Modernising Reptile Survey Workflows with QGIS, Mergin / Qfield and LiDAR
Introduction
For many UK ecologists, reptile refugia surveys are a familiar but often imperfect process. Despite guidance stretching back to sources such as Froglife’s Advice Sheet 10 (from 1999) there remains a recognised lack of clear, standardised methodology. Survey success depends heavily on experience, judgement, and perhaps most unpredictably the weather.
For me, encounters with reptiles are always very memorable. I remember coming across a small adder hiking in the new forest, and the joy of lifting a tin while testing a survey app with a client to reveal common lizards. Joy!
In this article, I’m going to explore how QGIS, mobile data collection apps, and spatial data, can compliment field expertise to improve reptile surveys.
Pre-survey Site Assessment
Many ecologists still rely on walkovers, and knowledge of suitable habitat based on reptile ecology, to place refugia. While this experience is invaluable, spatial data can significantly improve targeting.
Using QGIS, ecologists can combine habitat data, aerial imagery, and terrain data to identify likely reptile “hotspots” (micro-habitats) both before stepping on site. Habitats favoured by reptiles tend to be sunny, open, undisturbed, well-drained, and frequently south-facing aspect. These characteristics can be derived from data.
Identifying micro-habitats
One of the most powerful but underused datasets is LiDAR. High-resolution terrain models allow ecologists to identify subtle microhabitats that are otherwise easy to miss in the field.
Features such as tumuli, embankments, gullies, woodland edges, scrub interfaces, and even small “sun traps” created by uneven ground can all be mapped in advance. These are precisely the features where reptiles are most likely to bask or shelter. You can also use this as a background layer on your survey app while you are on-site.
Importantly, QGIS can also ensure refugia are distributed appropriately to suit site-specific conditions, to ensure a representative and defensible distribution, and well as a practical distribution (e.g. away from areas of high public use).
A data driven approach not only improves detection rates but also can also help identify potential receptor sites if translocation is required. By using the same habitat suitability logic of sun exposure, structure and connectivity, ecologists can pre-assess a site for it’s capability of supporting a population before any engagement with owners / managers begins.
Repeat Site Visits
Reptile surveys are rarely a one-off exercise. A typical presence/absence survey may involve at least seven visits, while population assessments can require a total of 20 visits under suitable conditions.
Timing, weather and temperature are critical. Weather, temperature and time of day all have a major bearing on survey success. Reptiles are normally most active between 9–18°C in the spring, summer and early autumn, and typically in the morning and late afternoon, but this varies seasonally. Being in the wrong season or in hot, cold, wet or windy conditions can render surveys ineffective.
Consistent surveys
Digital tools provide a clear advantage here. Using QField or Mergin, survey forms can be designed to capture not just species records, but also temperature, cloud cover, wind and time of survey. This creates a consistent dataset that helps interpret results. It also allows subtle patterns such as optimal conditions for a specific area to emerge over time, enabling you to take an evidence driven approach.
Standardised digital forms also help ensure that key information such as weather conditions or survey timing is never missed. Given how influential these factors are embedding reminders or guidance notes directly into the form design can be a simple but effective improvement too.
Re-finding refugia
Accuracy in locating refugia is another common challenge, particularly on repeat visits when vegetation has grown or site conditions have changed (and refugia are obscured by bracken or grass growth). By connecting an external high-accuracy GPS receiver to a survey app via Bluetooth, surveyors can navigate directly back to refugia with far greater precision.
This not only saves time but reduces the risk of missing mats altogether. Mergin and Qfield will capture / store GPS accuracy for reference. And you can append survey results to the same refugia point on each repeat visit, proving that they have been checked during each visit, reducing duplication, and ensuring consistent data collection.
Reporting
Reporting is often where the benefits of a GIS-led workflow become most obvious. When data is collected directly into a GIS-compatible format, QGIS can generate maps of refugia locations, species records, and survey effort almost instantly. This speeds up reporting and communicating results to clients. It also facilitates the mapping of population distributions.
Conclusion
Reptile refugia surveys will always rely on ecological judgement. There is no substitution for professional experience when it comes to knowing when conditions are right or recognising subtle habitat cues on the ground.
However, the integration of QGIS-Mergin/Qfield offers a practical step forward. Identifying micro-habitats using LiDAR, accurately relocating refugia with GPS, and capturing consistent survey data in the field, helps reduce uncertainty and improve efficiency at every stage.
Spatialsesh have a range of resources for ecologists, including pre-built species survey forms, all ready to use in office and field. Plus training videos to support your mapping workflows. If you would like to chat about your particular survey and mapping requirements, give me a shout: matt@maplango.com