Frolicking or fighting? Wildlife officer weighs in on footage of dolphins and swans in a canal

Photo: Brett Plant.

Photo: Brett Plant.

Frolicking?

Fighting?

Protecting their young?

The footage of two dolphins and a family of swans interacting in Mandurah's canals last week has had everybody guessing.

Resident Brett Plant sent through two videos he captured of the splash about, with Mail readers taking to Facebook to make their own suggestions.

"The dolphins are trying to eat the cygnets. The circle of life doesn't care if they are cute," Terry Johnson wrote.

"I think the dolphins are just being inquisitive and the swans are protective of their babies," Kristine Hough wrote.

Department of Biodiversity, Conservation and Attractions wildlife officer Matt Swan has weighed in on the footage, suggesting the dolphins were just up to their usual mischief.

"Those dolphins are just doing their usual thing cruising around the canals, looking for food and playing and having a bit of fun," he said.

"They happened to have stumbled across a pair of swans and their cygnets and the swans, being the very good parents that they are, are quite protective of their little ones.

"So what I see is just two parent swans protecting their cygnets from a perceived threat."

[Dolphins] are very intelligent and with intelligence comes boredom and with boredom comes ratbag behaviour.

Wildlife officer Matt Swan

But rest assured, Mr Swan said a hungry dolphin would have eaten the cygnet if it wanted to.

"We need to remember that as attached as we can be to dolphins and as much as we personify them as beautiful and gentle creatures, they are predators, they are hunters," he said.

"I have no doubt that if they wanted to eat the cygnets, they would've just come up from below and the swans on the surface wouldn't have even known they were coming.

"In this case, they clearly didn't eat them so there's enough fish and food around.

"They are just cheeky dolphins and that's typical dolphin behaviour.

"They are very intelligent and with intelligence comes boredom and with boredom comes ratbag behaviour - they can stir things up just because they want to and just because they can.

"It's absolutely classic."

Mr Swan said he did make a number of other observations about the video, besides the behaviour of both animals.

"I wouldn't say it is unusual but certainly not common that there are cygnets in April. I would normally expect baby birds to be out in Spring," he said.

"That being said, our birds, and particularly our wetland birds, will breed whenever conditions are favourable and we've had a very mild second half of the summer and Mandurah has plenty of shelter.

"It is also a little bit unusual that there are only two cygnets. I would normally expect between five and seven so there's every possibility some eggs haven't hatched or babies have been picked off by predators so these parents are left with two."

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He also noticed one of the dolphins had a partially amputated dorsal fin - an unfortunately common theme among the resident dolphins in Mandurah.

"That's not unusual either and that could've been through predation from a shark or entanglement on a natural debris like seaweed," he said.

"What is likely down in Mandurah is entanglement due to fishing line and we've managed these instances in the past - in fact, we did our first disentanglement of Luca just about one year ago actually.

"We understand that people, when they go fishing, have no intention of catching or entangling a dolphin, but we always encourage people to clean up their fishing line."

To learn more about Mandurah's resident dolphins or keep up to date, follow the Estuary Guardians Mandurah on Facebook.