Behind the binoculars - the science and excitement of bird surveys

It was a delight to be out with expert volunteer surveyors, doing Breeding Bird Survey (BBS) at Low Wood Local Nature Reserve in the spring. I recently had the opportunity to learn what happens to the data we had collected when I sat down with Bethany Clarkson (Evidence Officer) and Amelia Lewis (Breeding Bird Surveyor Coordinator Volunteer) from the Trust’s Nature Recovery Data and Evidence Team, to hear about how the data is collected and how its analysis provides real-world insights that are invaluable to reserve managers and informing wider activities for nature’s recovery in Yorkshire.
 

Bethany (in the photo below) has been with the Data and Evidence Nature Reserves Team for 3 years at Yorkshire Wildlife Trust. With a degree in zoology and an MSc in environmental science, she leads the butterfly and breeding bird reserve Trust’s monitoring and evaluation programmes. Bethany explained that she’s supported by enthusiastic volunteers like Amelia.

Amelia has a degree in environmental science and a recently completed MSc in conservation management. She has been volunteering on the BBS for 2 years. Her role includes ensuring site risk assessments are up to date, agreeing survey routes with site managers, coordinating training for new BBS volunteers on a spring day at Barlow Common reserve; and (I think her least favourite part) sending out large numbers of A3 and A4 map blanks to surveyors, then sometimes sending even more maps when they find more birds than expected!

This year, 18 new volunteers joined the project, and Amelia matched them to reserves near where they live. Thanks to this, a brilliant 37 reserves were surveyed by individuals, pairs, or teams. The BBS requires each reserve to be visited six times from late April to early July, recording birds either seen or heard. Amelia explained that while AI tools such as the Merlin bird identification app can be used, surveyors need strong bird knowledge to ensure accurate recording, using the app only to support their observations.

Once the data from each survey is plotted onto a map, different symbols show where a bird was seen, and if applicable whether the bird was calling, nesting, carrying food, or flying. Surveyors then create species maps. Amelia reports that most volunteers are excellent at returning their data, and this year only a couple of sites were still outstanding. She digitises the completed maps onto QGIS, a type of software that allows you to view, edit and analyse geospatial data and then sends the information to David Woodmansey, a volunteer who has been analysing BBS returns for 20 years. 

Bethany explained that the essence of species map analysis is that rings are drawn around clusters of recorded occurrences which appear to represent the activities of a bird or distinct pair of birds. The maps typically show discrete groupings of records indicating the positions held by territorial males on different visits. This clustering analysis can help to provide an insight into the number, distribution and relationship to different habitats of territory-holding birds. The analysis allows valuable, real-world insights, including site-specific reports useful to reserve managers. 

John Preshaw, a Yorkshire Wildlife Trust volunteer who has led the Volunteer Supporter Group at Low Wood Local Nature Reserve for many years, explained how valuable the BBS is for managing the woodland. Enabling him to monitor the wellbeing of the reserve’s bird population. John reports that, even before the analysis is returned, his volunteers usually have a good sense of how the breeding season has gone, thanks to their own observations and the results from nest box cleaning. Once the analysis becomes available, John considers it in light of the three main factors affecting bird wellbeing: food availability (which he explained is rarely an issue in a woodland environment), how the birds have fared over the winter (again something the volunteers cannot influence), and, crucially, nest site availability. Then John and his volunteers support the latter by providing a variety of habitats, including creating glades to offer favourable conditions, and by placing nest boxes throughout the reserve.

The collation of results from 2025 is ongoing, but the results from 2024 reported a total of 64 bird species that held territories on at least one of the sites surveyed, with a number of other species recorded as migrants, visitors or as flyovers. Even for commonly recorded species such as Chiffchaff and Robin, the surveys remain important in understanding the picture of bird populations across the reserves. A small number of records of Red-listed species (those with the highest extinction risk status) such as Cuckoo, Yellowhammer, Curlew and Lapwing were also recorded in 2024, showing the importance of our reserves in providing habitat for some of Yorkshire’s rarest birds.

If you have been inspired to volunteer as a BBS surveyor, do keep your eyes peeled on our volunteer recruitment pages where we advertise BBS Volunteer survey roles in spring each year. Bethany emphasised how hugely grateful the Trust is for the support of both volunteers and staff on the BBS. Amelia added that the best part of her role is meeting volunteers, especially those who return year after year to support the BBS.