British Sea Birds. Charles Dixon
Skuas are birds of remarkably powerful flight, displaying marvellous command over themselves in the air, turning and twisting with great speed. These birds are the Raptors of the sea; a terror to the Gulls and Terns; merciless robbers of the hard-won spoil of more weakly species; destroyers even of the eggs and helpless young of other sea birds. All the four species of northern Skuas are visitors to the British Seas, but only two of them are indigenous to our islands. The first of these to be noticed here is the Great Skua, Stercorarius catarrhactes, one of the most local of British birds during the breeding season, as its only known nesting places in our area are on Unst and Foula, two small islands of the Shetland Group. Except during the breeding season, the Great Skua is mostly oceanic in its habitat, wandering long distances from land in quest of prey, attending vessels and fishing fleets, only drawing landwards by stress of weather or unusual abundance of food. This Skua is practically omnivorous. During its summer sojourn near and on the land it repeatedly raids the colonies of other sea fowl, to prey upon exposed eggs or unguarded young; it captures the smaller Gulls, notably the Kittiwake: it also picks up any stranded fish or other carrion; and is constantly on the watch to chase any Gull or Tern that catches a fish, following the poor bird with fatal persistency until, terror stricken, it disgorges its food, which is promptly seized by the voracious Skua. The call note of this Skua is very similar to that of the Lesser Black-backed Gull, but when under the excitement of chasing other birds, or of seeking to guard its own domain, the bird utters a loud cry which is likened by many observers to the word skua or skui.
The Great Skua resorts to its breeding grounds in April, and the eggs are laid in May. As it returns yearly to the same places, it very possibly pairs for life. The nests are made upon the ground of the high moorlands, amongst the heath and grass, and are mere hollows in the moss, sometimes lined with a little dry grass. The eggs of this Skua are two in number, and vary from pale buff to dark olive-brown in ground colour, sparingly spotted and speckled with dark brown and grayish-brown. These eggs are large in size, and very closely resemble those of the Herring Gull. But one brood is reared in the year, and by the end of August the young birds and their parents desert the nesting colony, and adopt their pelagic habits. Few birds are so courageous in defence of their nests as the Skua. Even such predaceous creatures as Eagles, Ravens, and dogs are driven off; whilst human intruders are screamed at and approached within a few feet, the birds wrathfully extending their legs as if they would strike, and skimming to and fro in rage. Many tales of this bird’s daring at its nesting places are current in Shetland, where it is known almost universally as the “Bonxie.”
Our second species is Richardson’s Skua, the Stercorarius richardsoni of some systematists, the S. crepidatus of others. Although not quite so local as the preceding species, its breeding area is remarkably restricted, so far as the British Islands are concerned. It breeds on the Hebrides, in Caithness and Sutherlandshire, and on the Orkneys and Shetlands. Richardson’s Skua is a more gregarious species than its larger relative, but its habits generally are much the same. It is, for its size, equally daring and rapacious; is also remarkable for its powers of flight; but differs from the Great Skua in being more gregarious. Richardson’s Skua is for the most part a summer migrant to the British Islands, and numbers of birds pass along our coasts in spring to their northern breeding-grounds. It is only during the seasons of passage that the visitor to our southern coasts may hope to fall in with this bird, and even then it does not approach the land much. Like the other Skuas, the present species is a relentless robber of the Gulls and Terns, chasing them up and down until they disgorge their fish, and repeating the process at every opportunity. Eggs, young birds, and carrion, are also eaten. It is said to capture weakly birds, but I do not think it is so much addicted to this Hawk-like habit as the preceding species. During summer insects and ground fruits are eaten, whilst it has been known to take worms and molluscs. The note of this Skua is described either as a plaintive mee or kyow, and when in chase of a bird it has been likened to the syllable yah, oft repeated.
