Blog by Simon Wotton, Senior Conservation Scientist, RSPB Centre for Conservation Science.
Survey background
We’re working with the Rare Breeding Birds Panel (RBBP) and Welsh Ornithological Society to run a national willow tit survey in 2019 and 2020, with support from Natural England, Natural Resources Wales and county bird clubs.
And we’d love you to get involved! Here’s why we’re running the survey…
Our endemic race of willow tit is the second-fastest declining species in the UK, after the turtle dove, making it a red-listed species.
Willow tits are highly sedentary, remaining in an area close to their breeding territory throughout the year. In recent years, they’ve been lost from large areas of southern and eastern England.
© Ian Butler
Why the decline?
Along with others, RSPB have been researching this and have eliminated several potential causes. However, one potential cause that needs further investigation is the effects of deteriorating habitat quality.
In the UK, one of the willow tit’s main habitats is damp young woodland. This habitat is often short lived with sites frequently drying out and developing into mature woodland over 20-30 years. Along with other organisations, including Natural England, we’re currently trialling some woodland management solutions for willow tits. And they’re part of the Back From the Brink HLF project, involving detailed study of daily movements and habitat use as well as habitat management.
However, due to the declining numbers, monitoring is becoming increasingly difficult. While the BTO/JNCC/RSPB UK Breeding Bird Survey is still able to produce an annual trend, the sample had fallen to just 28 squares by 2017.
Although collation of records by the RBBP is useful for the design of future surveys, it is currently insufficient to enable robust population estimates, measures of change or maps of current distribution to be produced: thus a national survey is needed if our conservation work is going to be properly underpinned by evidence.
The aim is to conduct county-level surveys conducted across the known range by willow tit study groups, county bird clubs and other organisations. The survey period will be from mid-February to mid-April, during the pre-breeding season when the birds are territorial, with one or more visits per tetrad (2x2 km) during this period. Surveys are covering all potentially suitable habitat within tetrads, using a standardised playback method. This involves playing a recording with a combination of a willow tit alarm call and song and listening for a response.
Across much of the range in England, survey tetrads were selected, by county, partly based on a stratified random design: 1) non-random, self-selected squares in core areas, mostly around existing monitoring/intervention efforts; 2) random sampling of occupied tetrads, from 2007-11 Atlas and later (stratum 1); 3) random sampling of remaining tetrads in occupied 10km squares, from 2007-11 Atlas and later (stratum 2); 4) lower intensity sampling through the rest of the known range, from the 1988-91 Atlas (stratum 3); 5) in counties with few recent records, the aim is to cover known and recently occupied sites. Data from the 1988-91 and 2007-11 bird atlases, recent county atlases and from the RBBP have been used to identify the areas of sampling intensity.
In 2019, nearly 1,000 tetrads have been surveyed across the Willow Tit range (highlighted on the map), which is very encouraging – many thanks to everyone who has taken part in the survey this year. There are still some areas where we are looking for more coverage, to help give us a better idea of overall numbers and range change.
This map shows the sample survey tetrads in England, Wales and Scotland, highlighting the tetrads that have been surveyed in 2019 (red squares – Willow Tits recorded; blue squares – no Willow Tits).
If you are keen to be involved in this national survey, please contact:
Simon Wotton simon.wotton@rspb.org.uk 01767 693396
or
Paul Bellamy paul.bellamy@rspb.org.uk 01767 693379
For more information on Willow Tits, check the following websites:
https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/willow-tit/
http://backfromthebrink.boldlight-built.co.uk/the-projects/willow-tit/
https://blx1.bto.org/birdtrends/species.jsp?&s=wilti