Alderney Wildlife Trust Drone

Alice Kershaw, Head of Digital Transformation at The Wildlife Trusts, spoke with Dr Tara Cox, AWT’s Lead Terrestrial Ecologist, about how AWT uses drones and thermal drones to survey gannets and seals, particularly in areas that are difficult to access. Read Alice’s article to find out more.

One of the best parts of my role is discovering innovative work happening across the Wildlife Trusts. Recently I spoke with Dr Tara Cox, Lead Terrestrial Ecologist at Alderney Wildlife Trust.

Alderney Wildlife Trust supports ecological monitoring across a nationally and internationally important landscape, including two gannet colonies within the island's Ramsar site, which is managed by The States of Alderney. Historically, monitoring gannet colonies required aircraft surveys and photographers flying over some of Alderney's offshore colonies. Whilst effective, these surveys were logistically difficult and dependent on weather, aircraft availability and volunteer support. The Trust now uses a DJI Mavic 3 Pro drone combined with DroneDeploy software to collect extremely high-resolution imagery of colonies and produce detailed 3D models of nesting sites. The drone flies an automated survey route with around 80% overlap between photographs before carrying out additional orbital flights around the nesting stacks. The resulting images are stitched together to produce both a detailed orthomosaic map and a fully navigable three-dimensional model.

A detailed 3D model of Les Etacs, created using DroneDeploy software from photos collected by a drone.

Bird’s-eye view of Ortac, a gannetry that lies approximately 4.5 km offshore, making it inaccessible for land-based surveys.

This solves a major challenge for seabird monitoring. A simple aerial photograph only captures the top of a stack. Many birds nest on cliffs and vertical faces that cannot easily be seen from above. By building a 3D model, surveyors can count birds from all angles.

The technology is already producing valuable conservation insights. Following significant losses from avian influenza, drone surveys have shown differing recovery trajectories across gannet colonies. One colony has experienced an approximate 30% increase since the outbreak, whilst the larger colony has seen a more modest recovery of around 3%.
Alongside the standard survey drone, the team has also acquired in a DJI Mavic 3T thermal drone. They will still try to continue using manned aircraft surveys alongside the drone, just to make sure that any increases or decreases recorded in population size are a genuine change rather than a result of a change in methods.

Grey seals are notoriously difficult to count accurately. Traditional boat surveys require favourable weather, experienced observers and significant time. Seals are also exceptionally well camouflaged against rocks, making them difficult to spot even when high-quality photographs are available.

During their first thermal drone survey, seals appeared as bright heat signatures against the cooler rocks. Tara described them as "little thermal jelly beans" making counting dramatically quicker and more accurate. The team recorded their highest ever count, identifying 180 animals across the survey area. Just as importantly, the surveys were completed without any observed disturbance to wildlife.

There is often an assumption that only large organisations can deploy advanced technologies. Alderney Wildlife Trust demonstrates that this is simply not true.