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: Mid Risk
Overview
The large-tailed nightjar, Caprimulgus macrurus, is a nocturnal species, meaning they are active during the night as their name suggests. They are masters in camouflage making them hard to spot during the daytime, the large-tailed nightjar could easily be confused as a tree branch or a large leaf on the ground. Because they can be close to impossible to spot during the daytime, most large-tailed nightjar observations are during the night when they are seen flying for insects. Similar nightjar species with a shared range include the savanna nightjar and grey nightjar. The large-tailed nightjar can be differentiated by its white tail spots and rich brown ear patch.
Range
Large-tailed nightjars are found from northern Pakistan, India, and Nepal extending south throughout southeast Asia down to northern Australia. This brownish-grey species is common throughout its range. Nightjar species as a whole are found on every continent besides Antarctica.
Behaviour
Large-tailed nightjars can usually be found roosting or sitting on the ground. Sitting on the open ground allows the nightjars to detect potential predators easier, as they use their notably large eyes to scan a larger area. These nightjars mostly prey on insects. By waiting on the ground until prey is spotted, they can pursuit the flying insects as they pass over their dorsal visual field. Because the large-tailed nightjars prefer open ground close to forested areas, human made environments like parks, golf courses, and airports can attract them. In Malaysia, the large-tailed nightjar is often referred to as the “graveyard nightjar” because it is frequently found swooping for insects in cemeteries.
Impact on Airfields
Unfortunately for the nightjars, their presence in airports results in them being a mid-level strike species. Large-tailed nightjars are attracted to airport runways after rainfall because of the invertebrates that avoid wet soil by coming onto concrete areas and thus increasing their availability. Some scientists theorise that nightjars are attracted to paved ground, like an airport runway, because of the heat it emits during the night. Another attraction to airports is the amount of light produced at night; these lights attract insect species which is what attracts the nightjars. Luckily for airport biologists, the large-tailed nightjar is easily identified by its distractive call; listen for a repetitive, almost car locking type of call.
Airports can try insecticides to reduce the number of insect prey species to limit the number of nightjars on and around the runway. Insecticide usage at the airport has both pros and cons. The main pro of using insecticides is if done successfully, it controls insect species which reduces the number of nightjars and other small birds. When the number of smaller bird species are reduced, their predator species like raptors numbers are also reduced. Having an entire food-web of animal species deterred from an airport can significantly reduce bird strikes. One con of using insecticides is resistance. Insect species that were once controlled by an insecticide can be repeatedly exposed and build up a resistance until finally, they have little or no effect at all. For airports specifically, the type of insecticide can be difficult to manage. Oil based insecticides can risk aircraft from skidding, while water-based chemicals may be washed off in high rain density areas. In high rain density areas, insecticides can mix with water sources through leaching or runoff and can harm aquatic wildlife.
Identifying which species of nightjar and bird in general can help determine a species management program.
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