The Goat-sucker

Fri 23rd May, 2014

May is the month when Nightjars return from Africa to breed in the North York Moors. Like all night birds, negative and sometimes sinister folklore has grown up around them.

In Yorkshire they were believed to be the wandering spirits of children who died unbaptised. The Latin name Caprimulgus translates as ‘Goat-sucker’, reflecting a belief from the days when people grazed their goats and sheep on commons that the birds, with their wide gapes, were capable of suckling milk from the animals – and infecting them with disease at the same time.  In fact Nightjars are simply intent on catching the insects which associate with these animals, and their gaping mouths, equipped with bristle-like hairs, almost certainly evolved to assist in this process.

Typical Nightjar habitat in Britain is dry lowland heath with scattered low trees and scrub, forest edges and clearfell. The birds roost by day, perching lengthwise along a low branch or on the ground, their cryptic markings blending in with tree bark, earth and leaf-litter.

Nightjars become active at dusk, the males flying between various perches where they utter their eerie ‘churring’. This song, which has a ventriloquist quality, can continue for up to ten minutes and has been likened to the purr of a sewing machine (or in earlier days, a spinning wheel), mostly at the same pitch but occasionally falling before rising again. Displaying males glide in ‘butterfly flight’ with wings up in a V-shape, clap their wings and fan their tails to show the white spots on their outer primaries and outer tail feathers. They can sometimes be brought closer to an observer by the flap of a white handkerchief, which they may take to be another male displaying in their territory. Females and young males lack these white markings.

No nest is made and the eggs (usually two, and mottled for camouflage) are laid on the ground. The young birds are fed by both parents.

YCN plans to extend some of its summer National Park Safaris into the evening in order to look for Nightjars in the North York Moors National Park. The first of these is planned for 8th June.

Gaynor Chapman