Sub-fam. 4. Polioptilinae.–The Gnatcatchers, with the sole genus Polioptila, have very slender bills, moderate rictal bristles, metatarsi scutellated anteriorly, shortish wings, and graduated tails. They are blue-grey above, with black rectrices, externally marked with white; and are greyish or white below. White shews occasionally on the wing, and some males have black heads.
Sub-fam. 5. Miminae.–The American Mocking-birds have fairly long bills, which are little decurved except in Harporhynchus, but are frequently notched, and bristly at the gape. The metatarsi are usually strong and distinctly scutellated in front, though more slender in Oreoscoptes and Melanoptila, and sometimes quite smooth in the latter and Galeoscoptes; the wings are shortish and rounded, with well-developed outer primary; the tail is rather long and is generally broad and much graduated, but is narrower and squarer in Oreoscoptes. The usual coloration is dull brown, rufous, and grey, varied by white on the remiges and rectrices, and by an occasional black cap or chestnut vent; Melanoptila, however, is uniform purplish- or bluish-black, Rhodinocincla rosy or rufous below in the male and female respectively, with superciliary streak to match. Oreoscoptes, Mimus, Cichlherminia, and Harporhynchus often shew spots beneath and Donacobius dusky bars, Mimus trifasciatus has a dark chest-band.
The Turdidae occupy the whole globe, being characteristically, though not invariably, migratory.[[286]] Of the Turdinae, Thrushes abound in the Neotropical Region, and–if we include the Ground-Thrushes–are common in the Ethiopian, Indian, and Australian, but the Palaearctic and Nearctic are poorly supplied: Chats, Robins, Redstarts, Nightingales, Hedge-sparrows, and their nearest allies are mainly Palaearctic, Ethiopian, and Indian; though Sialia reaches America, Pratincola Celebes, and Petroeca Samoa. Nesocichla is restricted to Tristan da Cunha, Turnagra to New Zealand, Phaeornis to the Sandwich Islands; while Madagascar possesses peculiar forms both of this Sub-family and of the Sylviinae. The last-named, however, are chiefly Palaearctic, and visit the southern Old World in winter; yet two species of Acrocephalus breed in Australia, Miro and Myiomoira occupy New Zealand, Tatare and Psamathia are Polynesian, one species of Phylloscopus reaches Alaska, Regulus occurs thence to Panama, and so forth. The Polioptilinae and Miminae inhabit North and South America; the Myiodectinae range from the more western United States to Bolivia and Brazil. Of the last groups several forms are confined to the Antilles, and of the Miminae three to the Galápagos.
Thrushes inhabit wooded country, and reach an altitude of twenty thousand feet in some latitudes; they feed chiefly on the ground, where they hop about scratching or searching for worms, molluscs, and insects. Snails are habitually cracked on some favourite stone by the Song-Thrush, and fruit is also eaten. The strong rapid flight is undulating and frequently low, but flocks cover vast distances on migration; Ground-Thrushes are naturally more terrestrial and resident, while the solitary Rock-Thrushes haunt stony hills, rocks, and ruins. This Sub-family comprises some of our very finest songsters, the Song-Thrush or Mavis vying with the Nightingale, which gladdens both day and night, and the Blackbird uttering delightfully mellow notes; but chirping sounds and harsher screams are common. Phaeornis sings prettily. The typical Turdine nest is a massive cup of grass, cemented with mud and inlaid with finer herbage; but other materials are constantly added, while mud, dung, or rotten wood constitutes the lining in the case of the Song-Thrush, and occasionally elsewhere. It is usually placed in trees or bushes, but not infrequently in cavities in trunks, walls or rocks, and sometimes on the ground in heather, banks, and so forth. The eggs may be greenish or bluish with reddish-brown or purplish spots and streaks, or glossy blue with or without black or brown markings; Rock-Thrushes have them light blue with faint stains, or pinkish with rusty freckles, Turnagra whitish with black-brown spots.
