Another bit of folk-lore about the nightjar is that it gave calves a disease called puckeridge; and on this account country folk still call this innocent but unfortunate bird the puckeridge. The disease, in fact, was caused by an insect which laid eggs on the backs of cattle, whence emerged grubs to cause the skin to pucker. The nightjar may often be seen wheeling about cattle, for the reason, no doubt, that the animals attract insects and disturb moths. Possibly for the same reason the nightjar, instead of flying away from human beings, will flit near about, keeping just in front of a walking man. Among other curious names is "razor-grinder." We met a countryman who only knew the nightjar by this name, derived from the noise made by itinerant razor-grinders at work.
A Ventriloquist
Perched lengthwise on a low branch or rail, the nightjar gives to its churring a ventriloquial effect by turning its head while it croons. Though the crooning is monotonous, it varies in key, loudness, and duration; while the occasional cry, "crow-ic, crow-ic," reminds one of the cry of moorhens and tawny owls. As the bird flies, the snapping of the beak may be heard as a sharp click, whether it is snapped over a moth, or by way of showing resentment at one's presence—young wood-pigeons and doves snap in the same way if disturbed in the nest. The bird has marvellous control of its flight, and has a way of poising itself in the air with the wings meeting above the back, like the wings of the dove in a Scripture-book picture. The serrated claw on the middle toe is probably used for catching prey, and for clearing away fragments that cling round the gaping mouth; while the long bristles that grow from the jaws entangle moths as in a net, as the bird flies with mouth wide open. It finds good hunting among oak-trees, and is especially fond of several of the many insects that chiefly haunt the oaks.
The nightjar is among the nestless birds, and is content to lay its two eggs on the ground. When hatched the young are covered with down like young peewits, and they grow at an amazing rate. An old nightjar, when disturbed from its young, will go through a despairing performance, flitting to a low branch near by, and flapping or wringing its wings in a disconsolate manner, as though to say, "Please go away—please do go away!" The old bird seems to know how helpless is the position of the young ones if once discovered by a foe. But it is never easy to pick out the young birds from their surroundings, while the mother bird on her nest is as good as invisible.
The Cock and the Hen
Not all familiar with partridges know how to distinguish the cocks from the hens by the few minute differences in plumage. In flight the birds are so alike in size that it is impossible to tell them apart—unless, perhaps, they are in pairs, and one goes away ahead of the other on being put up, when the cock may be the hindmost bird. The usual test of sex is the chestnut horseshoe of the breast. The cocks display a fine bright horseshoe badge, while the hens have a few chestnut spots on a whitish ground. However, some insist that this test is not always infallible. One to be trusted absolutely, so far as we know, is the striking difference in the lesser and median wing coverts. In each case there is a light buff stripe down the shaft; but the cock's feathers have a chestnut stain which is lacking in the hen's feathers, while the hen's feathers have zigzag buff cross-bars (of the same hue as the shaft stripe), which are lacking in the cock's feathers. There are other differences which the experienced eye sees at once; and there are differences also in the neck feathers. In the adult cock they are grey, with no shaft stripe; in the hen they are brown, with a light shaft stripe. The age of birds is to be determined to a certain extent quite simply. Those with bright yellow legs are birds of the year. Those with their first pen-feathers rounded are more than a year old, for in the young birds these feathers are pointed at the tip.