Willow Tit National Survey 2019/20

Today's blog is by Simon Wotton, Senior Conservation Scientist, giving the latest update on the willow tit survey.

Between 1995 and 2018, numbers of Britain's endemic subspecies of willow tit have declined by 82%, making it the second fastest declining UK bird after turtle dove. If considering resident birds only, it is in fact the fastest declining. These plummeting numbers have meant the species is now red-listed in the UK. RSPB and others have researched into the causes of these decline, and have been trialling woodland management solutions for willow tit.

However, due to these declining numbers, monitoring the species is becoming increasingly difficult. Although the UK Breeding Bird Survey, run by the BTO, Joint Nature Conservation Committee and RSPB, is still able to produce an annual trend, the sample size was just 34 squares in 2018.

Collation of willow tit records by the Rare Breeding Birds Panel, since 2010, is increasingly useful, but is currently insufficient to produce robust population estimates, measures of change or current distribution maps: thus, a national survey is needed if our conservation work is going to be properly underpinned by evidence.

Across the range, tetrads have been surveyed following a random stratified design. Survey tetrads were selected, by county, partly based on a stratified random design:  stratum 1) occupied tetrads, from 2007-11 Atlas and later (highest sampling intensity); stratum 2) remaining tetrads in occupied 10km squares, from 2007-11 Atlas and later (stratum 2); stratum 3) the rest of the known (historical) range, from the 1988-91 Bird Atlas. In counties with few recent records, the aim was to cover known and recently occupied sites.

Based on trial work on willow tit responsiveness to playback and detectability, the survey period covered the pre-breeding season, from mid-February to mid-April, with two visits per tetrad during this period. Surveys have been conducted on all suitable habitat within tetrads (2x2 km-squares), using a standardised playback method that has been successfully developed by the RSPB willow tit research project, with a standard recording provided.

An update on survey coverage in 2020

Many thanks to everyone who has taken part in the willow tit survey over the past two years. I have now received records from nearly 1,500 tetrads across the willow tit range, despite the cancellation of fieldwork on 23^rd March this year due to the Covid-19 lockdown. I have summarised coverage by country in the table below:

Surveyed tetrads in 2019 and 2020, by country, from survey data returned by 10^th August 2020. The number of tetrads with Willow Tit records are shown in brackets.

 The map shows coverage so far: the red squares are tetrads where willow tits have been recorded and blue squares where they have not been found. Grey-shaded squares shows tetrads that have been allocated for coverage, but data have either not been entered or returned yet.

Can I request that any 2020 survey data be returned to me now, even if only a single visit was undertaken. I’ll be happy to receive any records by post (although the RSPB headquarters are currently closed, I am still able to collect mail), email, or online via this link here.

Plans for 2021

We are suggesting that the survey should continue in 2021, given the effects of the Covid-19 lockdown this year. Although coverage has exceeded our expectations in most counties, there are still some areas where more coverage would help give us a better idea of overall numbers and range change.

If you are keen to take part in the survey again next year, please get in touch, either by contacting your county bird recorder or myself.

Thanks again for your help with this important national survey.

Continue reading

• Larks descending – but hope is on the rise
• New tricks, old questions. Shedding light on the ecology of the hawfinch
• An all-new, in-depth look into the diet of a familiar face: the blue tit

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