Campaigners fear disaster for the endangered songbirds if a plan to build 5,000 homes on a breeding site in Kent is given green light

It is revered for the beauty of its song and is a beloved adornment to the British countryside. But the nightingale – hailed by Keats as a “light-winged Dryad of the trees” – is now in trouble, having suffered a catastrophic drop in numbers in recent years.

Even worse, say ornithologists, the best site in Britain for protecting the songbird – at Lodge Hill in Medway, Kent – is under threat of destruction. Its loss, they say, could deal an irreparable blow to the nightingale in this country. It could also open the floodgates to commercial exploitation of hundreds of other protected environmental sites across the country.

“Lodge Hill is the only Site of Special Scientific Interest (SSSI) in the UK that is specifically set up to protect nightingales,” said Sarah Lee, of the RSPB. “It is the most important site for the birds in the UK. Yet the local council want to build 5,000 homes there. It would absolutely destroy the site and the birds’ homes – and send a very worrying signal about the prospects of protecting other critically important sites in the UK.”

According to ornithologists, the nightingale has suffered a 90% reduction in numbers over the past 40 years. Factors involved in this population crash include the intensification of UK farming that has destroyed swaths of sandy scrubland on which nightingales like to breed, while the spread of human populations in West Africa, where the nightingale spends the winter, has also affected numbers. In 2012, a survey revealed there were only 3,300 breeding pairs left in the UK. The bird is now on the amber list of species of “conservation concern”.

In an attempt to protect the nightingale, the Lodge Hill site – a piece of land once owned by the Ministry of Defence – was named as an SSSI, a place where local species are given special protection against human interference.

However, three years ago, Medway council prepared plans to build 5,000 homes at Lodge Hill, a proposal that was approved by its planning committee in September.

Facebook Twitter Pinterest Lodge Hill, in Medway, Kent, a Site of Special Scientific Interest.

The council, like others around the country, is under intense pressure from the government to build new housing but has only limited amounts of available land. Lodge Hill is the only large site it possesses, the council claims. Hence the planning committee’s decision to allow the building of houses there – even though the land is an SSSI.

“We are eager for this scheme, which is on government-owned land, to progress and deliver the houses and jobs we badly need,” said leader of the Conservative-controlled council Rodney Chambers in 2013, when the proposal was first discussed at council level.

By contrast, wildlife groups and heritage organisations are enraged. “This decision is deeply flawed,” says John Bennett of the Kent Wildlife Trust, which claims that Medway council has failed to demonstrate that the benefits of house building outweighs the destruction of a key SSSI at Lodge Hill.

At the same time, the RSPB claims the council’s proposals contravene government planning policy; Natural England argues that alternative building schemes could deliver a similar number of houses in Medway without touching Lodge Hill; while the National Trust has dismissed a Medway council plan to provide an alternative wildlife site to compensate for the loss of Lodge Hill as unrealistic.

These groups want the Medway council plan to be called in by the secretary of state for communities and local government, Eric Pickles, who would then have to hold a public inquiry. But Pickles – a keen ornithologist – has said he will stand aside from making that decision and has left it instead to Brandon Lewis, the minister of state for housing.

Lewis has still to act, however, and groups such as the National Trust and RSPB are getting nervous. They fear the Lodge Hill plan will be allowed to proceed – with disturbing implications for the UK environment.

“If Medway’s plan for Lodge Hill is allowed to go ahead, the implication for every SSSI in Britain is that the government is not going to step in if any of them are threatened,” said Sarah Lee. “The government would be saying to developers that SSSIs are now fair game.”

In addition to Lodge Hill, 71,000 hectares of MoD land are designated as SSSIs along with 157,000 hectares of Crown Estate land. The Highways Agency, local authorities, Natural England, the Environment Agency and Forest Enterprise also possess significant amounts of SSSIs. All this property – which gives protection to rare plant life, birds, amphibians, and special geological features in Britain – would be vulnerable to being built over if Lodge Hill is allowed to be developed, it is argued.

This point was stressed by Karin Taylor, head of planning for the National Trust, in a letter to the government. Giving go-ahead for the housing project “would threaten the wider environment and wildlife networks in which we have a deep interest in terms of protecting the nation’s special places for ever, for everyone,” she wrote.

Or as Lee said to the Observer last week: “Giving Lodge Hill the go-ahead would be a disaster. It would open the floodgates for uncontrolled development in rare, precious places across the country.”