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Inspired by his father, the bird artist Donald Watson, Dr. Jeff Watson has studied golden eagles for over 20 years. In addition to his research on the population ecology of golden eagles, Jeff has worked on merlins and hen harriers in Scotland and has done extensive conservation research on a range of endangered landbirds on the Indian Ocean islands of Seychelles. He has written extensively on the golden eagle, including a detailed monograph on the species (see Resources). Currently Jeff is North of Scotland Director with Scottish Natural Heritage, the government nature conservation and countryside agency in Scotland.
In January 2004 Jeff answered a few questions for NATURE about his work with golden eagles:
Can you tell me about the first time you saw a golden eagle?
My first sight of an eagle was, perhaps unusually, a bird sitting on the edge of a large nest in an old Scots pine tree. The female eagle had her back to us as we approached and seemed momentarily unaware of our presence. Her broad powerful shoulders were full of latent power, and as she turned her head I marvelled at the sheer massiveness of her potent beak. Slowly she unfurled her great wings, bounced gently on the springy nest platform and sailed like a fully rigged galleon down below the low branches of the tree, and in complete silence, just drifted out of sight behind nearby trees. The abiding impressions were of size, effortless slow-motion flight, and a simple stealthy silence.
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Can you tell us more about your father and his work? How did your father's work inspire you to study eagles?
My father has made his living as a bird and landscape artist all his working life. He was a great observer of nature, first in the sheer beauty of color and form, but more and more he observed with an enquiring eye to try to understand the life of his subjects. He was a great teacher, impressing on me the importance of careful observation, of recording what you see with honesty, but never losing sight of the aesthetic qualities of birds and their place in the natural world. This blend of scientific observation and appreciation of natural beauty were all important to me as I trained as a field biologist. We lived in rural Galloway in southwest Scotland and were fortunate still to have a good range of birds of prey despite the ravages of pesticides that affected so many populations in the post-war years. The 1960s was a time of optimism for people with an interest in birds of prey, as populations of Peregrine falcons began to recover and others such as hen harriers (marsh hawk in the U.S.) and golden eagles were re-colonizing old haunts after a century or more of merciless persecution. My father took a special interest in the hen harrier, attracted by its grace and as a perennial subject and focal point in his landscape paintings. After nearly 20 years of observing harriers he wrote an impressive monograph in which he combined his own blend of art and science. I loved the hill country of Scotland and it was therefore a privilege in 1980 when I was given the opportunity to study golden eagles full time. This was initially for a five-year period in the Scottish Highlands but has developed into a lifelong study and has given me the chance to observe and write about eagles from many parts of the world. In 1997 the results of this work were brought together in my own monograph on the golden eagle.
How and why has the number of golden eagles fluctuated in Scotland?
Since the early 20th century golden eagles in Scotland have recovered, having reached a low point of perhaps as few as 150 pairs. Now there are over 420 pairs and the population is stable -- confirmed by three national censuses in the past 20 years. There are still threats and the population is yet prevented from reaching its full potential. Although fully protected by law since 1953, eagles in Scotland are still killed illegally each year.
Most man-induced deaths occur through eating poisoned bait, set illegally to control foxes and crows but consumed by eagles, especially in winter when they are great scavengers, feeding on dead sheep and deer and other easy pickings. Poisoned baits are laid by gamekeepers who believe they must control predators on the commercial grouse moors that occur mostly in the drier climate of eastern and southern Scotland. This mortality leaves many gaps in the golden eagle range and is a major factor limiting the expansion of the population south into the border (between Scotland and England) country and to England where only one or two pairs survive.
Apart from human persecution, the fate of eagles in Scotland is determined by land-use practices, and their effect on the eagle's food supply. Populations are most dense in the west of the country where there is abundant winter food in the form of sheep and deer carrion. Here golden eagles occupy territories as small as 18 square miles, whereas in the east they range over areas of 50 to 60 square miles. In summer, eagles need live prey, as opposed to carrion, to feed their growing chicks. Such prey as red grouse, mountain hare, and rabbit are generally more plentiful in the east of the range and consequently the birds here, so long as they are free from persecution, tend to breed more successfully. Typically in the west of Scotland breeding success is around 0.3 chicks per pair per year and in the east nearer 0.7 chicks. Broods of two chicks are not uncommon in the east but very rare in the west.
