About the middle of April, the Pied Wagtail begins to build its nest. This is usually placed in a hole in a bank or hedge, among stones, or in the hollow of a tree; it is composed of dry grass and withered leaves, mixed with moss, and lined with wool, hair, and a few feathers. It is a compact and solid structure, capable of protecting the eggs and young from the damp soil, but is not generally concealed with much art; and hence perhaps it is frequently selected by the Cuckoo, to lay an egg in.
Towards autumn, Pied Wagtails for the most part migrate southwards. In the midland counties they may be often observed in large companies, in October, halting for a few days wherever food is abundant, and then suddenly disappearing; after which only a few stragglers are seen until the spring. They return northwards about the beginning of March. In the extreme south of England they are numerous all the year round; but as many instances have occurred of their alighting on a ship at sea, it is probable that the majority migrate to some southern climate, where the ponds do not freeze and gnats gambol at Christmas.
_Summer_--head and back bluish grey; a pale streak above the eyes; throat black; under parts bright yellow; tail very long. _Winter_--chin and throat whitish, passing into yellow. Length seven inches and three-quarters. Eggs bluish white, speckled with dark grey.
Grey Wagtail is not a very happy name for this bird, as the bright yellow of its neck and breast are far more conspicuous than the more sober grey of the head and back; yet, as there are other claimants for the more appropriate names 'Yellow', and Greyheaded, the young observer must be cautious while reading the descriptions of the several members of the family, or he may possibly fall into error. The Grey Wagtail is among the most elegant and graceful of British birds, and in delicacy of colouring is surpassed by few. Its habits are much the same as those of the Pied Wagtail, but it is even lighter and more active in its movements. It is less frequently observed away from water than that species, and though, like it, not altogether a permanent resident in England, it visits us at the opposite season, coming in autumn, and retiring northwards in spring. It does not seem often to go so far north as Inverness-shire, but is regularly seen about Edinburgh in winter; and, on the other hand, it breeds yearly in the southern counties of England during summer, as on the streams which flow from Dartmoor. This partial migration seems to be characteristic of the family, and is difficult to account for. Why out of a certain number of birds of the same species, some should annually travel southwards, to supply the place of individuals belonging to an allied species, who have travelled yet further to the south, and why, on the reappearance of the latter in spring, the first should return to their northern haunts, are questions more easily asked than answered.