The nightjar is one of the most valuable bird species on the ridge. It is a warmth-loving species that thrives on semi-open craggy ridge and in sparser pine forests. The species is a nightbird and is rarely encountered during the day. Even at night, it is rarely seen – they are most commonly observed in silent flight over a path, before quickly disappearing into the dark. Usually the birds remain in the mind only as flashes of white banding on the wings and a white-tipped tail. However, those recognisable features are absent from the female. Nevertheless, the nightjar’s call cannot be forgotten. It’s an ascending and descending whrring can last for a long time. Sometimes loud claps will resonate when the flying nightar flaps its wings together. The nightjar can be heard throughout the Finnish summer into the beginning of August.
It does not build a nest, instead it lays two eggs directly on the ground. Despite that seeming inviting of danger, the perfectly camouflaged bird is is not easy to find and will take wing while standing on its feet. The young are fed with large insects, such as moths and beetles and the species is an effective predator that captures insects in the air. Catching prey is facilitated by its large mouth, which snaps down on insects with skill.
Night flying insects only move on warm nights and in the cold weather period the nightjar could go hungry. However, the species has an exceptional talent in the bird world as it is able to sink into hibernation if cold weather continues and there is resulting lack of food. Its normal body temperature is 41 degrees but can fall close to the ambient temperature of even 10 degrees. Thus it conserves energy and can fast for more than a week. The hibernation is, however, not continuous and the species will wake up when food is in the evening air.
The population on the ridge is very vibrant and there are 3 to 6 pairs plus probably over 20 nesting pairs in the Säkylänharju region – the most important habitat for the species in southwest Finland.
Photo: Arto Juvonen