Stand on the St Kilda breakwater at dusk in July and you might count fifteen or twenty penguins coming ashore over an hour. Drive three hours south-east to Phillip Island on the same night and the number filing up the beach at the Penguin Parade can run into the hundreds. Same species, same general patch of southern Australian coastline, wildly different scale. That gap is the first thing people ask us about when they’ve been to both, and it’s worth actually unpacking rather than just waving at it.
We get this question a lot at the breakwater: “is this the small version of Phillip Island?” Not quite. They’re not really the same kind of thing wearing different price tags. One is a colony that formed by accident inside a rock wall built for shipping purposes. The other is a long-established, actively managed breeding ground on a nature reserve that’s been studied and protected as its primary purpose for decades. Both matter. Neither is a lesser copy of the other.
Two very different origins shape everything else
The St Kilda breakwater was built in 1955 as part of upgrade works to St Kilda Pier, a rubble-stone wall stacked to break waves, not to house wildlife. Little penguins found the gaps between the rocks sometime after and moved in on their own. Nobody designed nesting boxes or curated habitat for them at the outset. That accidental quality is part of what makes the colony remarkable: it’s the only mainland breeding colony of little penguins in Victoria sitting inside a major city, about 7 kilometres from the Melbourne CBD, hemmed in by a working harbour, a busy pier and constant foot traffic.
Phillip Island’s colony sits in a landscape purpose-built around it, with dune systems and boardwalks engineered specifically for penguin movement and viewing. It’s not an accident of infrastructure. It’s the reverse: infrastructure built around an existing natural population. Different starting points, and it shows in how each site now runs.
Size: why the numbers aren’t really comparable
Here’s the honest answer, and I’ll be straight about the limits of it: we don’t publish a precise, current colony-wide population figure for St Kilda as a single confirmed number, because count nights vary with weather, tide, season and how many birds are out foraging versus ashore. What volunteers do instead is run consistent, repeatable count protocols over time so trends are meaningful even when the raw nightly number bounces around.
What we can say plainly is scale. St Kilda is a colony numbered in the tens, sitting inside a rock wall a few hundred metres long. Phillip Island’s is one of the larger, better-studied little penguin populations in the world, numbering in the tens of thousands across a protected reserve with far more nesting habitat available. If you want big numbers and reliable, near-guaranteed sightings on any given night, Phillip Island delivers that at scale. If you want a smaller, quieter, free encounter with a colony that exists purely because penguins decided a rock wall in a city harbour was liveable, that’s St Kilda.
How researchers actually monitor the St Kilda colony
The scientific groundwork here goes back further than most visitors realise. Professor Mike Cullen of Monash University began a long-term study of the colony in 1986, prompted by a harbour redevelopment proposal that raised real questions about what might happen to the birds. He ran fortnightly night trips to the breakwater, assisted by Neil Blake of St Kilda Council, right up until his death in 2001. That fifteen-year run of consistent fortnightly data is genuinely unusual for an urban wildlife population and it set the template for what’s continued since.
Volunteer monitoring has carried on in the decades after Cullen’s death, and it still follows a similar rhythm: population counts, weighing, and banding, done by trained volunteers who know the rock formations and individual nest cavities well enough to check them without pulling birds out unnecessarily. Banding lets researchers track individual birds across seasons, which is how we know things like re-nesting rates and roughly how often young penguins change partners after an unsuccessful first pairing (it’s a meaningful minority, not the majority, but it does happen). None of this requires a big research station. It requires people who show up, fortnightly or monthly, rain or shine, and record what they see.
How Phillip Island’s monitoring differs in practice
Phillip Island’s research operation is bigger in every dimension you’d expect from a larger, longer-funded programme: more staff, more infrastructure, tagging technology, and decades of population modelling built off a much larger sample size. That scale lets researchers there ask questions about broader trends across an entire regional population, foraging range data via tracking devices, and long-run breeding success trends across thousands of nest boxes.
It’s a different research instrument for a different job. St Kilda’s monitoring is closer to a long-running community-science ledger: smaller sample, tightly localised, incredibly detailed at the individual-bird level because the colony is small enough that volunteers get to know specific nesting pairs over years. Phillip Island’s is closer to population-level ecological science at scale. Both approaches are legitimate. I’d argue the St Kilda approach actually produces some of the more human, specific insights, precisely because the colony is small enough for volunteers to notice things like a bird returning to the same cavity for its fourth year running.
Viewing experience: free and unstructured versus ticketed and managed
This is where most people actually feel the difference, more than in any statistic. At St Kilda, there’s no ticket booth, no grandstand, no set show time beyond “dusk”, because penguins forage at sea all day and return to the breakwater after dark, which is exactly why viewing happens then and not during the day. Volunteers are there most viewing nights to guide people, answer questions, and enforce the basics: no flash photography, no torches, dogs on leads and away from the rocks, no climbing out onto the breakwater itself. It’s informal by design, but that informality relies entirely on visitors doing the right thing, because there’s no fence stopping a bad decision.
Phillip Island runs a ticketed, seated, amplified viewing experience with boardwalks and lighting engineered specifically for minimal disturbance to the birds while managing very large nightly visitor numbers. It’s a controlled environment built for scale and consistency. If you want a guaranteed seat and a predictable, managed night out, that structure delivers it. If you want something closer to standing on a working breakwater in the dark with the city skyline visible across the bay and Port Phillip Bay’s actual working harbour humming quietly nearby, St Kilda gives you that instead. We’ve written more on this trade-off in our comparison of free versus ticketed viewing, and it’s worth reading if you’re deciding which to visit first.
Shared threats, different exposure
Despite the size gap, both colonies face a lot of the same real threats: marine plastic and fishing-line entanglement, boat strike, and the disruptive effect of artificial light on birds returning after dark. St Kilda’s exposure to some of these is arguably sharper simply because of geography. The colony sits metres from a working harbour and pier, next to a beach that gets heavy foot traffic and off-leash dogs, whereas Phillip Island’s reserve status gives it more physical separation from daily human activity. Foxes and cats remain a mainland predation risk at both locations, though the fully enclosed, actively managed nature of Phillip Island’s reserve changes the practical risk profile compared to an open rock wall beside a public pier.
None of this makes St Kilda more fragile in some dramatic sense. It just means the margin for error from something like an unleashed dog or a dropped torch beam is thinner on a small urban colony than on a large protected reserve with more birds and more buffer.
Why both are worth caring about
The honest framing, and the one we keep coming back to, is that these aren’t competing attractions. Phillip Island gives researchers a large, well-resourced population to study at scale, and gives visitors a reliable, big-number wildlife spectacle. St Kilda gives Melbourne something rarer: proof that a wild seabird colony can persist, breed and be studied in detail metres from a capital city’s foreshore, entirely because of accident and decades of quiet volunteer effort rather than design.
If you’re planning your first visit, it’s worth reading up beforehand on when to come for the best chance of a sighting and what to bring for a breakwater night visit, since conditions here are less forgiving than a seated grandstand. And if the research side interests you as much as the viewing does, our piece on the volunteer monitoring and banding work at St Kilda goes into how counts and banding actually happen on the ground.
For background on the species itself, and why it has nothing to do with the cold-climate image people sometimes default to, Zoos Victoria and the Australian Museum both publish solid overviews of little penguin biology and conservation status worth reading alongside anything on this site.
