Stopping points for migratory waterbirds
Few migratory birds complete their onerous journey in one fell swoop. Most species will make considered ‘layovers’ along the course of the flyway in which to rest, refuel and seek protection from inclement weather. For waterbirds, wetland habitats are a vital component of this annual return pilgrimage between winter and summer homes.
RSPB Titchwell Marsh and Snettisham reserves, like many coastal wetlands support a variety of migratory waterbird and shorebird species thanks to carefully managed habitats. Whilst some species only use wetlands for part of their lives, others are wetland dependent using these environments for breeding, nesting, raising their young and social interaction.
Why wetlands?
Wetlands provide food for birds in the form of plants, vertebrates and invertebrates. Some birds hunt for food in the substrate, red knot gorge on intertidal invertebrates foraged from Snettisham’s expanse of mudflats. Other species, such as goldeneye and pochard dive far beneath the surface of the water in search of small fish, insects and aquatic plants. Feeding on the water’s surface are dabbling ducks such as mallard and teal.
The variety of food in the wetlands store cupboard is often influenced by water temperature. Too cold and it might not be a hospitable environment for small fish, too warm and food production could cease altogether. Hydrology, including timings of water levels and water depth is another factor that influences aquatic flora either allowing or restricting a diversity of wildlife to thrive. Wetland vegetation provides food, cover from predators and a safe underwater environment for nursery fish. Juveniles feed on the detritus that’s formed by decaying plant matter, these fish then become the primary diet of heron and bittern. Surrounding watercourses that allow fish to swim in and out of adjacent landscapes ensure there is a continued source of food for these wading birds.
In addition to all of these resources that wetland habitats provide for wildlife, they are also an important ally in the fight against climate change. Larger regions act as natural sponges, absorbing rainfall and reducing flooding. Meanwhile, coastal salt marshes provide resilience against tidal surges as roots of marsh plants bind the shoreline. This creates a natural barrier against erosion from wind and wave impact- particularly important in flat coastal regions such as North Norfolk.
What’s happening to our wetland sites?
Despite everything wetlands do for us, more and more continue to be lost, along with the wildlife they are home to. Increasing demand for land for agriculture and development has seen 64 per cent of the world’s wetlands disappear since 1900. In the UK, ecologists estimate that only 10 per cent of the wetlands that existed in Roman Britain still survive.
It is not only us humans that are impoverished and even threatened by the loss of wetland and the natural services they provide. Bogs, fens, freshwater reedbeds, saltwater marshes, lagoons and estuaries all provide habitats for a plethora of plants and animals, including many wetland specialists. Even relatively small wetlands are incredibly rich in wildlife that depends on these watery environments. Habitat loss in these areas may directly result in a loss of birds as they form such a vital link in the chain of waterbird migration.
What’s being done?
2nd February marks World Wetlands Day, the date on which the Ramsar Convention was adopted by 21 nations in 1971. This treaty sets out a framework for the conservation and wise use of wetlands and their resources.
The UK has the most designated Ramsar sites of any country, and East Anglia is home to more than a quarter of those including the North Norfolk Coast, The Wash, large parts of The Broads, and the surviving remnants of the great wetland of The Fens.
This is a great achievement, without which far more of our wetlands would surely have been lost or degraded, but we can’t rest on our laurels- there is work to do if we want to protect our wetlands for the future.
You can find out more at www.worldwetlandsday.org