The willow tit, one of Britain’s smallest and most endangered birds, requires a surprisingly large area of wild land to thrive, according to research.
Less than 3,000 pairs of the bird survive, mainly on brownfield sites in former coal mining areas, making it the fastest declining resident species, with numbers plummeting by 94% since 1970.
A study of the birds nesting on a former mining area in north-west England has found that each pair requires seven hectares (17 acres) to prosper. A pair of blue tits typically require less than a hectare.
One reason willow tits may be doing well on former mining sites is because these areas are often quite large but also because such disused or accidentally rewilded land provides the thickets of young trees they require.
Dr Richard Broughton, an ecologist with the UK Centre for Ecology & Hydrology who led the research, said: “The willow tits’ presence in these post-industrial areas is almost a phoenix from the ashes story. They found a refuge, and we should help protect it.
“They like what we tend to think of as quite rubbish woodland, up to 30 years old. That’s their niche because their superpower is they can dig a nest cavity of their own, which gives them the edge in marginal habitats.”
While species such as blue tits and nuthatches require rotten trees where natural holes have formed, the willow tit uses its tiny beak to excavate its own nest-hole. As woodland matures, blue tits and great tits enter and out-compete the smaller willow tit. Willow tit young are also preyed upon by great spotted woodpeckers which drill through the soft wood and devour the chicks like grubs.
Broughton worked with Marta Maziarz from the Polish Academy of Sciences and Wayne Parry, a local citizen scientist, to survey the Wigan Flashes and Amberswood Common, a former mining area in Greater Manchester which is now a mostly protected mix of wetland, woodland, scrub and green space.
More than 30 nests were monitored over three years with the birds caught, ringed and traced so the researchers could calculate their territorial requirements for the journal Bird Study.
Unlike many songbirds that migrate or fly between areas, willow tits “put all their eggs in one basket”, according to Broughton – establishing permanent territories where they live their entire life. The birds don’t like to break from the cover of woodland, leaving them vulnerable to environmental changes.
Broughton called for brownfield former mining areas to be protected, warning that many are earmarked for development, being on urban fringes or having their wildlife value overlooked.
“We used to call them wasteland or ex-industrial and they are prime sites for housing. We need to recognise and protect them for what they are. They’ve had 30 or 40 years of natural regeneration so they are developing into quite nice habitats now.
“Brownfield sites have huge conservation value not just for willow tits, but a broad range of wildlife. It’s important we know their role so that it can be factored into environmental and planning policies.”
