Baby beavers have been born in urban London for the first time in 400 years.
A family of Eurasian beavers were introduced to a nature reserve in the borough of Ealing by members of a project promoting bio diversity.
Project leaders said the fact that at least two baby beavers - known as kits - had been born on the Paradise Fields site in Greenford after they set up home.
They said it showed the beavers were "happy" with the habitat.
Dr Sean McCormack, one of the volunteers behind the project, said he was "totally over the moon, thrilled, excited".
He told the BBC: "There's easy fixes to living alongside beavers, we are just afraid of the unknown, we are afraid of change. We haven't lived alongside beavers for 400 years.
"In urban London we are talking about these kits, the first beavers born in urban London for over 400 years. But arguably are these the first kits ever born in urban London?"
He added that he had "a suspicion" that there could be babies at the reserve and when he reviewed footage, he discovered the beavers' offspring.
"It was a real thrill to look at the camera footage and suddenly see this tiny miniature beaver, very very cute, playing with mum on 30 June.
"We have kept it a little bit quiet to settle in and everything. We believe there's two, there could me more but we have seen two together.
"It's testament to the project's success that the beavers are happy enough to breed and continue raise a family here."
Nadya Mirochnitchenko, the ecologist for Ealing Beaver Project said they wanted to prove beavers and people “can live with beavers in harmony" even in an urban environment.
She added: "And this is just a positive message.
"This is an urban site, where people have access to it and the beavers can also thrive as well."
The Ealing project hopes other UK cities and towns will follow their example.
Cities across Europe have been introducing beavers for decades.
Dr McCormack said: "We may need to learn to live alongside them again, and sometimes manage their behaviour, but the ecosystem services they provide have been clearly demonstrated here already at the Ealing Beaver Project.
"Improved water quality, reduced flooding, more insects and other wildlife on site, habitat improvements. And now at least two cute baby beavers to boot."
