All birds

Raptors are defined by equipment rather than ancestry: a hooked bill for tearing, strong feet with sharp talons for gripping, and eyes set forward on a broad head. The word is a description, not a family — hawks, eagles and falcons are not one another's closest relatives, and falcons sit nearer to parrots and songbirds than to hawks. Most species show reversed size dimorphism, the female larger than the male, which is unusual among birds. In the air, note whether the bird soars on broad, still wings or drives forward in quick, stiff beats.

Songbirds are the passerines: small perching birds with three toes forward and one back, an arrangement whose tendons lock the foot shut on a branch and let the bird sleep without falling. The order's real distinction is the syrinx, the vocal organ at the base of the windpipe, which here carries several pairs of muscles and can produce two independent notes at once. The name misleads, though: crows, jays and ravens are passerines and hardly sing. This is by far the largest division in the guide, so narrow it by size, bill shape and habit before you look at colour.

Waterfowl — ducks, geese and swans — share a flat bill edged with lamellae that strain food from water and mud, webbed feet set well back, and dense down kept waterproof by oil from a gland at the tail base. The young leave the nest within a day and feed themselves. One seasonal trap: males of many ducks moult into a dull eclipse plumage in late summer and look confusingly like females, so check bare-part colour and the wing patch. Watch too how a bird feeds — upending with its tail in the air, or diving and staying under.

Seabirds are a working category, not a single family: albatrosses, gulls, gannets, auks and their relatives reach the sea from quite different branches of the bird tree. What they share is a way of life. Most have a salt gland above the eye that concentrates the salt swallowed with seawater and sheds it, often as a visible drip at the bill tip. They tend to be long-lived, slow to mature and to lay few eggs, and they nest in dense colonies on cliffs and islands. Note that gulls are not reliably coastal — several species forage inland, following the plough.

Waders — plovers, sandpipers, curlews, godwits and their allies — are built along one plan: long legs for walking on soft ground, a long bill for probing, and dense plumage that keeps out cold water. Most breed in the far north and migrate extraordinary distances, so they moult twice a year and an autumn bird can look nothing like the spring illustration. Identification therefore leans on structure and sound: relative leg length, where the bill curves and how heavy it is, and the flight call, which at the range you actually get is often more diagnostic than colour.

Woodpeckers are built for vertical work. The bill is a chisel, the feet are zygodactyl — two toes forward and two back — and the tail feathers have stiffened shafts that press against the bark as a third point of support. The skull is reinforced against the shock of repeated strikes, and the tongue is anchored by a hyoid apparatus looping over the back of the head, which lets it shoot forward into a hole. Drumming is a territorial signal, not feeding, and its rhythm and length often identify a species better than a glimpse does.

Owls share adaptations for hunting in low light. The eyes face forward and are fixed in their sockets, so the bird turns its whole head, and the neck can rotate roughly three-quarters of a turn. Feathers around the face form a disc that funnels sound towards ears set asymmetrically on the skull, letting the bird judge a sound's height as well as its direction. The leading edge of the flight feathers is combed and the surface velvety, so flight is nearly silent. By day, finding an owl usually means reading a shape in a tree rather than a colour.

Hummingbirds are a New World family, and the species in this guide come from the Americas. They hover by sweeping the wings through a figure of eight, so the upstroke generates lift as well as the downstroke, and many beat forty to eighty times a second — the hum that gives them their name. At night, or in cold weather, a bird may enter torpor and let its body temperature and heart rate fall sharply to save energy. Bill length and curvature usually match the flowers a species feeds at, and are often the quickest clue after overall size.

Pigeons and doves are one family, Columbidae; the two words carry no taxonomic difference, though the larger species tend to be called pigeons and the smaller ones doves. All are plump-bodied with a small head, a short neck and short legs set well back, and all fly fast and straight with a whistling or clattering note from the wings. One trait is nearly unique among birds: they drink by suction, dipping the bill and pumping water without lifting the head. Identification rests on tail pattern, wing bars and the shape of the bowing display flight.