Guest blog by Laura Smith, RSPB Portmore Lough warden
Portmore Lough, a hidden haven for nature near Aghalee in County Antrim, is home to a thriving colony of common terns.
These amazing birds, nicknamed ‘sea swallows’ due to their long tails, migrate all the way from Africa each spring to breed at the reserve. Despite their name, numbers of these birds are falling and they are now amber-listed (of medium conservation concern) in the UK and Ireland – making Portmore Lough a really important place for the future of the species.
The terns nest and raise their chicks on man-made floating rafts on the lough. The rafts are covered with gravel and pebbles to make them look like the shingle islands that the birds would naturally make their nests on. Last year the two rafts were full to bursting, with 75 pairs of terns jostling for space alongside around 100 pairs of black-headed gulls!
We desperately needed more space to allow the colony to grow and, thanks to support from the Challenge Fund, we’ve now been able to install a fantastic new raft. This spring, after flying thousands of miles, the terns will have an extra 32 square metres of prime real estate to nest on!
Our dedicated volunteer team worked very hard moving three and a half tonnes of gravel from the car park, all the way across the reserve and on to the raft using our special vehicle with low-pressure tracks to stop it sinking!
After evenly spreading out the gravel, we placed roofing ridge tiles onto the surface – these will provide the chicks with somewhere to shelter from the elements. The new raft, which is made up of sturdy interlocking plastic blocks also has a wooden barrier all the way around to prevent chicks from falling off into the water!
To ensure the chicks have the best chance of survival, it’s very important to make sure predators like mink can’t climb onto the raft. A wide plastic board was attached to the top of the wooden barrier around the raft, creating a smooth, slippery overhanging ‘shelf’ that should prevent mammals climbing on to the raft from the water. This is the first time we’ve tried this technique and we’re hopeful it will be an effective way of protecting the birds without the need for electric fencing.
Finally, it was another huge team effort to tow the raft out onto the lough and anchor it. It took a bit of manoeuvring, but the raft is now securely in place in full view of the waterside hide.
The common terns will return to Portmore next month and we’re hopeful this will be the best breeding season yet for this marvellous migratory bird.