The tyrant flycatchers (Tyrannidae) are a clade of passerine birds which occur throughout North and South America. They are considered the largest family of birds on Earth, with more than 400 species. They are the most diverse avian family in every country in the Americas, except for the United States and Canada. As could be expected from a family this large, the members vary greatly in shape, patterns, size and colours. Some Tyrant flycatchers superficially resemble the Old World flycatchers which they are named after but are not related to. They are members of suborder Tyranni (suboscines), which do not have the sophisticated vocal capabilities of most other songbirds.Most, but not all, species are rather plain, with various hues of brown, gray and white commonplace. Obvious exceptions include the bright red Vermilion Flycatcher, blue, black, white and yellow Many-colored Rush-tyrant and some species of tody flycathers or tyrants, which are often yellow, black, white and/or rufous, from the Todirostrum, Hemitriccus and Poecilotriccus genera. Several species have bright yellow underparts, from the Ornate Flycatcher to the Great Kiskadee. Some species have erectile crests. The crest is taken to the extreme in the Royal Flycatcher, which is plain but for a large black-spotted, red-and-blue crest which it fans out like a peafowl tail when excited. Several of the large genera (i.e. Elaenia, Myiarchus or Empidonax) are quite difficult to tell apart in the field due to similar plumage and some are best distinguished by their voices. Behaviorally they can vary from species such as spadebills which are tiny, shy and live in dense forest interiors to kingbirds, which are relatively large, bold, inquisitive and often inhabit open areas near human habitations. As the name implies, a great majority of tyrant-flycatchers are entirely insectivorous (though do not necessarily specialized in flies). Tyrant flycatchers are largely opportunistic feeders and often catch any flying or arboreal insect they encounter. However, food can vary greatly and some (like the large Great Kiskadee) will eat fruit or small vertebrates (e.g. small frogs). In North America, most species are associated with a "sallying" feeding style, where they fly up to catch an insect directly from their perch and then immediately return to the same perch. Most tropical species however do not feed in this fashion and several types prefer to glean insects from leaves and barks. Tropical species are sometimes found in mixed-species foraging flocks, where various types of passerines and other smallish birds are found feeding in proximity.The smallest family members are the closely related Short-tailed Pygmy Tyrant and Black-capped Pygmy Tyrant (the first species usually being considered marginally smaller). With a total length of a mere 6.5-6.8 cm (2.5-2.7 in) and a weight of 4-5 grams, they are the smallest passerines on earth. The minuscule size and very short tail of these flycatchers often makes them lends them a resemblance to a tiny ball or insect. The largest tyrant flycatcher is the Great Shrike-Tyrant at 29 cm (11.5 in) and 99.2 grams (3.5 oz). A few species such as the Streamer-tailed Tyrant, Scissor-tailed Flycatcher and Fork-tailed Flycatcher have a larger total length (up to 41 cm/16 in), but this is mainly due to their extremely long tails. In fact, the Fork-tailed Flycatcher has relatively the longest tail feathers of any known bird.A number of species previously included in this family are now placed in the family Tityridae (see Systematics). Sibley and Alquist in their 1990 bird taxonomy had the genera Mionectes, Leptopogon, Pseudotriccus, Poecilotriccus, Taenotriccus, Hemitriccus, Todirostrum and Corythopsis as a separate family Pipromorphidae, but although it is still thought that these genera are basal to most of the family, they are not each other’s closest relatives.
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