Richardson’s Skua reaches its breeding-grounds in the British Islands early in May. Its haunts at this season are open moors, at no great distance from the sea. Although social at its breeding-places, it can scarcely be described as gregarious, and the nests are usually scattered up and down the moorland area. This Skua appears to pair annually, and the nest, always made upon the ground, is merely a hollow, carelessly lined with a little dry herbage, and sometimes nothing but a shallow cavity in the moss. The eggs, normally, are two, but sometimes three have been found, and occasionally but one. They range from olive to brown in ground colour, spotted and speckled with darker brown and grayish brown. Incubation is performed by the female, and lasts about a month. At its breeding-places Richardson’s Skua is very demonstrative, and often reveals the situation of the nest by its anxious movements above the intruder’s head. After the young are reared the moors are deserted, and for the remainder of the year this Skua is decidedly pelagic in its habits and haunts.
We now pass to the Terns. These pretty graceful birds – widely known as “Sea Swallows” – differ in many respects from the Gulls and Skuas. They most closely resemble the former in general appearance, but may be easily distinguished by their slender form, small size, and forked tail. Of the dozen species that have been regarded as “British,” no less than five breed within the limits of our islands. The Terns are far more locally distributed than the Gulls. Many miles of coast may be traversed without one ever seeing a Tern. They are all migratory birds with us, visiting Britain in summer to breed, and retiring south again in autumn. It is only during the season of passage, therefore, that they are at all widely dispersed, for the remainder of their sojourn on our coasts is spent at or in the near vicinity of their breeding-stations. The five indigenous British species follow.
This fine species – the Sterna cantiaca of Gmelin, and the S. sandvicensis of Latham – is not only the largest of the indigenous British Terns, but one of the rarest. It was formerly much more widely dispersed along our coasts, but persecution has thinned its numbers, and the seaside holiday-maker has banished it from many of its old-time haunts. Special interest attaches to this bird, because it is one of the very few species that have been first made known to science from examples obtained in the British Islands. It was first discovered in 1784, at Sandwich, on the coast of Kent, and described by Latham three years later. Alas! no longer does this beautiful Tern breed in its early haunts on the Kentish coast; it has disappeared from there, as it has from many another locality, without hope of return. The most important breeding-place of this Tern, and certainly the most accessible to the majority of observers, is situated on the famous Farne Islands; even here the bird is much less common than it used to be. There are small colonies on Walney Island, in Cumberland, in the Solway district, on Loch Lomond, in the Firth of Tay, and on the coast of Elgin. Its only known breeding-station in Ireland is in Co. Mayo.
The Sandwich Tern reaches the British coasts in April or early in May. But little is seen of this species whilst on passage, for it evidently keeps some distance from shore as a rule, or passes quickly and unobserved. The smaller Terns, for instance, are commonly seen on the coast of South Devonshire in Spring and Autumn, but I cannot recall a single strong migration of the present species in that locality. This Tern is seldom or never seen at any distance from the sea. Most of its waking time is spent in the air, flying about with easy, graceful motion, in quest of its finny prey. The Sandwich Tern, however, is nothing near so graceful looking on the wing as its smaller relatives, the heavier body, broader wings, and much less acutely forked tail giving it a heavier, more cumbersome appearance. Most of its food is obtained whilst it hovers above the sea. The way in which all the Terns feed is very pretty. They poise and hover above their finny victims, and every now and then dart downwards like a stone into the water and capture a fish, fluttering up again, or remaining for a moment to swallow their capture. A flock of Terns (of any species) fishing is one of the prettiest sights imaginable. In addition to small fish the Sandwich Tern devours crustaceans of various kinds, whilst its young are fed largely upon sand-lice and beetles. The Terns are much cleaner feeders than the Gulls, and I have never known them touch carrion or refuse. I have, however, seen them pounce down upon scraps of food thrown from a vessel. The usual call-note of the Sandwich Tern is a somewhat shrill scream.
This Tern probably pairs for life, and returns regularly every season to its old-accustomed haunts to breed. These are by preference low, rocky, or sandy