Bird migration

Cemlyn - During the summer, Cemlyn is home to one of Wales' most important tern colonies, with hundreds of pairs of Sandwich tern joined by smaller numbers of Arctic and common tern. Spring and autumn can produce passage waders and other migrant birds, such as whinchat and wheater - rarer visitors to the area have included woodchat shrike and black-headed bunting. Between July and October a westerly or north-westerly wind can lead to excellent seawatching, with storm petrels, skuas and shearwaters often recorded.

Llanbwchllyn - From the thatched roof of the bird hide, large flocks of coot can be viewed in winter. There have been occasional sightings of great northern diver and bittern, but more likely sightings are large numbers of tufted duck and goosander as well as rarer birds like gadwall and goldeneye.

Pwllpatti - A bird hide overlooking an old ox-bow of the River Wye which floods in winter. It is home to the largest wigeon roost in Powys and also a good place for teal. Species also likely to be seen are common sandpiper, redshank, oystercatcher, little egret, tufted duck and mallard.

Skomer Island - a spectacular summer seabird colony, Skomer is also a great place to see migrant birds passing through in spring and autumn. Regulars such as spotted flycatcher and redstart are often joined by more unusual visitors. Recent highlights have included woodchat shrike, eastern subalpine warbler and dark-eyed junco - a real rarity from North America.

Teifi Marshes - One of the best wetland sites in Wales, attracting large numbers of wintering wildfowl like teal and wigeon. Water rail, snipe, curlew and lapwing are all regular winter visitors, and passage can bring other waders such as ruff and green sandpiper, as well as songbirds stopping off to feed before completing their migration - a white wagtail ringed on the reserve was found in Vidvikursveit, Iceland, 1730km away, 76 days later.

Spring migration is known as the great rush north, as birds race back to their more northerly breeding grounds having spent the winter in milder regions further south. There's an air of urgency, each bird eager to claim the best territory or find the best mate, so most spring migrants rarely pause in one place for long until they've reached their final destination.

Spring sees the return of many of our summer visitors, birds that breed in the UK but winter in southern Europe, Africa or even further afield. Many of these are insect-eaters that can't find enough food here in winter. They can appear as early as March, with wheatears, chiffchaffs, sand martins and ring ouzels often the first to arrive.

Things heat up in April, with more birds arriving all the time. Swallows, willow warblers, blackcaps, redstarts, tree pipits, yellow wagtails and house martins are often spotted early in the month, with later arrivals including garden warblers, whinchats, turtle doves, swifts and pied and spotted flycatchers. April also sees the return of the cuckoo, whose call is widely regarded as the classic sign of spring.

Breeding seabirds also arrive on our shores in spring. Arctic, Sandwich and little terns can sometimes be seen flying over inland lakes as they head for their coastal nesting areas, whilst common terns will return to these freshwater sites for the summer. Puffins, guillemots, razorbills and gannets all reappear at their breeding grounds on rocky cliffs or islands after spending the winter out at sea. Birds of prey are another feature of spring migration, with summer visitors including ospreys, hobbies and the rarely seen honey buzzard.

Spring is also a good time to find rarer migrants that don't typically breed in the UK. Easterly winds can push migrating birds off-course, resulting in scarcely-seen species like wrynecks and bluethroats being found on our shores. Southerly winds and favourable conditions can cause birds that usually breed further south to fly too far, hitting the UK instead. Hoopoes, bee-eaters and black-winged stilts are some of the most commonly encountered, with pairs occasionally remaining here over summer and nesting!

In early summer most birds are busily raising chicks, but with no parental duties to worry about adult cuckoos are already heading south in June. By July they can be back in the Sahel, feasting on the caterpillars of African moths and planning the next leg of their journey to the rainforests of central Africa.

July sees the first migratory wading birds returning to our coasts and wetlands, busily feeding and re-stocking their fat reserves for the last push of their journey down to Africa or beyond. Wader migration steps up a gear in August, and with luck scarcer species like little stint and curlew sandpiper can be spotted.

