Bird Migration Map

It shows where 33 of the world's great migratory birds are through the year, animated on a world map. Each species has its real route, from the breeding grounds to the wintering grounds and back, with the stopovers the birds use, and a calendar of when they travel. The flocks on the map leave, fly and arrive on those dates, so on any day you can see which birds are on the move, which way they are heading and roughly where they are. Open a species for its photo, its journey in numbers, the story of the route and the live webcams along it.

The clock is live: the map opens on today's date, with the day and night line where it really is, and the flocks are where that species typically is at this point in the year. The birds themselves are not GPS-tracked in real time; no map of a whole species could be, because a species is millions of individuals. What you see is the well-documented pattern, from tracking studies and decades of ringing and counting, applied to today. The "Today" button always brings you back to now.

In North America and Britain there are two seasons. Spring migration runs from late February to early June and peaks in late April and May, when the songbirds pour north. Autumn migration is longer and more spread out: shorebirds start south in July, hawks and swallows go in September, and geese, swans and cranes are still arriving in November. The southern hemisphere is the mirror image: New Zealand's shearwaters and godwits head north in March and April and come home in September and October. Press play on the timeline to watch the whole year in a minute.

The Arctic tern. It breeds in the Arctic and spends the other half of the year on the edge of Antarctica, a round trip of about 70,000 km (43,500 mi), and over a 30-year life it flies the equivalent of three return trips to the Moon. For a single nonstop flight the record belongs to the bar-tailed godwit, which flies from Alaska to New Zealand, 11,000 to 13,000 km (6,800 to 8,100 mi), in eight to eleven days without landing. The sooty shearwater's 64,000 km (39,800 mi) figure-of-eight around the Pacific is the longest migration ever recorded with an electronic tag.

Food. The far north has an enormous flush of insects, plants and daylight in summer, enough to raise a brood quickly and with few predators, but nothing to eat in winter. So birds commute: north to breed where the summer food is, south to where it is warm enough to survive the winter. Each species' route and timing is tuned to that: hummingbirds follow the flowers, geese follow the thaw, hawks wait for the thermals and shorebirds time their stops to the hatching of horseshoe crabs and mud shrimp.

Several compasses at once. Birds read the sun by day and the stars by night, they sense the Earth's magnetic field, and they remember landmarks, coastlines and even smells. Some learn the route from their parents: geese, swans and cranes travel as families. Others are born knowing it: a young cuckoo has never met its parents and still finds the Congo rainforest on its first try, and Manx shearwater chicks leave Wales alone for South America. Birds that have flown a route once will return to the same tree, the same lawn or the same stretch of beach year after year.

Most small birds do: warblers, thrushes, sparrows and shorebirds take off an hour after dusk and fly through the night, when the air is calmer and cooler and there are fewer hawks about. On a good night in spring or autumn hundreds of millions of birds are aloft over North America, which is why so many are heard calling overhead in the dark. Soaring birds such as hawks, storks and cranes do the opposite: they need the thermals that only rise in daytime, so they travel by day and stop at dusk. The night layer on the map shows where it is dark right now.

Most migration happens between a few hundred and 2,000 metres (6,600 ft) up, where the winds help, but the records are remarkable. Bar-headed geese have been tracked above 7,000 metres (23,000 ft) crossing the Himalaya, and a flock of whooper swans was reported by a pilot at 8,000 metres (26,200 ft). Cruising speeds are typically 40 to 70 km/h (25 to 43 mph); the great snipe averaged 97 km/h (60 mph) over 6,800 km (4,200 mi) nonstop, with no help from the wind. With a tailwind, geese cover more than 1,000 km (620 mi) in a day and a night.

Each species has a departure window and a flying time for both legs of its journey, plus the stopovers where it rests. The map gives each bird in a flock its own departure date and pace within those windows, so the flock strings out along the route just as a real population does. A species counts as on the move when a typical bird, one leaving in the middle of the window, is between its two grounds today. "About to leave" means that bird departs within three weeks. The windows are typical for the population described; an early spring or a late cold snap can shift a real migration by a week or two.

Yes. Open any species on the map and the panel lists the live webcams on its route and at its breeding and wintering grounds, bird cams first. The osprey nests in Scotland, Oregon and New Jersey fill in late March and April and empty again in August; the stork nests of Germany and Latvia follow the same rhythm; the eagle and falcon cams are busy from February; and the feeder cams in Alberta and the Andes show whatever is passing through. The pins on the map are the same cameras: click one for a preview and a link to watch it live.

A flyway is one of the broad corridors that migrating birds funnel through, shaped by coastlines, mountain ranges and the places birds can rest and feed. Conservationists recognise eight or nine major ones: four down the Americas, three between Europe or western Asia and Africa, one through central Asia to India and one from Siberia through East Asia to Australia and New Zealand. Switch the Flyways layer on to see them as ribbons under the routes; most of the species on this map follow one of them.