The First Swan Upping of King Charles' Reign Is Underway! All About the 800-Year-Old Royal Tradition

King Charles is continuing a conservation tradition involving local swans.

On Monday, courtiers gave a glimpse into the Swan Upping on the River Thames with a new Instagram video. The week-long census is held each July and started on Monday, marking the first fowl count of King Charles’ reign.

“This year’s Swan Upping is underway on the River Thames,” the clip was captioned on the royal family's social media page. “Once a mostly ceremonial event, it now plays an important role in the conservation of the mute swan. The health of adults and cygnets is assessed by the Royal Swan Marker, and any injuries are treated before the swans are released.”

Though the King, 74, didn’t attend the kickoff (which fell on Queen Camilla’s birthday), Swan Marker David Barber led the Swan Upper squad for a toast in his honor.

RELATED: Swan Upping: Queen Elizabeth's Beloved 800-Year-Old Royal Tradition Returns to the River Thames

While the group’s scarlet, striped and white uniforms may look formal, Swan Upping is a conservation-focused tradition that dates back centuries. It’s a little-known fact that the British sovereign has had the right to own any swan swimming in open waters throughout the United Kingdom since the year 966 AD and the reign of King Edgar “The Peaceful.”

Edgar and many monarchs that followed exercised this right to serve the birds at extravagant feasts, swans are no longer eaten as a protected species. Since the 12th century, an annual Swan Upping census has been held on the River Thames to check the population is being maintained, and Queen Elizabeth focused on a 79-mile stretch from Sunbury-on-Thames to Abingdon.

On Monday, the Swan Upping team hit the water in traditional skiffs featuring flags, pennants, swan hooks, boat hooks and oars carrying King Charles’ cypher (for the first time!) to designate that they're working on behalf of His Majesty.

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Once they come across a family of swans with cygnets, the crew of the lead boat shouts, "All up," and the fleet gently corralled the birds in order to delicately lift them out of the water.

The swans and cygnets then had their feet or wings tied before they were moved onto the riverbank to be weighed, measured and inspected for signs of injury or illness.

"The whole process, as long as there's no serious injury on the swans, takes about 20 minutes," Barber previously told PEOPLE. "All the young cygnets and adult birds have to be released together as the cygnets will get lost otherwise. So you have to be very, very careful. You face the cygnet to the parent bird and then they will go off in the water together.

The adult swans are large — weighing up to 33 lbs. with an 8-foot wingspan — but the practice is well worthwhile.

“It's worth doing because if we didn't, the population of swans would just gradually disappear,” the Swan Marker said. 

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Swan Upping is also educational. The Swan Uppers always make sure to involve as many local school kids as possible in the weighing and measuring so they can learn about conservation, the makeup of the River Thames, and the lifecycle of the swans themselves. And the Uppers have passed on their knowledge to the royal family too!

"The Queen visited swan upping in 2009," Barber told PEOPLE. "She came along and was very interested in all the processes that we were doing. Asked lots of questions. Met lots of children."

Princess Anne also swung by in 2018, and Barber said the Princess Royal was intrigued. 

“She actually went in my rowing skiff and sat next to me as we rowed up the river. She took a lot of interest in it all,” he said.