More than a quarter of Bournemouth, Christchurch and Poole's important nature sites are not being conserved, figures reveal.

Despite a government pledge to strengthen protection of biodiversity, experts warn consistent underfunding has left councils struggling to protect their natural assets.

There are more than 40,000 so-called Local Sites in England, which the Department of Environment, Food and Rural Affairs defines as places with a "substantive nature conservation importance", because of the wildlife or geology they are home to.

Bournemouth, Christchurch and Poole boasted 53 such sites in 2018-19, the most recent Defra figures show.

Of these, just 39 (74 per cent) were in "positive conservation management", which means the council can prove measures are in place to conserve the environment.

Local Sites are different to Sites of Specific Scientific Interest – although Defra says many are their "equal in quality" – and councils do not have a legal duty to protect them.

However, government guidance says they should take the lead in partnering with local organisations to manage them, and must provide figures to Defra’s annual monitoring report.

Only 47 per cent of Local Sites across England are being conserved, according to the 2018-19 report.

But of the 149 councils asked to provide data, 62 (42%) failed to do so, with 48 of those having failed to respond for at least the last three years.

The report notes many local authorities say they have insufficient resources to carry out assessments of their sites.

Experts say years of cuts have seen funding diverted from discretionary services such as conservation, towards obligatory areas like social care.

David Lowe, head of ecology at Warwickshire County Council and a member of the Chartered Institute of Ecology and Environmental Management, said this meant some areas are inevitably "put on the back burner", and that "ecology has been one of these for many years."

Ministry of Housing, Communities, and Local Government figures show English councils' environmental initiatives budgets – which includes grants for third-party groups, individual environmental projects, and environmental education – took a nine per cent hit between 2014-15 and 2019-20, falling from £59 million to £53 million.

The Government’s recent Environment Bill pledges to "strengthen the duty on public authorities to enhance biodiversity".

But Jason Reeves, head of policy and communications at the CIEEM, said it was "fantasy to think that it can be delivered without extra resourcing".

David Renard, environment spokesman for the Local Government Association, said any new burdens placed on councils "must be properly resourced", following significant budget cuts and increasing pressure in areas such as social care.

A Defra spokeswoman: “Our Environment Bill sets out how we will protect our precious species and ecosystems, and local authorities have an essential role to play.

“We will work with them to deliver these measures and ensure any new costs are fully assessed and funded.”