Blog post by Simon Wotton, Senior Conservation Scientist, RSPB Centre for Conservation Science.
We’re working with the Rare Breeding Birds Panel (RBBP) to run a national willow tit survey in 2019 and 2020, with support from several other organisations and county bird clubs.
And we’d love you to get involved! Here’s why we’re running the survey…
Survey background
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.
Why the decline?
Along with others, we’ve 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.
Prime willow tit habitat at Old Moor RSPB nature reserve, Dearne Valley, South Yorkshire
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.
Survey plans
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.
This map shows the recent distribution of willow tits in Britain, shown by: occupied tetrads from the past from the 2007-11 Bird Atlas and other more recent records (red); remaining tetrads from the occupied 10km squares from the 2007-11 Bird Atlas and other more recent records (blue); ‘historical’ occupied 10km squares from the 1988-91 Bird Atlas (orange).
The plan is to conduct surveys in all 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, a random stratified design will be used, at a tetrad level, of 1) non-random, self-selected squares in core areas, mostly around existing monitoring/intervention efforts, 2) high intensity sampling within core areas, and 3) lower intensity areas through the rest of the known recent range.
Data from the 1988-91 and 2007-11 bird atlases, recent county atlases and from the RBBP are being used to identify the relevant strata. In some counties where willow tit numbers are now considered to be very low, recent known sites will be covered.
How to get involved
If you are keen to be involved in this national survey, please contact: Simon Wotton by emailing simon.wotton@rspb.org.uk or phoning 01767 693396 orPaul Bellamy by emailing paul.bellamy@rspb.org.uk or phoning 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/https://naturebftb.co.uk/the-projects/willow-tit/https://blx1.bto.org/birdtrends/species.jsp?&s=wilti