Published on 23 July 2024
A blueprint for declining habitat specialists: a collaborative project bringing together science, land managers and birders to save Britain’s fastest-declining resident bird.
Daveron Smith – University of Exeter
Ilya Maclean – University of Exeter
Peter Roseveare – Cornwall Bird Watching & Preservation Society
Willow Tits still occupy pockets of wet woodland and scrub in mid-Cornwall, but their range has contracted. Recovery will take more than improving a single reserve. This PhD brings local surveyors, land managers and new ways of mapping habitat and species persistence together to find where birds remain and how we might help them recover.
Britain’s endemic Willow Tit subspecies is in steep decline: a 2020 assessment reported a 94% fall in the UK population since 1970, and around half its breeding range has been lost. Field experience suggested that Willow Tits depend on damp scrub and young woodland with dense cover, and that their reluctance to cross open ground makes both habitat condition and connectivity important. But these assumptions had not been tested at the scale needed to guide conservation action. Developing a framework to do so could also help us understand how best to support other habitat specialists in fragmented landscapes.
The research team, working closely with Cornwall Birds, built a Willow Tit Taskforce and trained volunteers on Goss Moor to survey for the birds using a tailored protocol. Public bodies, charities and businesses opened access across holdings. Their combined effort produced 1,112 surveys and built relationships that now help carry the findings into management.
Above left: Willow Tit Taskforce training on Goss Moor SSSI. Photo: Dave Thomas. Above right: Historic range around 2000 in red; 2024 Taskforce range in green.
Our survey effort shows Willow Tits are now restricted to a smaller range concentrated around the mid-Cornwall moors. Goss Moor and Helman Tor may be sources of birds for the wider landscape if suitable habitat and connections can be secured. To make this a reality we needed to understand what interventions were required and where they would have most impact.
As a habitat specialist, for a Willow Tit, dense, damp young growth differs from tall, dry canopy. While commonly used land-cover mapping may label a large area simply as deciduous woodland. However, collecting field data on the entire landscape is not practical, so satellite and airborne LiDAR data is used alongside field surveys to map vegetation height, woody structure and relative wetness across the landscape as well as other critical habitat quality attributes. This reveals the habitat variation hidden within the broad habitat categories commonly mapped.
Our analysis, showed Willow Tits occurred more often in areas with wet features present and in landscapes with shorter woody vegetation and wetter soils. However, a suitable patch may still be empty if birds cannot reach it.
A parallel analysis uses simulated landscapes to connect habitat suitability with colonisation and local extinction: occupied patches can supply dispersers, while isolated populations can disappear. We explored how, we can use our surveys to reveal broad occupancy patterns and brings population movement into conservation planning. Our real-world willow tit data showed the same pattern: to a much greater extent than habitat amount, connectivity mattered. After accounting for habitat condition and amount, the odds of occurrence were 2.34 times higher for each standard deviation increase in structural connectivity.
Our findings were clear: management interventions should seek to maintain a mosaic of damp young, dense growth while retaining dead wood. Importantly though, we must focus our efforts on examining gaps between patches, including possible linear corridors, prioritising improvements that add to a connected network.
The findings are informing Natural England’s Goss Moor management plans alongside other conservation goals, and the team is assisting other charities and businesses that hold land nearby in developing their management plans. G7 Legacy Funding support has helped put habitat work in place. The Taskforce and land manager partnerships make it possible to coordinate surveys and practical measures across holdings.
Species Recovery Fund support has now been secured for the next three years. Meaning the project is resourced to extend Willow Tit surveys and conservation action across a wider area of Cornwall where populations are known to remain.
The next question for the research team is whether existing funding streams support land managers to deliver the right interventions in the right places. For declining habitat specialists, recovery will depend on funding that enables land managers to translate evidence on where and how to act into targeted action on the ground.
Research behind this story: Mapping Landscape-scale Habitat Quality with Remote Sensing (Smith et al., in review, 2026); Habitat Condition and Structural Connectivity Explain Willow Tit Occurrence Beyond Habitat Amount (Smith et al., in review, 2026); Linking Habitat Suitability and Metapopulation Dynamics to Predict Species Distributions (Smith, Baker & Maclean., in review, 2026).
Image credit: Francis C. Franklin / CC-BY-SA-3.0. Creative Commons License
