A little tern for the better at Chesil Beach
Sally Welbourn looks at the habitat support work being done by Dorset Wildlife Trust for one of our rarer seabirds: the little tern
Published in August ’17
A little tern picks up a little dinner (Debbie Saunders)
Amongst the pebbles and wildflowers of Chesil Beach lies a carefully managed habitat of one of the rarest seabirds in the UK, the little tern. If you listen carefully, despite the near constant wind and waves crashing on the 180 billion pebbles along Chesil Beach, you will hear them with their distinctive ‘chattering’ call before you see them. A fast-flying and graceful bird, little terns are master fishermen; onlookers can see their unmistakable yellow bill as they hover over the Fleet Lagoon before plunging in with precision and agility to catch a small fish.
Fence barriers marking out the little tern colony on Chesil Beach (DWT)
The story of the little terns and their survival in this unique habitat in Dorset is complex and fascinating. These tiny birds, weighing less than a tennis ball, are the subject of much conservation concern; they are the second rarest breeding sea bird in the UK, which has earned them protection under the Wildlife & Countryside Act. With less than 1600 breeding pairs in the UK, they have amber status in the conservation importance category.
However, despite legal protection, it became clear that a conservation management plan was needed for them to continue surviving on Chesil Beach, which is the only colony for little terns in the South West.
In 1997 there were 100 breeding pairs, but none at all in 2009. So to help ensure their long-term survival, the Chesil Little Tern Project was established that same year, led by the RSPB and supported by Dorset Wildlife Trust (DWT), Natural England, the Portland Court Leet, the Crown Estate and the Chesil Bank & Fleet Nature Reserve.
Little terns are expert flyers, hovering over the Fleet lagoon in search of food (Debbie Saunders )
By learning more about the little terns and observing their behaviour, the challenges these birds face, not only as a result of their habitat at Chesil Beach, but also from their own nesting habits, soon became clear: one of the most significant barriers to their survival is their struggle to raise their young. Ten pairs actually bred in 2008, but no chicks fledged. The reason for this is that as ground-nesting birds, they are open to predation, habitat loss and disturbance. Their survival is constantly in jeopardy, sometimes before the breeding process has even begun.
Each year in March and April, work begins to increase the security of the site, led by the RSPB Little Tern Project Officer with a band of over 50 volunteers. First, an electric fence is installed around a large area of Chesil Beach, which is visible from the DWT Fine Foundation Chesil Beach Centre nearby. This helps to keep out predators such as foxes, and also stops humans from unwittingly treading on precious habitat. A bird hide has also been constructed as a base for volunteers to carry out a 24-hour watch on the little terns between May and July, to scare away predators and to closely monitor their behaviour and keep track of their population numbers. In 2016, 1200 hours of volunteers’ time was given to the surveillance of the little terns. Other tricks to keep avian predators away include ‘anti-perching’ devices, where used plastic bottles are attached to fence posts and other perching sites: simple but very effective! This year, trained wardens are also using lasers to deter predators; no harm will come to the public or animals, but it is enough to distract a hungry bird.
Ringed adults on a buoy (Angela Thomas)
Perhaps the biggest revelation from monitoring the little terns was the finding that before 2013, a very high proportion of the eggs were not hatching. It was suspected that this was because of the cold location; the wind is always whipping around Chesil Beach, even in the summer. It was also clear that the birds were nesting on shingle and not using any nesting material; hatch rates were just 23% on shingle.
So the wardens created sand patches to increase insulation from the elements, which in turn dramatically increased the proportion of eggs hatching to 90%. Installing sand patches is now a regular part of the project, with the majority of birds selecting sand patches to nest on, and the RSPB have a special licence to allow them to place sand under any nests established straight onto the cold and draughty pebbles.
A lot of planning is done in anticipation of the little terns arriving. As the area is prepared for them, they are on their epic journey from West Africa to their final destination at Chesil Beach. They arrive in late April, and June is the peak time for breeding. After a courtship involving aerial displays and offerings of fish by the male, the female lays two or three well-camouflaged eggs. The chicks will hatch 18-22 days later, and grow quickly, practising their fishing and flying skills, before they all embark on a 2485-mile trip back to Africa. Weather can affect the duration of their stay – if the weather is bad, this could extend their season and they could stay until September – although they usually leave in August.
Perfectly suited to their pebbly home, little tern chicks blend into the background (Morgan Vaughan)
There is something about the little terns which fascinates visitors, who return year on year to witness the progress of these wonderful birds. The odds are stacked up against the little terns in many ways, but the work and passion which volunteers, wildlife groups, local landowners and visitors have for them has seen a huge turn-around in their survival success, with a staggering 330% increase in their breeding since 2008. In 2015 there were 36 fledglings and in 2016 this number nearly doubled to 71.
It is hard to imagine now that little terns could have ceased visiting Dorset altogether, and it is thanks to careful conservation management techniques introduced by the RSPB and the partnership project that Chesil Beach is now one of the most successful little tern colonies in the UK, increasing in size and productivity all the time. The hope is that eventually the colony will recover enough to be self-sufficient and the need for extra protection and intervention will decrease over time. Until then, under the watchful eye of wardens, little terns will continue to be protected and taken care of for the enjoyment of people and the benefit of wildlife.
Find out more about the Chesil Beach Centre and the little terns at:
www.dorsetwildlifetrust.org.uk/littleterns and follow @little_tern17 on Twitter for all the latest news and updates about the Chesil little tern colony. You can also view the little terns with binoculars from a viewing area at the Chesil Beach Centre.
