Every year there are several reports of swans being killed by dogs - but it is virtually unheard of for a swan to kill a dog, according to Birdwatch Ireland.

In the aftermath of an incident in Bushy Park on Saturday, in which a dog was killed by a swan, experts have moved to reassure the public that not only are such attacks highly improbable, they only happen when there is a perceived threat to young cygnets.

In the incident at the weekend, a cocker spaniel was swimming in the duck pond in Bushy Park, Terenure near a group of swans and cygnets when an adult swan broke away and attacked the dog, killing it.

“[Swans] are fiercely protective parents and they see a dog as a predator,” explained Niall Hatch of Birdwatch Ireland.

“It’s important that swans are given peace and quiet around the nesting season (which occurs during the summer months).”

In Ireland the most common swan type is the Mute swan, which are largely well accustomed to humans, whom they associate with food. By comparison the migrant Whooper and Bewick’s swans are unlikely to interact.

Male Mutes grow up to 20 kilograms in size, about as large as possible for a flying bird, and they can strike out with their wings. Before doing so, however, they will hiss a warning to steer clear, generally in defence of their cygnets or nests.

Mr Hatch said his organisation receives about four to five reports every summer of swans being killed by dogs but he has never heard of it happening the other way round.

Measured response

Not only are swans a protected species, but it is a criminal offence under the Wildlife Act to interfere with them during the nesting season.

Eric Dempsey, bird expert and author, said a measured response is required to Saturday’s attack - both to alert the public to the fact young cygnets are in the water, and to ward off any extreme reaction.

Although swan attacks, similar to those of seagulls, make headlines when they occur, they are considered extremely rare and are an aspect of natural protective behaviour.

“A swan would see a dog as a perceived threat, as a predator. Any animal will protect their babies,” said Mr Dempsey. Dogs, experts say, should be kept out of the water during the summer months if swans are in the area.

Mr Dempsey stressed the birds are defensive, not aggressive, and will readily lead their young to humans in order to receive food. Any approach to their nest, however, can provoke a response.

A blow from a swan’s wing is similar to getting slapped, said Mr Dempsey, who has himself been on the receiving end while working with the birds.

“There is a myth that swans will break your arm - I have never met or heard of a person who had their arm broken by a swan.”

Attacks are rare, at least in terms of public reporting, but when cases do emerge they capture the public interest and are widely reported.

In 2001, 71-year-old Mary Ryan from Dublin lost her compensation claim against the State when she was beaten to the ground and battered by a swan in the Phoenix Park. She broke her wrist in the incident.

Ms Ryan said that having fed the swan, she heard a fluttering of wings behind her. “When I turned around I couldn’t believe what I was seeing. He was coming for me. He knocked me to the ground,” she said. “He continued to aggressively beat my legs and tried to peck me in the head.”

In a case in the US in 2012, Anthony Hensley (37) drowned in Chicago after being knocked from his kayak by a swan, which then stopped him swimming ashore.

“It [WAS] presumably a male swan and it’s presumably paired, and it’s set up home for the spring,” Chris Perrins, a retired Oxford ornithologist, told the BBC at the time. “It’s going to defend that territory.”

In 2014 there were reports of a swan, subsequently named Asbo, attacking boats and flying directly at humans on the River Cam in Cambridge.

However, despite the potential for such behaviour, Dr Michael Brooke of the University Museum of Zoology, Cambridge said the birds pose “no danger at all” to adult humans.

“I suppose it could be an issue for elderly people or a two-year old, but if you see your child in danger you can just pick them up and walk away,” he said.

“People think of them as intimidating because they have a wide wingspan, but then some people are intimidated by spiders in the bath.”