One ‘absolutely prolific’ male bird is keeping his species alive in the U.K.

Conservationists have long been working to keep a rare species of bird from disappearing entirely from the United Kingdom. 

But any recent success they’ve had in protecting the Montagu’s harrier’s British population can largely be attributed to the mating prowess of one “absolutely prolific” male, says conservationist Mark Thomas.

The 10-year-old stud in question is called AU — the chemical symbol for gold — and he’s sired 16 juveniles over the course of his life, including 10 in the last two years.

“He’s at the top of his game,” Thomas, the species lead for Royal Society for the Protection of Birds (RSPB), told As It Happens guest host Paul Hunter. 

“He is single-handedly propping up this species in the U.K. There’s no two ways about it.”

‘It’s been a great year’

Montagu’s harriers are migratory birds of prey who spend their winters in Africa and parts of Asia, and return to Europe every spring to breed.

Globally, their population is on the decline, and listed as a species of least concern on the International Union for Conservation of Nature’s Red List.

In the U.K., the RSPB says, the already rare birds have been rapidly declining, and threatening to disappear from the country altogether. 

At their peak in the 1950s, there were about 30 breeding pairs in the U.K., which dropped to zero in the ’70s, before rising back to 13 in the mid-aughts. That was followed by another steep decline when there were zero breeding pairs reported between 2000 and 2003. 

“We’re desperate to try and save the birds we have currently,” Thomas said. “And it’s been a great year.”

That’s thanks to AU. 

After successfully raising four chicks in 2025, the so-called “golden boy” returned again this year to do his acrobatic mating displays in the hopes of catching the eye of some willing females.

“He’ll fly to, like, a thousand feet in the air and then he’ll do these amazing twist and turns flashing his wings,” Thomas said. “The females will then appear. They will chase him around.”

This year, Thomas said, three females were fighting for AU’s attention. 

“The three had a big fight, and they got down to two. And then the two stayed, and nested with him.”

Protecting the nests 

AU fathered six chicks between his two mates, four female and two male. 

Conservationists are hopeful that his sons will one day return to the U.K. to breed. Two of his male offspring from 2025 have already been spotted in the country, though they’re not yet old enough to breed.

“That’s really good new in terms of the population continuing,” Thomas said.

The six new hatchlings are spread evenly among two nests, roughly one kilometre apart in a top-secret location, somewhere on a British farm.

Only the scientists and the landowners know where the nests are located, and the researchers constructed barriers around them to protect the baby birds from predators and other threats. 

“This is one of the most exciting birds we have in the U.K. and to work on it is a dream every single day,” Thomas said. 

“It’s also quite a lot of responsibility as well, you know, to know that you are handling the chicks of a bird that has only got two nests in the whole United Kingdom.”

Montagu’s harriers are a lowland species that prefer to nest in marshes and river plains. When no suitable habitat is available, they tend to nest instead among the crops on farmland, putting them at risk of being destroyed by agricultural machinery.

“So the RSPB’s role is to find these nests, liaise with the farmers, work very closely with them and then safeguard the chicks in their nest,” Thomas said.

Tracking the youngsters

That should be easier in the future, if all goes according to plan. 

For the first time, the RSPB has attached satellite trackers to two juvenile harriers, one from each nest.

The young birds will soon be ready to leave their nest and migrate, and the RSPB will be able to see exactly where they go, and where they end up should they return. 

If they survive and return to the U.K. to breed, Thomas and his team should easily be able to find their nests and spring into action once again. 

“We’ve never done this with juveniles before,” he said. “So we’re absolutely kind of, you know, on tenterhooks waiting to see what the data shows.”