Return of a Native: reintroduction

Despite being protected by law in most countries, sea eagles continued to suffer from persecution and the loss of their habitat. But after the middle of the last century, a new threat became apparent – from toxic chemicals such as organochlorine pesticides (DDT, DDE, dieldrin etc) and, later, from industrial pollutants such as polychlorinated biphenyls (PCBs) and heavy metals. This menace became most prevalent in parts of the Baltic and in Eastern Europe, where sea eagles were once common and soon suffered extensively. These persistent chemicals became concentrated in plant and animal tissue as they progressed up the food chain leading to breeding failures in the topmost predators such as eagles. Some birds even died from lethal dosages.

Various countries instigated desperate conservation measures, such as feeding clean food and captive breeding programmes while, at the same time, they also strived to ban the problem chemicals. Sea eagles had become scarce in many areas while Norway, with low levels of industry and pollution, managed to retain healthy populations. It was obvious that northwest Scotland offered similar opportunities if only sea eagles could re-establish. While the migratory osprey had returned naturally, it seemed unlikely that the more sedentary osprey would ever recolonise without human assistance.

How is reintroduction carried out?

In 1959 and 1968 attempts were made to reintroduce the sea eagle to Scotland but they did not involve sufficient numbers of birds, nor did they continue long enough to guarantee success. So in 1975, the Nature Conservancy Council (now called Scottish Natural Heritage) instigated a longer term reintroduction project. This was based on the Isle of Rum, a mountainous National Nature Reserve in the Inner Hebrides, where sea eagles had bred until 1907. It was also within sight of the last breeding pair in Skye.

Over the next ten years to 1985, a total of 82 eaglets (39 males and 43 females) were imported, under special licence, from nests in northern Norway where the sea eagle population was still expanding. Since the sea eagle often rears twins only one chick was taken from each nest and, such was the density of breeding pairs that different nests could be visited each time.

With generous assistance from RAF 120 Squadron, the eaglets – nearly fledged – were transported swiftly and safely to Kinloss in Scotland, and from there to the Isle of Rum. Installed in roomy cages on a remote shore the chicks were fed a natural diet of fish, birds and mammals, while they completed a statutory five weeks in quarantine. Once they were released food dumps were maintained nearby to supplement the birds’ diet and while they perfected their hunting skills. Even without parental example the young eagles became fully independent over the next few months and soon ranged further afield

Breeding success is achieved

Sea eagles take about five years to mature, so it was several years before the youngsters released on Rum began to form breeding pairs. The first eggs were laid in 1983, but failed to hatch, as did two clutches in 1984. However, in 1985 a pair of Rum birds now established on the nearby island of Mull, successfully reared the first wild sea eagle chick to be fledged in Britain for over 70 years. Progress was slow at first (with only half a dozen young from 8 or so pairs). So between 1993 and 1998 a further 58 Norwegian eaglets were set free, this time in Wester Ross. Momentum gathered and by the twenty fifth anniversary of the start of the project a dozen youngsters were reared from 22 pairs, including the hundredth chick to be fledged in the wild. By 2003 just over 30 pairs were established and a record 26 eaglets took to the wing. A further 19 followed in 2004.