entirely on fish that the adults have chased, caught and swallowed whole earlier that same night. The parents regurgitate into the chicks’ beaks, which is why returning adults can look so much heavier coming in than they did going out. A growing chick needs enormous amounts of food, and a pair of adults will often bring in twenty or more fish a night between them during the peak of growth.
The guarding phase lasts about two to three weeks after hatching, during which one parent stays with the chicks while the other feeds. After that the chicks are large enough to be left alone in the nest and both adults can go out to fish at the same time. This is when colony activity at the water’s edge really peaks — dozens of birds coming ashore within the same short window after sunset.
Chicks fledge at roughly eight to ten weeks old, usually in January or February, and leave the colony to teach themselves to fish. Most of them do not return for their first year of life, and those that do survive that first winter come back the following breeding season as new recruits to the colony.
Late Summer: Pre-Moult Fattening
After the chicks have fledged, the adults enter one of the most physically demanding periods of the year. They have a few weeks of intensive feeding to build up enough body fat to survive the upcoming moult, during which they cannot enter the water at all. Adults may put on twenty to thirty percent of their body weight in this short window. This is also when researchers see some of the widest foraging ranges of the year, as birds push further into Port Phillip Bay and sometimes out into Bass Strait to feed.
Visitors to the breakwater in February and early March often wonder why they are seeing fewer birds than they expected. This is the reason — the adults are offshore, away from the colony, working hard to put on the weight they will soon need.
Autumn: The Moult
The moult is the most visible stage of the calendar for an attentive visitor. Little penguins do not moult a few feathers at a time the way most birds do. Instead they undergo a single annual “catastrophic” moult, during which they stay on land for two to three continuous weeks and replace every feather on their body at once. They cannot swim during this period because the new feathers coming through have not yet sealed together into a waterproof coat, and an adult that tried to enter the water mid-moult would lose body heat within minutes.
Moulting birds are usually seen tucked into nest cavities or in sheltered gaps in the rocks, looking almost comically unkempt — clumps of old feathers stuck to the body, new blue-grey plumage pushing through beneath. They often look thin and bedraggled by the end of the moult, because they lose around half their body weight while they cannot feed.
The moult typically happens between late February and April. It is the single most stressful event in a little penguin’s year, and a bird that has not built up enough body fat in the pre-moult fattening period will sometimes die during this phase. This is why healthy fisheries in Port Phillip Bay matter so much for the St Kilda colony: the birds need to be in peak condition before they start.
Winter: Recovery and Return to the Colony
Through May, June and July the colony is in its quietest phase. Most adult birds have finished the moult and are back at sea rebuilding the reserves they spent earlier in the autumn. Activity at the breakwater is at its lowest of the year. You will still see small numbers of birds coming ashore, but the dense post-fishing waves that visitors see during chick-rearing season simply do not happen in winter.
By late July the cycle begins again. Pairs re-form, calling resumes, and the first eggs of the new season are usually laid within a few weeks.
What This Means for Visitors
If you want to see the highest numbers of penguins coming ashore at sunset, plan your visit for spring or early summer (roughly October to December), when both parents are shuttling food to growing chicks. If you want to see moulting adults up close and experience one of the more unusual stages of the annual cycle, visit in March. If you are happy with a quieter, more contemplative visit, winter is still rewarding — you will see fewer birds but you will also share the boardwalk with fewer people.
Across every season, three rules apply: no flash photography, no climbing on the rocks, and stay at least three metres from any penguin. The colony only exists in its current form because visitors have followed those rules for decades, and it will continue to exist only as long as people keep following them.
