From Dawn Chorus to Territory Map: A QGIS Breeding Bird Survey Workflow
How Can QGIS Improve Your Breeding Bird Survey Workflow?
Growing up, I remember long days bird recording on the RSPB’s Young Ornithologist Club events, and have recently been trying to improve my aural ID with the Merlin app (more on that later). But my core skills these days are more on the GIS side, so I chatted recently with an exceptional bird surveyor, David Darrell-Lambert (aka BirdbrainUK) to find out how he works. He spoke about consistency, fine timing, and years of hard-won knowledge about which species turn up in which habitats. Our conversation re-shaped how I think about supporting a breeding bird survey with QGIS, QField and Mergin Maps.
In this article I want to explore the breeding bird survey guidance, David’s views, and offer some tips on using the geospatial tech to support the surveys.
Breeding bird survey methodology: guidance, not gospel
If there was one line that stuck with me from my conversation with David it was: guidance is guidance, not gospel. While the Bird Survey Guidelines suggest 6 surveys with at least one in the evening, David, is sceptical of the evening visits, as birds sing for perhaps two hours at dusk; too narrow a window to cover much ground. Better he thinks to be out in the morning when birds sing for an hour before sunrise and four after.
I found it interesting how survey effort and timing flex with professional judgement, species ecology, habitat and location.
Why a breeding bird survey is done by ear
The thing that surprised me most from my chat with David was how aural the survey is; he reckoned 95%+ of records come from song and call, not sight. That changes coverage entirely: your transect is about what you can hear, and hearing range varies:
• around 15 m in dense woodland
• around 50 m in open field
So the route criss-crosses the site to make those ranges overlap and leave no gaps. David moves at a quick but steady pace, mainly so you he doesn’t map the same bird twice as it moves ahead of him. He doesn't double back, and doesn't pause. Bird surveyors sure get some exercise!
Building a QGIS breeding bird survey workflow
This is where the right mapping setup removes avoidable pain, at every stage.
Start with a desk study
A proper desk study tells you what's already been recorded nearby, and helps design your survey approach. Local Environmental Records Centre (LERC) data usually arrives as a spreadsheet of grid references, and the FSC Biological Records Tool, a free QGIS plugin, maps it. The same plug-in can also be used to map NBN Atlas data, as points or grid squares. It's one of several plugins I consider essential; you can find more in my guide to the QGIS plug-ins no UK ecologist should be without.
Plan your transect coverage
In QGIS you can plot your planned transect and buffer by the relevant hearing range; e.g. 15 m through woodland and 50 m across open ground, for an instant check of whether the route covers the site or leaves audible gaps.
A viewshed over a LiDAR terrain model would help justify a vantage point on awkward ground. Incidentally, I explore using LiDAR for survey design further in modernising reptile survey workflows.
Capture field data in QField and Mergin Maps
Going digital in the field is the single biggest workflow upgrade, and if you're still on paper, here's why ecologists should make the switch
Record your actual transect as a GPX track; proof of the route walked.
Use a structured form: BTO species codes, plain-language behaviour labels on screen are far less error-prone with cold hands.
In Qfield you can attach an audio clip to the record point. On an ear-based survey, the actual song becomes evidence, a second opinion, and a training resource; pinned to the exact spot it was heard.
Qfield/Mergin auto-stamp date, time and position, and allow the records from each visit accumulate into one dataset for a full picture.
Map records with standard behavioural notation
The Bird Survey Guidelines set out a standard behavioural notation; singing circled, calling underlined, flight lines for birds passing through. QGIS rule-based symbology can reproduce much of it automatically so the map speaks the visual language a reviewing ecologist already reads.
Note, however, that David cautioned about relying too much on BTO symbology, urging surveyors to consider their audience, whether they would be familiar with the BTO symbols, or whether text acronyms would be easier for them to interpret.
Map bird territories with cluster analysis
David uses a tried and tested approach for mapping territories but our conversation with got me thinking about a little workflow with QGIS functions that might aid interpretation of the bird survey data:
Use the TomBio tools to create separate layers for each bird, then
Run ‘DBSCAN clustering’ to pull candidate territories from the noise; then
Use the ‘Minimum bounding geometry’ to create a polygon around each cluster to turn it into a territory polygon.
The crucial caveat here is that clusters give you territories, not nests. Nevertheless, I’m intrigued how the above would work on your real survey data – give it a go and let me know!
Where AI and bioacoustics reach their limits
AI is everywhere now. But it has limits on bird surveys. Bioacoustic recorders only deliver presence and absence and can't judge distance. And species ID isn’t perfect. For instance, while Merlin, the free Cornell Lab app, is a useful field training aid, and its UK ID pack was built in partnership with the BTO, I’ve heard it can still mix up similar songs, such as Blackcap and Garden Warbler. So it’s definitely not an authority.
However, it’s clear that AI will improve at considerable pace; so let’s see how it supports the surveyor's ear going forward. (As an aside, I take a similarly honest look at AI plant ID in Points, Polygons and Plantlife.)
To Conclude
While a QGIS-based breeding bird survey workflow doesn't replace the surveyor; it does remove the friction.
And in David’s case, using Mergin maps in the field has given him back his afternoons (to power-nap ahead of the next survey!), as he’s no longer digitising data from paper field notes.
Whether the breeding bird survey survey is for development or conservation, a clean, QGIS-native workflow helps you collect data efficiently and accurately. And there are some great cluster functions to explore, and potentially aid your identification of, bird territories.
Ready to streamline your survey season?
If you'd like a pre-built QGIS and Mergin Maps set-up that handles everything from desk study to territory mapping, the Spatialsesh Pro tools are built for exactly this kind of work. We also offer custom-built tools if, like David, you are particular about how you work! Drop me a line for further info: matt@maplango.com.