SACRAMENTO, Calif. — As someone who’s been coming to Mather Lake in Sacramento with family since he was a little boy, avid fisherman Nate Worden said it’s a special place.

“I feel like it’s a bonding time either with the people that you bring and you’re with or just you with nature,” Worden said.

And why he cares about the health of the lake and was surprised to know that the large group of mute swans that inhabit the lake aren’t good for it, experts said, partly because of their large appetite.

“As they’re moving along, they just constantly got their necks down,” Worden said. “Just eating or just eating off the top of the water.”

Mute swans are an invasive species, according to the California Department of Fish and Wildlife, that are native to Europe.

The birds weigh up to 30 pounds with a wingspan of eight feet said avian ecologist at UC Davis Kevin Ringelman.

“So they can eat anywhere between six to 10 pounds of submerged aquatic vegetation a day,” Ringelman said.

Ringelman said that’s less food for native birds and also means murkier water.

“When they clear out the vegetation, it increases the water turbidity and kind of messes with the whole ecosystem function of a lot of our aquatic ecosystems and wetlands,” Ringelman said.

The swans are also quite aggressive.

“If there’s a 30-pound swan that gets aggressive, that’s really quite bothersome,” Ringelman said.

There has also been a recorded death attributed to a mute swan in Illinois in 2012.

Their population in California has recently exploded.

“In the last five years, we’re talking about going from maybe 900 to 1,000 swans to more than 10,000 swans in, you know, three or four years,” Ringelman said.

Which has led to a call to cull the ornate-looking swans, with even legislation calling for landowners to be given rights to dispose of the birds and for hunters to be allowed to shoot them.

Controlling them in this way makes sense, Ringelman said, both ecologically and financially for the state.

Animal Rights Group Friends of Animals said in a post on the actions in California that their environmental impacts are overblown and is against hunting as a method of control.

For Worden, he said he’s seen the swan’s aggressive nature toward his son, while trying to get a closer look at them.

“The next thing you know, he’s running back,” Worden said. “And there’s one running, flapping his, you know, wings at him, hissing at him.”

A lesson well learned he said but overall Worden said he just wants what’s best for the ecosystem of the lake he holds dear.