Two marsh harrier birds at Radipole Lake Nature Reserve in Weymouth have produced what is hoped will be four or five harrier fledglings.
This has not happened in Dorset for almost 50 years and it is a first for West Dorset.
The rare birds of prey are amber listed, which means they are critically endangered.
In the last century marsh harriers have gone extinct twice in the UK and there are now only about 250 pairs in the UK.
The marsh harriers are breeding in Weymouth town centre.
'A dream come true'
Mostly associated with a habitat of reed beds and marshland, marsh harriers have spent the past two or three winters at Radipole Lake in the resort's town centre.
Nick Tomlinson, the site manager of the RSPB Weymouth reserves, explains that it was always hoped the birds would breed.
He says: "It's been a bit of a roller coaster of just sheer excitement and paranoia.
"When the pair started courting there was always the worry that they would move on to another reed bed somewhere else.
"Now that they've stayed it's pretty much a dream come true."
The marsh harriers could stay at Radipole Lake during the winter.
An urban nature retreat
Weymouth town centre might not seem the most likely breeding ground for marsh harriers, but Nick believes that recent onsite renovation work, at the reserve, has helped.
He explains: "For the last few winters the RSPB has been doing a lot of work on the reed beds here to try and improve them for birds like the marsh harrier.
"We've put in about a kilometre and a half of ditches and we've got about six more to do.
"We've created more open water, more edge, more places where there's lots of wildlife and where birds like the harrier - a pinnacle predator - can feed.
"This is the most urban marsh harrier pair in the UK and it's one of only three in the whole of south west England."
Female marsh harriers usually give birth to between two and five young, but without interfering with their nesting ground Nick explains that they are not yet sure exactly how many have hatched in Weymouth.
He says: "By the end of June or early July there should be anything up to six or seven marsh harriers in the air over Radipole, which will be quite an amazing sight to see."
If you want to spot a harrier look out for its pale head and shoulders.
Here to stay?
The marsh harriers seem happy enough in Weymouth for now, but what chance is there of them sticking around come migration season?
Nick says: "Ten or 15 years ago a marsh harrier in winter was almost unheard of, now there's a few sites like ours where they do spend the winter and some of them perhaps start to spend the summer there as well.
"If they do go south for the winter [I hope that] they've enjoyed themselves so much [at Radipole Lake] that they'll come here and breed again."
Spotting a harrier
And if you are in Weymouth and want to spot a marsh harrier, what should you look for?
Nick says: "They're a massive brown bird.
"If you're lucky enough to see the male it's got a pale head and shoulders that make it look like it's got a spotlight [shining on it], particularly in the sunshine.
"Their wings are usually held in a shallow 'v' and sometimes their fingers [the edges of their wings] seem to caress the air as if their feeling their way through it, hunting for their prey.
"They're almost like giant butterflies the way that they fly."