As regards the Saxicoline and Ruticilline forms attention should be drawn to the jerky, flitting flight, the "chacking" alarm-note and the rarer song of our Wheatear, the similar habits of our Stonechat and Whinchat, not to mention other allied forms; as well as to the pleasant notes of Redstarts, Redbreasts, Blue-throats, and Hedge-sparrows, and the common habits of hopping, flirting the tail, and drooping the wings. The nests of Chats consist of grass and moss, often lined with hair, feathers, or fur, and are usually placed in holes of various descriptions, or in rough herbage; the four to seven blue, greenish, or even whitish eggs being spotted or zoned with rufous, except in a few instances, such as our Wheatear, where markings are rare. Deserts and stony or furzy flats are favourite haunts. Petroeca adds bark, fibres, cobwebs, or lichens, and chooses sites in forks, or holes in trees and walls; the greenish or buffish eggs being marked with purplish, brown and grey. Cyanecula and Nemura select hollows in marshy spots, building with moss, grass, and leaves, like Robins; but the former, instead of reddish-white eggs with rufous spots, has them olive-coloured or dull greenish with faint rusty markings, as have the Nightingales, which place their fabric of oak or beech leaves on the ground or in low shrubs. Copsychus, Cossypha, Catharus, and Thamnobia nest as Robins do, in holes in banks, trees, or walls, and have similar eggs; Redstarts deposit five or six, which are light blue or white and very rarely spotted, in a structure of grass, moss, roots, hair, and feathers, placed in cavities of trees or masonry; Tarsiger and Notodela prefer hollows in banks and rocks, and lay blue and salmon-pink eggs respectively. Hodgsonius and Larvivora also have them blue. Chimarrhornis and Rhyacornis nidificate like Redstarts, but their eggs are greenish-white with rufous or yellowish spots; the shy Cittocincla haunts thick woods, and deposits four oily-green eggs, with brown and purplish spots and dashes, on a bed of leaves and grass in holes in trees; the unsuspicious Sialia utilizes cavities in stumps or buildings, the nest and its contents resembling those of a Redstart. The breeding habits of the Hedge-Sparrow need no description, and those of the Alpine Accentor differ little, except that rocky sites are chosen.
In the above section the number of eggs varies from four to seven. The flight is feeble as compared with that of Thrushes, most species feeding chiefly upon the ground and being more insectivorous, though Redstarts and Chats will take insects on the wing.
The habits of the active Sylviinae are much more uniform; they seldom fly far, except on migration, and a few flit about like Wrens; while Amytis, Stipiturus, Sphenura, and some species of Aedon run, or hop among the herbage, with upturned tail. They frequent trees, bushes, long grass or reeds, seldom flocking as does Regulus, and live on insects and their larvae, small molluscs and fruit, the first-named being either caught in the air or sought upon the leaves and branches. The song is usually clear and sweet, though often plaintive, metallic, or whistling; the Willow- and Wood-Warblers (Phylloscopus) trill: the Black-cap and Garden-Warblers (Sylvia) have beautiful songs, as well as grating alarm notes; the Cataract-bird (Origma) runs along rocky water-courses emitting shrill cries; the Reed- and Sedge-Warblers (Acrocephalus), the skulking Cettia, and other marsh- and grass-frequenting forms, utter more or less jarring sounds, generally from some bush, whence they quickly drop to cover; while the Grasshopper-Warblers (Locustella) have a peculiar cricket-like note.
The nest may be a thin or fairly substantial cup of grasses, bed-straw (Galium) and the like, occasionally lined with hair, and placed in bushes or rank herbage, as in the Black-cap, Garden-Warbler and White-throats (Sylvia); or a firmer structure, including wool, moss, feathers, reed-flowers, or even lichens, built on the ground, in shrubs, in sedge, or between reed-stems, as is the case in Locustella, Acrocephalus, Aedon, and Hypolais. Phylloscopus, as well as some African and many Indian and Australian members of the Sub-family, fashion a round ball of grass and a little moss, lined with finer grasses, hair, down, or feathers, and generally place it close to the earth; Regulus hangs a cup of moss and spiders' webs, bedded with feathers, below the end of a conifer or other branch, or even builds it in creepers. Savi's Warbler (Locustella luscinioïdes) makes a Rail-like nest of broad grass-blades (Glyceria) in sedges, Myiomoira one of bark, grass, wool, moss, and fibres in holes in trees, Miro a similar fabric on their branches, Acanthiza a domed hanging structure of like materials, Origma a ragged pendent mass of moss and roots, lined with fur or feathers, under rocks. Orthotomus (Tailor-bird) and some species of Franklinia, Prinia, and Cisticola stitch together the edges of a leaf or leaves to sustain their nest of grass, cotton, wool, and hair.
The number of eggs is generally from three to six, but as many as twelve are found in Regulus. The colour is buffish-white with brownish and violet-grey spots in Savi's Warbler; pinker with delicate red-brown freckling in the Grasshopper-Warbler; rich red-brown in Cettia and Chthonicola; similar or varying to blue, green, white or pinkish, with or without red or brown spots, in Prinia–even in the same species; little different in Cisticola; bronzy-brown in Pyrrholaemus; white or purplish with dark markings in Sericornis; white in Origma and Cryptolopha. In Sylvia the eggs are greenish- or yellowish-white with olive, brown, green, or reddish spots; in Acrocephalus they are decidedly greener; in Aedon greyer with brown and dull violet markings; in Phylloscopus and Acanthiza white, usually with dark red or purplish spotting; in Hypolais lilac-pink with blackish or brown blotches or streaks; in Regulus white, freckled or entirely suffused with yellowish or ruddy dots.
Myiodectes frequents woods and thickets, and has somewhat Thrush-like habits; the voice is powerful, clear and metallic; while the food consists chiefly of berries, though insects are hawked for in the air. The nest, placed on bushes, stumps, banks or rocks, is made of sticks lined with soft materials, or of twigs, roots, and moss, and contains from three to six eggs, not unlike those of the Redbreast.