Technology and innovation lend visibility to heronry survey

With special consent from Natural England, Assistant Warden Mischa Cross explains how specialist equipment was used with careful planning to accurately survey nesting Grey Herons at Pitsford.

In early May 2017, the heronry at Pitsford Reservoir Nature Reserve was surveyed using a drone to see if a more accurate count of nests could be established with this method, rather than counting from on the ground. The trial proved very successful with 14 nests counted from the drone footage, compared with 10 nests counted from the ground.

Aerial footage of Pitsford Water Nature Reserve Heronry using a drone, May 2017. The nests are clearly visible and can easily be counted from the photographs. Young birds can be seen on the nests.

The survey was timed so that the eggs had hatched. This meant adult birds would not be sitting on the nests incubating eggs, as they may be inclined to leave the nest, risking damage or chilling of the eggs. One flight was sufficient to get the required footage and it lasted no longer than 10 minutes. The drone used was a DJI Phantom Vision 2+ v.3, which can fly up to a maximum height of 300ft. For this survey the height was set at 200ft so better quality images could be captured in an attempt to see if egrets were also using the area. It was hoped to get video footage but unfortunately this was unavailable on the day of the survey. The drone was piloted by fully qualified, CAA approved and insured pilot, Josh Hellon. The pilot was always in full manual control of the UAV/drone and it has a failsafe that returns it to the take-off point if there are any problems.

Observations were made from the ground while the drone was in the air to see how the birds in the area reacted to the presence of the drone. No obvious signs of disturbance were witnessed. As the eggs were hatched, the adult birds are likely to have been away from the nest collecting food.

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