The Willow Tit is generally regarded as the fastest-declining resident bird species in the U.K., with only the migrant Turtle Dove showing a more rapid fall in population.

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For some years Durham has been regarded as one of the strongholds of the remaining population.

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Over the years 2016 to 2018 extensive studies, led by Steve Evans, In Ordnance Survey square NZ34 (around Houghton-le-Spring) produced results summarised in a January 2019 post on X/Twitter –

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This , and other work, highlighted the habitat choices of Willow Tits, at least in our area, listed in the guidelines for a countywide survey –

 

Habitat

 

In County Durham Willow Tits are not restricted to low lying damp woodlands - in fact they thrive on thin soils on exposed free draining Limestone in dry gorse & thorn copses.

The key habitats to check are likely to be

• Mature thorn copses (Hawthorn, Blackthorn, Elder).

• Successional natural woodland habitats - eg Birchwoods with shrub understorey;

• Natural regeneration on brownfield sites - eg Scots Pine and scrub on former industrial site/pit heaps;

• Woodland edge on larger blocks with successional naturally regenerating edge;

• Larch plantations in the county can hold birds although at a low density;

• Linear sites with successional vegetation & limited canopy tree species - wagonways/some areas of riversides;

• Lowland heaths, such as Waldridge, Bearpark, Pity Me, Greencroft etc;

• Recently established 'community woodlands' - overplanted & regimented planting schemes leading to poor quality young woodlands with a mass of deadwood. These are great for Willow Tits and the population has increased over last decade in these areas​

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The Durham Bird Club Survey (2018)

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The countywide survey took place in 2018 and used a special Willow Tit reporting form as well as the records submitted to the Club via BirdTrack and the Club's Excel spreadsheet. More observations than usual were received in 2018 and 2019 and these results were combined with the data from the Houghton-le-Spring area to produce a county map based on Ordnance Survey 1-km squares

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Clearly no areas were surveyed as intensively as was NZ34 in 2016 to 2018 and one has to assume that the densities shown in NZ34 were not constrained on the ground by the gridlines on the map. The habitats favoured by Willow Tits are often not those which are customarily visited on a regular basis by birdwatchers, so the results are somewhat piecemeal and do not indicate clear wildlife corridors connecting together major concentrations of the species.

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The map shows the species as recorded in 318 1-km squares – just below 10% of the total squares wholly or partly within the county. The records come from the four years 2016 -2019 in the case of NZ34 and from the two years 2018- 2019 for the rest of the county. The species is very largely sedentary, and no attempt has been made to separate breeding season records from those during the remainder of the year, though most records are from the breeding season.

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It has been suggested that there are a number of areas in the county with similar habitat to that in NZ34 and that – if they hold similar densities of breeding Willow Tits – the county population could be as high as 2200 pairs. This is not proven by the data collected; the level of observing and reporting in some of those areas was insufficient to provide comparable data. More generally, extrapolation on the basis of similar habitat does carry risks. There may be subtle differences which are not immediately apparent to the human eye, but which do affect usage by a species. These can include microclimatic factors, presence of competitor and predator species, lack of connectivity to other areas with strong populations of the study species.

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Willow Tit National Survey 2019 - 2020

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The Willow Tit National Survey was led by the RSPB in collaboration with other conservation bodies and made extensive use of recorded playback methods to locate Willow Tits.

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The first year of the National Survey went well, but the 2020 season was badly hampered by Covid restrictions and the survey was extended into 2021, but then cancelled due to the re-imposition of restrictions.

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Before the National Survey data were incorporated, the report Rare breeding birds in the UK in 2020 estimated a  national population for the Willow Tit of 712 maximum total breeding pairs, but noted that “The survey results [for 2019 to 2021] show that the Willow Tit population in Great Britain is estimated at 5,693 breeding pairs {95% confidence limits, 4,847 - 6,265), of which 76% were in England, 21% in Wales and 3% in Scotland. The three most important recording areas across Britain were Yorkshire, Co. Durham and Derbyshire. A full breakdown by county will be available in the paper currently in preparation.” The full national results are still awaited, though a detailed report on the Welsh population appeared in 2022 and quoted 5550 as the estimated U.K. population of breeding pairs. This exceeds the 2000 pair threshold for the Rare Breeding Birds report, so Willow Tit is no longer considered for inclusion in that annual publication.

 

Since the National Survey

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The last few years have seen some concerning developments in the fortunes of this species nationally. The Dearne Valley Nature Improvement Area (NIA) near Barnsley, South Yorkshire was the chosen site for the Willow Tit work in the Back from the Brink programme (2017 to 2021). Like parts of Durham, the Dearne Valley is a post-industrial landscape. However, a paper in the April 2024 issue of the journal British birds documents​​ the decline of this population from 70 breeding territories in 2015 to zero in 2023.

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In Derbyshire a 37% decrease in records obtained between 2022 and 2023  has recently been noted (though differences in observer behaviour between two years can lead to changes in reporting rate).

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Locally it has been noted that a small number of nest sites have been lost to development.

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In 2023, Washington Wetland Centre, which had at least three pairs of Willow Tits, began its Willow Tit conservation project, using colour-ringing to identify and track individual birds. It is also trialling several styles of bespoke Willow Tit nest boxes. Unlike other titmice, Willow Tits normally excavate their own nest holes in rotting tree stumps, so a nest box needs to replicate this situation, e.g. by being filled with wood chips or shavings and by being placed near the ground, to be successful.

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Conservation Considerations

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There is a need for continued vigilance regarding the status of the Willow Tit. The Dearne Valley experience shows the possibility of rapid decline in a well-studied area due to causes which are not yet fully understood.

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We need to establish robust estimates of population numbers and densities throughout County Durham. This is likely to involve observers spending time in areas which they might not necessarily visit and increased reporting of encounters, preferably either via BirdTrack or Durham Bird Club’s Excel spreadsheet. Locations need to be as precise as possible (e.g. Ordnance Survey 6-figure grid reference or GPS or longitude/latitude or What3Words) to enable us to assess whether multiple reports refer to different birds or to the same birds. The special recording form used for the Club’s 2018 survey can also still be used. We also need to hear about any localities in the county where the species used to be regular but has noticeably declined or disappeared during the last few years.

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The habitats preferred by Willow Tits need to be recognised as of conservation importance. Some of these may too easily be dismissed as brownfield or low-grade green belt or “in need of tidying up”. That is not how the Willow Tit sees them – and detailed examination might show that they contain communities of flora, fungi and microfauna which are diverse and different from better-studied and more “visually- attractive” habitats.

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Wildlife corridors between such habitats are also needed to ensure that they do not become isolated pockets. The trackbeds of former railway lines provide some such corridors in parts of the county..

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February 2025

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