The dramatic decline of marsh tits in an ancient Cambridgeshire woodland is a story repeated across the UK as human activity drives species towards extinction

Richard Broughton has been nosing around this neighbourhood for 22 years. He gossips about inhabitants past and present, reeling off information about their relationship status, openness to visitors, brawls and neighbourly disputes. “They used to have a big punch up in spring here,” he says, pointing out where one family’s territory ends and the next begins.

Some areas are eerily quiet, with popular old haunts lying uninhabited. “I always get a bit of a pang now, walking through here and it’s empty. It’s like walking down your local high street and seeing your favourite shops are closed and the pub is boarded up.”

Broughton’s domain is not a city block but an ancient woodland called Monks Wood, in Cambridgeshire. The inhabitants are marsh tits: tiny songbirds, each weighing about the same as two sheets of A4 paper.

Broughton holds up an old Nokia phone and plays a warning call. The bird he’s searching for is a kind of avian Hugh Hefner: nine years old in May and currently hitched up with a one-year-old. He quickly comes to inspect Broughton. Marsh tits are plucky and territorial, with a distinctive black cap and Inspector Clouseau-style moustaches – as soon as they hear the alarm call they race to investigate.

Soon, however, the calls of this family network of birds may only exist in the plastic casing of Broughton’s Nokia. More than 70 million birds have disappeared from the UK’s skies since 1970. The delicate calls of marsh tits – and other songbirds – are becoming harder to find, as populations plummet. The story from this wood is being played out nationally, as human noise gets louder and the sounds of nature vanish.

Broughton, who works at the UK Centre for Ecology and Hydrology, is Britain’s leading expert on these woodlands, and this family of marsh tits has been studied in more detail and for longer than any others in the country. The sound Broughton is playing is the noise of a bird he recorded 20 years ago. During that time he has attached coloured bands to the legs of more than 1,600 marsh tits to identify them. Only 1.7% of those birds are still alive.

The project was set up in 2002 to study the then-thriving population, but they started seriously declining 10 years in. When he started the study there were 22 pairs in this wood. Last year there were fewer than 10. The UK breeding population has declined by 80% in the last 55 years, so these encounters are increasingly rare.

By 2042 the population is projected to be zero. “We know what’s coming. Within my lifetime they will probably disappear. It can be distressing to watch because you get to know their lives and relationships,” says Broughton.

The decline of these birds is a case study in how increasing human activity can drive a species toward extinction. Their dwindling numbers are partly driven by growing competition from blue tits and great tits, which are benefiting from being fed by humans in their gardens (marsh tits wouldn’t venture into people’s gardens for food).

Then there are the declines of insects – a crucial food source. The birds rely on hawthorn-dwelling caterpillars to get in good condition for spring and then feed their freshly hatched young – but climate breakdown now means the hawthorn is coming into leaf long before the birds would normally be nesting.This woodland is a small island of suitable habitat surrounded by intensively farmed arable land. Marsh tits will not fly over open farmland, they only follow hedges and woodlands, so this population is becoming increasingly isolated and incestuous.