The Little Penguin population on Phillip Island has broken its second record in five months with experts suggesting La Niña is behind the boom.
Phillip Island Nature Parks spotted 5,440 little penguins crossing Penguin Parade Beach within 50 minutes on Saturday.
The previous record, set in May, was 5,219 and was the highest number recorded since counts began in 1968.
Phillip Island Nature Parks research technical officer Paula Wasiak said this year's numbers had shocked her.
"I never thought I'd be seeing over 5,000 penguins," she said.
"If you'd asked me this time last year if we would have 5,000 penguins crossing the beach, I'd say 'no way'."
Ms Wasiak said the spike was likely due to conservation efforts implemented after penguin numbers dropped in the 1980s.
"This is indicating that our research-led conservation work that we're doing, minimising a lot of these particularly terrestrial threats and maximising their habitat is having a great pay-off," she said.
"The penguin population did drop down in the mid-80s, down to 12,000 penguins, which now we have about 40,000 Little Penguins."
La Niña impact
Experts are monitoring the penguins' weights and diets, which are showing an improvement in conditions.
"The chicks are a good weight, that's indicating that food is nice and close to the colony," Ms Wasiak said.
Repeated La Niña weather patterns are thought to be contributing to the swelling population, with penguins' main food source of sardines and anchovies more plentiful during wetter conditions.
"The location of fish is dependent on oceanic conditions like storm activity, so when conditions are ideal, we tend to find fish close to shore and they're easier to catch for the penguins," Ms Wasiak said.
"This year from May we've had a small percentage of penguins doing an autumn breed and that continued until the spring breed so most of this year we've had rebreeding penguins and we contribute that to La Niña.
"We know that in previous years our penguins are more successful in breeding in La Niña years."
