London
WWT London Wetland Centre is a haven for hundreds of species of water birds, mammals and insects, but there are a handful of ‘stars’ that visitors are always particularly excited to spot.
In the summer months those include the gregarious lapwing and the undeniably cute water vole, while the winter months bring significant numbers of snipe, bittern and other migrating birds to our reserve.
Whether you’re visiting us in rain or shine, these species are the ones you simply shouldn’t miss...
Summer
Sand martins
In the spring these amazing little wetland birds fly all the way from the UK from sub-Saharan Africa. And when they arrive they still have enough energy to dig a tunnel up to 90cm long in a vertical sand bank and construct a nest chamber of feathers, leaves and grass at the end of it.
Sand martins lay up to five pure white eggs in late May after which both parents share the job of sitting on the eggs until they hatch, about two weeks later. Then more work is required, as they have to collect enough insects to keep their demanding chicks happy for the next three weeks until they are ready to fly.
Rather than take a well-earned breather, the birds then generally go on to raise a second brood, just in time for the return journey to Africa – a staggering 5000 mile round trip.
Sand martins depend on the sand banks and sand pits in which they make their nests and are threatened by drought conditions in Africa during the winter months, which have caused several crashes in their numbers.
Lapwing
The lapwing is a gregarious species that forms large flocks after breeding. They feed on worms and a variety of invertebrates on or close to the surface of the soil, by using the stand, run-a few-steps, pause, bob and peck technique.
They are subject to food stealing (kleptoparasitism) by black headed gulls, but try to avoid this by feeding at night. Nocturnal feeding increases around the time of the full moon when these birds tend to roost during the day.
Lapwings tend to choose nesting sites away from hedges, walls or trees where watchful crows may perch, and nest on bare ground or where vegetation is cropped short. Wherever the nests are situated, it is imperative that there is a rich supply of invertebrate food for the chicks nearby.
During February, males begin to perform display flights over breeding grounds in which they climb steeply upwards before tumbling down and appearing out of control close to the ground. Between March and early July, three or four well-camouflaged eggs are laid in a scrape on the ground. This is often on a slight mound. The chicks are able to run shortly after hatching.
If the nest is threatened, lapwings will mob predators and try to distract them away from the young, which lie flat against the ground. Unfortunately, lapwings will not start to defend their eggs until the clutch is complete. Because one egg is laid per day, if predation starts when the first or second eggs are laid, they may never get going. Successful pairs may return to the same spot the following year.
Common tern
The black-capped, white-bodied common tern is well named since it is widespread on European coasts from spring until late autumn.
It closely resembles the arctic tern and often mixes with it, but it is stouter, with a shorter tail and a longer red bill with a black tip.
Nicknamed the ‘sea swallow’, the common tern flies buoyantly and gracefully and typically hovers over the water before plunge-diving for prey with little hesitation, before swallowing it down or carrying it to the nest in its bill.
Common terns breed along coasts with shingle beaches and rocky islands, on rivers with shingle bars and at inland gravel pits and reservoirs. They also feed along rivers and over freshwater.
Migrating birds can be seen offshore in autumn. While they spend their summers in the temperate regions of Europe, Asia and east and central North America, they are strongly migratory and winter in coastal tropical and subtropical regions.
Water vole
Water voles lack visible ears and have a rather blunt (cute) face, with a furry tail. They are only aquatic in Britain. European water voles are genetically different, live in fields and can be agricultural pests.
Water voles in Britain may have developed an aquatic escape mechanism in the absence of a native species of mink. Water voles are not well adapted to water, as they do not have webbed feet and can sink after 30 minutes. They only use water to travel and to escape predation. The "plop" also warns other animals of danger.
Water voles need steep and very grassy banks with good cover, as in slow, lowland rivers. Not good for water voles are spate rivers, rocky and tree lined rivers. Reedbeds also form good habitats with plenty of shelter and food, and the voles nest in tussocks. Nests are made of fine grassy material in the centre of these tussocks.
Females will eat snails, crayfish and caddis flies to gain extra nutrients while pregnant. In winter, water voles feed on rhizomes, bulbs and bark, stripping waterside trees. They will coppice small saplings. Food is stored in the burrows.