July is also when terns start to spread out from their breeding colonies and can be found scattered around our coasts, preparing for their own journey south. For Arctic terns, this journey could take them as far as Antarctica. They make the longest migration ever recorded, clocking up over 59,000 miles; an incredible distance equivalent to flying twice around the planet!

During August, swifts start out on their non-stop flight down to South Africa. Swallows and house martins start gathering in August and September, forming large flocks at reedbeds and famously lining up along telegraph wires before they too decide it’s time to leave, flying their way back down across Europe and the Mediterranean, heading for Africa.

Autumn migration has a very different feel to the great northerly rush of spring. The urgency is gone, birds slowly working their way south towards their wintering grounds, often stopping off for days or even weeks to refuel for the rest of their journey. 

As our own summer visitors gradually disappear, birds that spent the summer in more northerly countries start to pass through on their way south. Huge numbers of flycatchers, chats and warblers arrive on our coasts from Scandinavia, all with one thing on their mind: the journey to Africa.

This is often the best time to find rare birds amongst the more common migrants. Inexperienced young birds making their first journey south are more likely to stray off-course, so species that would normally not be seen in the UK sometimes turn up. Weather is the key: westerly fronts moving across the Atlantic can bring American waders and songbirds, whilst easterly winds could carry Siberian gems like the beautiful red-flanked bluetail.

Late summer into autumn is also a great time for seawatching - wrap up warm, find a comfortable spot on a headland and scan for migrating seabirds. Thousands of auks, kittiwakes and gannets leave their colonies and head out into the Bay of Biscay and the North Atlantic for the winter. Search through flocks of Manx shearwater for their rarer cousins, including Balearic, great and Cory's shearwaters, and look for marauding skuas  - Arctic and great skuas are the most common, but with luck you can spot pomarine and sometimes long-tailed skuas, too.

The tiny red-necked phalarope, a sparrow-sized wader that breeds on pools in Shetland, has the Herculean task ahead of not only flying right across the Atlantic but then crossing the Americas to spend the winter months in the equatorial Pacific, bobbing around on the sea between Ecuador and the Galapagos islands.

In October, it’s the turn of thrushes, finches and buntings to make the journey across the North Sea to the UK. If the conditions are right, spectacular movements can occur involving thousands of birds. It's a delight for the senses, vast clouds of finches and thrushes passing overhead in endless flocks, accompanied by the nasal croak of bramblings, the laughing rattle of fieldfares and the piercing call of redwings. In foggy or rainy conditions, these birds can be grounded in an event known as a 'fall', where birds seem to cover the ground and any vegetation. On one such October day in 2012, observers at Yorkshire's Spurn Point recorded over 38,000 birds!

October also sees the return of thousands of swans and geese, flying in their famous V-formations. Pink-footed geese pour in from Greenland and Iceland, stopping off at favoured sites in Scotland, such as the Montrose Basin where over 90,000 have been recorded on a single day. As autumn progresses, the geese filter south into England. 

Waxwings arrive for the winter from Scandinavia, and you might also see large numbers of the delicate goldcrest, Europe’s smallest bird weighing the same as a ten pence piece and yet able to make its way across the North Sea to spend its winter here with us.

Many of the birds that winter in the UK arrive in autumn, but cold weather or a lack of food in northern Europe can drive large numbers of birds to cross the North Sea during winter itself. 

Waxwings are the most eagerly anticipated winter arrivals, their colourful plumage making them a favourite of many UK birdwatchers. Some winters only see a handful of these beautiful birds making the journey to our shores, but in other years they appear in huge numbers. These mass influxes are known as irruptions, and occur when the weather in Scandinavia and northern Russia is particularly harsh, or if there has been a poor crop of their favourite food, berries. Waxwings are often found in supermarket carparks, feasting on berry-laden trees.

Late December into January also tends to be when the highest number of smews can be seen in the UK. The striking black and white males don't stray far from their continental breeding grounds, so most individuals seen here are either females or young birds, known as red-heads thanks to the auburn feathers on their crown and nape. Smew favour gravel pits, but can be found on almost any large body of freshwater.