The great black-backed gull is the largest gull on Earth. A big one can catch an adult puffin then swallow it whole. Learn your UK birds free at learn-birds.com #birds #UKbirds #greatblackbackedgull

A swift can't perch. All four toes point forward and its feet are the shortest of any bird, good only for clinging to a wall. Its name Apus even means 'without feet'. Learn your UK birds free at learn-birds.com #birds #UKbirds #swift

Dunnocks look shy and monogamous but their love lives are chaotic. A female often mates with two or three males in quick succession. All of them then help feed her chicks, thinking they might be the father. Learn your UK birds free at learn-birds.com #BirdOfTheDay #ABCD #birds #dunnock

Researchers coloured male swallows' breasts a deeper red with a marker and within a week the birds' own testosterone had climbed by over a third. Looking the part seems to change the bird itself. Learn your UK birds free at learn-birds.com #birds #UKbirds #swallow

A turtle dove has nothing to do with the reptile. The name copies its song. Latin turtur mimics that soft rolling turr turr purr you hear on a warm June morning. Learn your UK birds free at learn-birds.com #birds #UKbirds #turtledove

For an owl the little owl eats oddly small prey. Beetles, earwigs, worms make up much of its diet, gathered on foot in the half light. Learn your UK birds free at learn-birds.com #birds #UKbirds #littleowl

Where trees are scarce the stock dove goes underground. It will lay its eggs down a rabbit burrow. A pigeon nesting in a hole in the ground is a genuinely odd sight. Learn your UK birds free at learn-birds.com #birds #UKbirds #stockdove

Count the Pochard on a British lake in winter and you will see far more drakes than ducks. Dominant males hold the grounds nearest the breeding range, pushing the females much further south. Learn your UK birds free at learn-birds.com #birds #UKbirds #pochard

Not every 'seagull' stays by the sea. Some lesser black-backed gulls migrate all the way down Africa's Great Rift Valley to spend winter on lakes in Ethiopia and Kenya. Learn your UK birds free at learn-birds.com #birds #UKbirds #lesserblackbackedgull

House sparrows aren't native to most of the world. Every one you see in the USA, Australia or New Zealand descends from birds deliberately released there in the 1800s. Britain's own population has dropped by 70% since the 1970s. Learn your UK birds free at learn-birds.com #BirdOfTheDay #BirdNaps

The dumpy corn bunting has a wild love life. One male can hold a territory with many mates at once. Records run to eighteen females for a single hard-working male in one season. Learn your UK birds free at learn-birds.com #birds #UKbirds #cornbunting

A house martin's nest is roughly a thousand beakfuls of mud, each pellet gathered from a puddle and stuck on one at a time. No wonder they'd rather repair last year's than build from scratch. Learn your UK birds free at learn-birds.com #birds #UKbirds #housemartin

Fulmar chicks have a nasty defence trick. If threatened they can projectile vomit a foul-smelling oily substance at attackers from some distance. It mats a predator's feathers and can even prove fatal to other seabirds. Learn your UK birds free at learn-birds.com #BirdOfTheDay #ItsAllWhite #fulmar

Crossbill chicks hatch with perfectly straight bills. The famous cross grows in over the first few weeks as the tips lengthen. Only then can a young bird prise its own seeds from a cone. Learn your UK birds free at learn-birds.com #birds #UKbirds #commoncrossbill

The common gull is not our commonest gull. The name likely means common as in ordinary, or comes from the rough common grazing land where it nests. It never meant numerous. Learn your UK birds free at learn-birds.com #birds #UKbirds #commongull

The tiny redpoll has a stretchy pouch in its throat. It stuffs seeds in fast then slips off somewhere sheltered to digest them slowly. A neat trick for feeding without freezing in the open. Learn your UK birds free at learn-birds.com #birds #UKbirds #lesserredpoll

Female mallards can lay eggs fertilised by more than one drake in a single clutch. Each duckling in the nest might have a different father. Ducklings from the same egg batch are sometimes only half siblings. Learn your UK birds free at learn-birds.com #BirdOfTheDay #BirdsUpClose #birds #mallard

A redwing rarely spends two winters in the same place. One ringed in a British garden has turned up in Italy or Greece the following year. They wander wherever the weather and berries take them. Learn your UK birds free at learn-birds.com #birds #UKbirds #redwing

After a chick hatches the parent gull carries the broken shell far from the nest. Tinbergen showed why. The white lining inside is a beacon that tells crows exactly where dinner is. Learn your UK birds free at learn-birds.com #birds #UKbirds #blackheadedgull

Mute swan cygnets sometimes ride on a parent's back while it swims. This keeps them warm and safe from pike lurking below. They can hitch a lift this way for the first few weeks of life. Learn your UK birds free at learn-birds.com #BirdOfTheDay #Parenting #birds #muteswan

The male Whitethroat builds several rough cock nests around his patch. The female inspects them like show homes then lines the one she likes best to finish it. The others go to waste. Learn your UK birds free at learn-birds.com #birds #UKbirds #whitethroat

In winter a pied wagtail guarding a riverbank feeding patch will sometimes let a second bird share it. When there's plenty to go round, an extra pair of eyes on defence earns its keep. Learn your UK birds free at learn-birds.com #birds #UKbirds #piedwagtail

Long-tailed tits huddle in a row on a branch to share body heat on cold nights. The oldest bird usually takes the middle spot, the warmest place in the line. Youngsters often get pushed to the chilly ends. #BirdOfTheDay #BestOfTheMonth #longtailedtit

The dipper carries an oversized secret. Its preen gland is about ten times larger than any other songbird's, packing enough oil to waterproof a bird that walks the riverbed underwater. Learn your UK birds free at learn-birds.com #birds #UKbirds #dipper

Great crested grebes eat their own feathers. They even feed feathers to their chicks. Nobody's fully sure why, but it may help protect their stomachs from sharp fish bones. Learn your UK birds free at learn-birds.com #greatcrestedgrebe #birds #BirdOfTheDay #Coastal&River

A female sparrowhawk can weigh twice as much as her mate. It's one of the biggest size gaps between the sexes in any bird of prey, so the two hunt different prey and never squabble over dinner. Learn your UK birds free at learn-birds.com #birds #UKbirds #sparrowhawk

The Fieldfare is a flock bird until food gets scarce. Then one may claim a single berry bush or windfall apples and guard it fiercely, chasing every rival off its private winter larder. Learn your UK birds free at learn-birds.com #birds #UKbirds #fieldfare

Goldfinches can hang upside down on teasel heads to winkle out seeds that other finches simply cannot reach. Their Latin name Carduelis literally means thistle finch. A flock feeding together is called a charm. Learn your UK birds free at learn-birds.com #BirdOfTheDay #NaturalSeeds #Goldfinch

The redshank is the marsh's burglar alarm. Nervy and loud it is nearly always first to spot you then its ringing yelp puts every other wader on the mud to flight. Learn your UK birds free at learn-birds.com #birds #UKbirds #redshank

Great spotted woodpeckers hammer their heads into wood up to twenty times a second. Their skull has spongy bone and barely any cerebrospinal fluid to cushion the brain. That built-in shock absorption stops the bird from getting a concussion. #BirdOfTheDay #Woodland