Winter is a critical period due to the shortage of food and increased predation is a problem as there is less cover. Water voles are very territorial and aggressive to their neighbours, and females will disperse up to 4km under cover if conditions are suitable.
Tunnels are dug with the teeth, and the burrow system is extensive with chambers for the nest and food storage. The burrows do not have spoil outside the holes (rat burrows do). There are also feeding lawns outside burrows, which are flat, short cropped platforms where the voles eat.
Young voles have high mortality rates of up to 70%, due to predation from mink, stoats, weasels, foxes, kestrels and herons. Rats predate both young and adult voles.
Bats
Bats are usually described as blind, but can fly by sight during daylight, and at night they can see far better than we can.
British bats feed on flying insects during the hours of darkness and, since catching small, fast moving insects is difficult enough in the daytime, bats have evolved a sense unique amongst terrestrial mammals to help them fly and catch their prey at night - echo-location.
The fact that bats use echo-location was only discovered in the 1940s and it took even longer for the idea to be accepted, largely because radar and sonar were new inventions and people couldn’t believe that bats were way ahead of human technology. But they were - by about 60 million years.
Fast, agile and equipped with a sensitive ‘radar’, bats are the masters of the night sky, but like a modern aircraft, they require large quantities of ‘fuel’ to stay airborne, and a single pipistrelle bat can eat up to 3000 small insects a night.
To further cope with the high levels of energy required for flight, bats have developed several energy saving tactics. They hibernate over winter when food is scarce, they go into ‘torpor’ (their body temperature drops to that of their surroundings) during the day and have a very low birth rate.
Although they occasionally have twins, most bats only have one baby a year. However, because of this low birth rate they live much longer than most mammals, up to ten or twenty times longer than ground dwelling mammals of a similar size such as shrews or mice. A Daubenton’s bat may live to be 40 years old.
Wetlands are good places to find bats, as they hunt over the water feeding on the hordes of insects with aquatic larval stages such as midges, caddis flies and mayflies.
In addition to the common pipistrelle, there are now known to be at least two other species of pipistrelle in Britain, Nathusius’ and the soprano - a new species only discovered ten years ago. We know we have all three species feeding over the London Wetland Centre.
Winter
Bittern
The bittern is a bird of large and shallow wet reedbeds. It is an extremely secretive bird for its size and, in spring, much more likely to be heard than seen.
The loud booming call of the territorial male has to be heard to be believed and can travel up to two kilometres if the wind is right. It is now known that each bird has its own distinctive voice.
Bitterns need large, extensive areas of reedbed with shallow pools or dyke edges in which to hunt fish, especially eels, and amphibians and invertebrates.
Because of the decline in the UK population, there has been something of a mania for creating large and wet reedbeds particularly for bitterns, over the last 10 years. This has been very successful. In 2004, there were at least 55 bitterns at 30 sites, including East Anglia, the Humber, Lancashire, Wales, Kent and Somerset. The UK BAP for bittern set a target for 50 booming bitterns by 2010, which has been exceeded six years early.
Bitterns make their way through reedbeds by grasping reeds, several at a time, with their huge toes. This movement is remarkably effortless for such a large bird. Males are polygamous with up to five females.
The nest is built in the previous year's dead reed stems and consists of a small platform. In lean times, chicks may turn to their smaller siblings and eat them.
The UK population is joined in winter by birds from the continent, and up to 3 of these birds may be present in the Main Reedbed at the London Wetland Centre. This reedbed is managed in 3 distinct beds of varying wetness, with pools dug to attract bitterns to feed. They are best seen from the Wildside Hide.
When startled, bitterns adopt a camouflage posture, with the neck stretched vertically and bill pointing straight up, making them blend in with the reeds.
Shoveler
The shoveler has a wide distribution, from America through to Europe, with a population estimated at 6 million birds.
The British population is insignificant in global terms with 1000-1500 breeding pairs, but it is in decline as a breeding species. However, it has increased as a wintering species since the 1960s.
Numbers reach a peak in Britain in the autumn, as birds move through from Scandinavia and Eastern Europe towards south west Europe and beyond. The peak count is often 10,000 birds.
