BIRD'S NEST BIRKENIIEAD 657 chosen sites of other birds, but build their own nests and rear their own young, are less clearly defined, because they are not uniformly para- sitic in their habits. Of this latter class, the house sparrow of Europe as often makes its own nest as it seizes upon that of another species. Nearly or quite all of this class, usually marked as parasites, are so only occa- sionally, and by force of circumstances. The true members of the group are not many, and, so far as is at present known, are confined to the two genera cuculus, or true cuckoos, and molothrus, or cow birds. According to Mr. A. R. Wallace, birds' nests may be divided into two classes: those which are exposed or im- perfectly concealed, and those which are cov- ered, or so placed that the sitting bird is ef- fectually hidden. Birds may also be divided into two groups, according to the difference of coloration in the sexes : in some species varied and brilliant colors occur in both sexes; in others, a more numerous class, the male is brighter than the female. With but few ex- ceptions, Mr. Wallace finds that birds of con- spicuous color build concealed nests, while in species where the female is dull the nest is fully exposed. Among American birds in which the females are bright and conspicuous, and which accordingly conceal their nests, or make them of a color to deceive, or of a form or depth to hide the sitting bird, are: the kingfisher, woodpecker, Carolina parrot, Bal- timore oriole, humming birds, magpie, many bright warblers, sparrows, and finches, meadow lark, Zenaida dove, wild turkey, quail, Canada, pennated, and willow grouse, and summer duck. Among our birds in which both sexes are dull, and a concealed nest unnecessary, are the thrushes and orioles, and the passenger pigeon. Among those in which the male is bright and the female dull are the yellow- breasted warbler, goldfinch, grossbeaks, scarlet tanager, redstart, bobolink, red-winged black- bird, kingbird, many flycatchers, and the ruffed grouse. Another interesting coincidence is that in the concealed or concealing nests, the eggs, as a general rule, are white, as with the owls, swallows, kingfishers, woodpeckers, hum- ming birds, quails, and doves. See " Pro- ceedings of the British Association for the Ad- vancement of Science," for 1867, and "Pro- ceedings of the Boston Society of Natural His- tory," vol. xi., pp. 319-321, 1867. (For the systematic classification of birds, and the his- tory of the science, see ORNITHOLOGY.) BIRD'S NEST, Edible, the nest of the sea swal- low of the Malay archipelago, called lawit in Java and salanyane in the Philippines (hirundo esculenta). The bird is uniformly dark-colored, inclining to green on the back and blue on the breast, has a short, strong bill, broad at the base, and is a little smaller than our swallow martin. It gathers from the coral rocks of the sea a glutinous weed or marine fucus, which it swallows and afterward disgorges, and then applies this vomit with its plastic bill to the sides of deep caverns, both inland and on the seacoast, to form its nest. When complete the nest is a hollow hemisphere, of the dimensions of an ordinary coffee cup. When fresh made it is of waxy whiteness, and is then esteemed most valuable ; of second quality, when the bird has laid her eggs ; and of third, when the young are fledged and flown. The lavvit fre- quents mostly the deep, surf-beaten caves of thelB. coast of Java, principally those of Karang Bollong (hollow reefs), in the province of Bag- len. These caves open at the base of a per- pendicular face of rock, nearly 500 ft. high, the mouths being from 18 to 25 ft. in breadth and 30 ft. in height ; within they continue to expand, until they attain the dimensions of from 100 to 120 ft. in width and 450 ft. in height, and for many hundred feet within the waves break with terrific fury. The collectors of the nests are lowered over fearful chasms, and move along a slippery foothold, at the risk of instant destruction. The collections take place in April, August, and December. These nests are also obtained in other parts of Java, and the islands eastward, on the coasts of Borneo, and in the limestone caves of the Philippines. The whole product of Java and Netherlands India, which is a government mo- nopoly, is 40,000 or 50,000 pounds annually, worth from $5 to $35 a pound ; some of the finer sorts sell in Chinese markets for twice their weight in silver. It is well known that the edible nest is a whimsical culinary fancy of the Chinese alone ; they use it in the prepa- ration of their most refined soups. Alone it has an insipid glutinous taste. The Chinese attribute to it peculiar strengthening qualities; but this sensual people chiefly prize it for its alleged properties as an aphrodisiac. BIRK.ENFELD, an outlying principality be- longing to the grand duchy of Oldenburg, Ger- many, surrounded by the Rhenish Prussian districts of Treves and Coblentz; area, 194 sq. in. ; pop. in 1871, 36,128, of whom 7,300 were Roman Catholics. The soil is poor, though well cultivated wherever practicable. The sur- face is covered with forests and mountains. The principality possesses iron mines, and produces agates, chalcedony, &c., which are wrought for exportation. It has a market town of the same name, 23 m. E. S. E. of Treves ; pop. 2,249. The principality was from early times a separate state under the suzerainty of the palatines of Deux-Ponts. In 1802 it came into possession of France, and in 1815 of Prussia, which in 1817 ceded it to Oldenburg. BIRKENHEAD, a market town and port of Cheshire, England, on the estuary of the Mer- sey, opposite Liverpool, with which it has con- stant communication by several steam ferries ; pop. in 1871, 65,980. A railway 16 m. long connects it with Chester, whence other roads diverge to various parts of the kingdom. Al- though a place of considerable antiquity, hav- ing been founded at least as early as the 12th century, it dates its present prosperity from a
