This article is part of the Feathered Fridays series, a spotlight on different bird species found at your airports or aerodrome spaces.
Image: Sam Lievense
Risk Level: High Risk
Overview
The grey heron is a large bird standing up to 100cm tall with a distinguishable S-shaped neck, long legs, and a long bill. These bills are used to hunt fish, crabs, frogs, and various crustaceans; they are even known to prey on small birds and mammals. They are a multicolored bird with a mostly white head and black nape, blackish-blue streaks down the neck, whiteish grey underparts, and yellow bill/legs/feet.
Grey herons appear similar to their North American cousins, the great blue heron. An easy way to differentiate the two species is simply by observing their range maps: grey herons live predominantly in the eastern hemisphere while great blue herons like predominately in the western hemisphere. Within their own range, purple herons could be confused as a grey heron; purple herons have more colorful rusty-brown streaks running down their neck. Another similar species within their same range is the great-billed heron which can be differentiated by their larger size and more solid dusky grey color.
Range
A common heron species throughout the eastern hemisphere, the grey heron can be found throughout sub-Saharan Africa, Europe, and Asia.
Behaviour
Grey herons are wetland birds found in lakes, rivers, mangroves, canals, and other waterways. During the breading season they become very social birds nesting in high numbers in trees or cliffs near water. Herons tuck their neck back in flight, which can be helpful to differentiate from other similar species like cranes and storks.
Streams, ponds, and bodies of water in large cities can be a deterrent for many wetland birds; however, grey herons have adapted well to the changing urban environments. They have been seen nesting in large numbers in cities such as Amsterdam and Singapore.
Impact on Airfields
Airports should be mindful of animal habitats and habitat management, especially when it comes to larger birds like the grey heron as it could cause serious problems if struck. Standing up to a meter tall, hitting a grey heron can have serious ramifications.
In December of 1997 at London’s Heathrow Airport, a £90m British Airways jet hit a grey heron causing damages beyond repair.
Implementing grass management programs to any airspace area is an effective way to start heron-proofing your airspace. Short grass means less places for the tall herons to hide, nest, and search for food. Examples of grass management can be as simple as filling in an area with gravel instead of grass or regularly cutting the grass near a runway. If your airport is in a wet climate, it can be impossible to manage or drain the waterways around the airport. Grey herons like to perch on fencing near canals or other areas where prey is available. Bird spikes on fences and posts should be implemented to prevent herons and other birds from perching. To prevent the presence of herons in canals, overhead canal netting can be implemented.
More reactive, hands on dispersal methods include long range acoustic devices, stockwhips, pyrotechnics, and lasers. When it comes to stubborn heron species that do not seem to leave a runway, some airports get extra creative and deploy live animals like dogs to scare the birds off.
Identifying which species of heron and birds in general can help determine a species management program and to implement relevant actions that can prevent and reduce wildlife strikes in airports.
“Bird Strike Wrote off £90m BA Jet.” The Guardian, Guardian News and Media, 9 Sept. 1999, https://www.theguardian.com/uk/1999/sep/09/keithharper.
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