Fears are growing for a pair of rare peregrine falcons after they failed to return to their skyscraper home to mate this year.
For the last five years, the couple - named Perry and Gwen - have returned every spring to mate on the roof of Quadrant House, next to Sutton station.
But this year there has been no sign of them.
Rob Dolton, leader of a dedicated group of volunteers, whom keep an watchful eye on the protected birds' nest around the clock via a live camera feed, said he fears the worst.
He said: "It could be that they have found a new nesting site, but that is highly unlikely. Peregrines tend to return to the same nest every year and in Sutton Quadrant House gives them the perfect vantage point for hunting, and the nest is protected."
"I think Perry has passed away, I can't see why they would leave here."
Extensive measures have beem taken to protect the birds and their fledglings at Quadrant House, by Sutton station.
It has been made a criminal offence to go on the roof of the building. The birds' eggs have a high value and it is relatively rare for peregrines to nest in urban locations.
Despite recent sightings of one of the birds - the fastest in the animal kingdom at over 200mph - experts confirmed last weekend the nest is not being used by peregrines.
A "gutted" Mr Dolton said: "The London Peregrine Partnership called me after scoping out the site.
"They said they didn't think the nest was being used as it was evident that crows had begun to take over the roof top, and as you all know peregrines hate crows with a passion."
Kath Rayfield left a post on the Sutton Peregrines Facebook site: "I was involved last year with the first rescue of one of these beautiful birds.
"We had nature on our doorstep, let us hope that the new building developments don't scare off the peregrines - forever."
Mr Dolton is hoping some of Perry and Gwen's offspring will return next year.
He said: "Over these last five years the couple have produced 16 chicks, and they know where they have come from.
"I'm sure some will return. It's a great shame as I truly believe we have one of the best volunteer groups in the UK when it comes to looking after these beautiful birds."
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