A critically endangered species of bird celebrated for its song could be lost from Wanstead Flats.

That is the stark warning from the Wren Conservation Group, which fears inner London could lose its only population of skylarks.

Gill James from the voluntary organisation explained pairs of skylarks on Wanstead Flats have been unable to breed successfully for years, in part due to disturbance from people and dogs.

The birds' eggs, which are laid in nests among tall grasses, may also be preyed upon by rats, foxes and crows.

Disturbance during the nesting season - which runs from early March to August - can cause pairs to abandon nests with chicks fleeing, getting lost or starving to death.

On the area's remaining population, Gill said: "We are in danger of losing the last few of this critically endangered species. They have already disappeared from Leyton Flats."

The small bird, which is streaky brown with a small crest, is renowned for its display flight.

The RSPB states it is on the Red List of threatened species due to its "recent and dramatic" population declines.

Temporary fencing has been put up by the City of London around the species' main nesting site on Wanstead Flats in a bid to protect the population.

The City of London manages the area of open grassland which forms part of Epping Forest.

Volunteers from the Wren Conservation Group are manning the boundary to answer any questions at the flats. The fence is due to remain until the end of August.

Gill said: "Volunteers have been really impressed by how popular the fencing scheme has been with people who regularly walk on Wanstead Flats.

"The majority of people are pleased to see our special birds being protected and are happy to walk elsewhere during the breeding season."

According to the RSPB, the UK's skylark population halved in the 1990s and is still declining. Numbers dropped 75 per cent in their preferred habitat of farmland between 1972 and 1996.

Wanstead Flats is well known among bird watchers for the range of birds found in its varied habitats.

This is especially the case in the spring and autumn migration seasons, when many birds stop for a rest on their long journeys.