Terns
Terns
Terns
Terns choose to breed at Forvie for a number of reasons. Firstly, the Ythan Estuary and the shallow waters offshore provide good feeding grounds – all four species rely on small fish like sand-eels and sprats. Secondly, the raised beaches and marram-clad dunes are good places for these ground-nesting birds to nest, as the eggs and chicks are well camouflaged from predators. Thirdly, the site is relatively undisturbed, so the birds can raise their young in peace.
Disturbance and predation are two of the factors which most affect breeding terns. When terns are disturbed, for example by people or dogs, they take flight in an attempt to defend their nests. The courageous Arctic terns will even strike the heads of intruders with their bills! However, this can leave their eggs or chicks exposed to the weather and to predatory birds such as crows and gulls.
Meanwhile, ground predators like foxes, badgers and stoats can take eggs, young and adult birds, particularly by night. This too can lead to breeding failure and the desertion of tern colonies. Over the years, all four species have fluctuated greatly, both at Forvie and throughout Britain.
Here at Forvie we take measures to control these factors and give our terns the best chance of success. In spring, reserve staff and volunteers erect electric fencing around the main nesting area in order to keep foxes and badgers out. The southern end of the reserve is also closed to the public between April and August to keep human disturbance to a minimum. People can help by viewing the tern colonies from the Newburgh side of the estuary – good views of fishing terns can be had here.
Daily wardening of the tern colonies takes place throughout the season, and this allows us to maintain the anti-predator fencing and record the breeding success of the birds. They don’t always thank us for it though – as far as a tern is concerned, a warden is just another predator, and is duly dealt with. Protective headgear is a must for tern wardens!