You’d think that being the longest reigning British monarch comes with enough perks, like celebrating your birthday twice a year and owning a vault of jewels.

There’s also another perk that comes with being Queen Elizabeth II, which is that she is the technical owner of all “unmarked mute swans swimming in open waters” in the UK.

The royal family’s website notes that the British crown has “held the right to claim ownership” of these animals since the 12th century.

These rights were considered valuable and “were subsequently granted by the monarch to many people and organisations as swans were a prized food, served at banquets and feasts”.

As things have changed over the last 800 years, swans are no longer considered a delicacy in Britain, but the Queen still owns all of them.

All 22,000+ mute swans are counted every year by a group headed by the Queen’s official Swan Market in an event known as “Swan Upping”.

“We will lift the whole family out of the water, we will take them ashore, we weigh them, measure them and check them for any injuries,” David Barber, the Queen’s Swan Marker, told Reuters in 2019.

“You have a population of swans that hasn’t changed much since the mid 1800s.”

However, the mute swan population is facing threats from non-native species and dog attacks.

“We've had a pretty rough time with…dog attacks, all sorts of things—like mink,” Barber told the BBC.

“They're not indigenous to this country and they're breeding like mad on the river here, and they do take a lot of young cygnets,” he said. 

Due to COVID-19, this year’s Swan Upping will not be taking place.

“Although not unexpected, it is of course disappointing that members of the public and local schoolchildren will not be able to enjoy Swan Upping this year,” Barber said in a statement.

“It is always a great opportunity for the young people who attend to learn about mute swans, and see first-hand the health checks we carry out on every single family of swans along the river.”

If you’re worried about the welfare of the swans, they’re still being looked after as Swan Upping focuses on conservation and education.

“The Queen’s Swan Marker is working with the Thames Swan Rescue Organisations to continue overseeing swan welfare as usual.

This article originally appeared on Over60.