Their specialised feeding method requires extensive shallow freshwater. They prefer well vegetated lakes and marshes with muddy shores, surrounded by grassland.
The specialised bill is used to filter food from water while dabbling, head dipping or up-ending. The sides of the bill have comb like projections, and water is drawn into the bill and pumped out through the sides by the tongue.
Aquatic insects, crustaceans, small molluscs, seeds etc are all trapped in the bill and swallowed. Larger food such as water beetles, snails and small fish may also be consumed. Small groups of shoveler may swirl in tight circles to create a whirlpool which brings food to the surface.
Wintering shoveler are one of the qualifying features for the SSSI designation of the London Wetland Centre.
Gadwall
The Gadwall is slightly smaller than the mallard with a smaller, squarer head. It can appear quite drab looking from a distance but, up close, its grey colouring is actually made up of fine speckling.
Gadwalls feed at the surface in shallow water then, in autumn and winter often flock on reservoirs and flooded pits. They often associate with coots in order to benefit from the food the coots from up from the bottom when they dive. They are renowned thieves, often snatching food from other ducks and coots.
They nest in nettle clumps and, during courtship, indulge in spectacular aerial displays in which pairs can sometimes collide.
The Gadwall is distributed widely across the globe, choosing to spend summers in the prairies of North America, British Columbia, Alaska, Europe, eastern Russia, Japan and China and winters in the southern USA, Mexico, Cuba, northern Africa, northern India and the Middle East.
Populations of the duck in Britain and Europe have been boosted in recent years by deliberate introductions.
Water rail
Water rails live a rather secret world - it seems like the last thing they want to do is to break cover and let anyone or anything see them.
Because they are seen so rarely most people are of the opinion that they are a scarce bird but, in fact, just about every bit of reedbed has its resident water rails.
Hidden in dense vegetation, they are more easily located by their sounds, which are not pleasant. They have been described as sounding like a pig being seized, beaten and strangled.
Water rails are compressed laterally, making them very thin and able to slip through reeds easily. The feet have well spread toes, so that its weight is evenly spread out, allowing it to walk on floating vegetation and soft mud.
The diet is very varied and includes invertebrates, plant material and even small birds, which it disables with strikes to the back of the head to destroy the nervous system.
They are also very fond of scavenging dead things, and placing out a carcase in view when conditions are harsh - is a good way to see them.
Our resident birds are swollen by large numbers arriving in Britain in autumn over the North Sea, usually under the cover of darkness.
Unfortunately, as they fly low, they tend to hit many obstacles such as fences, power lines and even lighthouses, which disorientate them.
Snipe
Snipe are secretive wading birds of wet grassland and marshy areas.
Their well-camouflaged plumage means that their presence is often overlooked. However, when disturbed, they emit a kind of pathetic squawk like a parrot being squashed, as they depart quickly in a zig-zag flight, supposedly to avoid gunshot.
They are partial migrants, with the UK receiving an influx of birds from the continent during the winter, while our resident breeding birds move to coastal areas.
Snipe use their very long bills to probe and feel for earthworms, leatherjackets and other insects. Young chicks are generally fed on earthworms collected by the parents around the nesting site. Suitable wet soil conditions are therefore a critical requirement.
From April onwards snipe breed on bogs and mosses, pastures with rushes, tussocky grasses and the marshy edges of streams and rivers. Even small, wet field corners can be used. The nest is in a tussock of grasses, sedges, rushes or heather.
Snipe perform spectacular displays high in the sky. Each male, following a circular route, makes a series of power dives during which the outermost tail-feathers are held out at right-angles to the bird's body. Feather vibration in the slipstream produces the remarkable sound known as 'drumming'. It does not however, sound like any kind of drumming. It’s quite unlike any other sound - you just have to hear it.
Once a female snipe is attracted, the male pursues her and dives with wings held above the body while rolling and turning upside-down.
Many breeding attempts fail since crows, foxes, stoats and weasels take the eggs. Trampling by livestock and late flooding are also hazards. Fortunately snipe are persistent breeders and females may produce three or four clutches in the season before rearing young.