Two land uses other than grouse moor management influence the fate of eagles in Scotland. In the southwest Highlands large-scale commercial forestry plantations in open mountain country have displaced the favored open-country prey of eagles and led to population declines, notably in places like Kintyre but also in my native Galloway. In the northwest of Scotland there are potential long-term problems resulting from over-grazing of the upland vegetation by excessive numbers of sheep and deer. This has led to loss of heather -- the principal food plant for grouse and hares -- and as a result there is often little other than carrion for eagles to feed upon.
Where else do golden eagles live? How are golden eagles in Scotland different from in other parts of the world?
The golden eagle has a circumpolar distribution in the northern hemisphere, known as a Holarctic distribution, and occurs generally between latitudes 30-60 degrees north. Typically it is a bird of mountain regions, ranging from Scotland and Scandinavia, the Alps and the mountains of Spain, eastwards to the great Himalayas, and with a Eurasian outpost in Japan. In North America it is most abundant in the west with the heartland in the Rockies from Alaska south to Mexico. One population occurs almost at the Equator in the Bale Mts of southern Ethiopia.
In some flat landscapes golden eagles can thrive so long as their prey is plentiful and there is some vertical structure to the vegetation and nest sites are present. For example there are eagles in the flat peatlands of the Baltic where they nest in pine trees in isolated forest stands that are surrounded by open peatlands with abundant capercaillie and small roe deer as prey. It is the size of available prey that is important to golden eagles. There needs to be plentiful food in the weight range of 2 to 6 pounds. This is often provided by species of grouse or hare, as in Scotland, but can be substituted by some unusual prey like tortoises in the eastern Mediterranean, large lizards in North Africa, and even hedgehogs on the Swedish island of Gotland. In the United States jackrabbits are important food, especially in hot desert areas to the south. In Scotland, and throughout much of this range these eagles nest on crags in mountains. Where cliffs are lacking then they will build huge structures in sturdy trees such as pines.
The golden eagle over much of western Europe is one of the larger races, outsized by the massive Himalayan race in which the female can weigh up to 13 to 15 pounds. The smallest of all is the island race in Japan where females weigh it at just over six pounds. The North American race is also rather small, and tends to be darker than the eagles of Western Europe, looking especially black on the front and underside.
Adult golden eagles are more or less uniform dark brown, sometimes paler on the upperside where flight feathers can be bleached by the sun. Juvenile and immature eagles have large white patches on the wings and the tail, sometimes retaining these until they are three or four years old. These dramatic and huge black-and-white flight feathers are used by Native American Indians in their traditional war bonnets. There is a hugely fascinating, almost religious association between some Native American tribes and the golden eagle. In the Tien Shan Mountains of central Asia there is today a strong living tradition that involves men hunting with golden eagles from horseback; here their quarry is the Corsac fox (hunted for its fur), and the antelope (hunted for meat). Some even report these horse-borne eagles catching wolves!
In the film a young eagle was deliberately poisoned. Why do you think this practice continues?
Poisoned baits are used illegally by gamekeepers to control crows, foxes, and sometimes even birds of prey such as eagles, kites, and buzzards. All three are prone to poisoning because they naturally feed on carrion, especially in the winter when other sources of food can be hard to find. Game preservers believe that the decline of grouse numbers (something which has been going on for nearly a century in parts of Scotland) is attributable to the depredations of so-called vermin or pest species.
Although some grouse are certainly killed by birds of prey, it is clear that many other factors are involved, not least the loss of extent and condition of heather as a result of two centuries of heavy sheep grazing. The incidence of deliberate and targeted poisoning of eagles is quite rare, though incidental poisoning is more common, when crows and foxes are the real target. Although illegal, the practice continues because it is undoubtedly efficient and it is often difficult to bring a prosecution with evidence hard to come by in the sparsely populated uplands. Nevertheless, attitudes are changing and there is typically a huge public outcry on the rare occasions that perpetrators are caught and charged. Grouse moor management is, however, big business, and to date the meager fines and low incidence of successful prosecutions are not helpful. In the long run the weight of public opinion will probably be the more effective vehicle for deterring this anti-social behavior by a small minority of irresponsible gamekeepers.
Sightings of golden eagles are rare. How do you go about observing these elusive birds?
In the short days of winter, alone on the hill, hiding from the bitter arctic winds, searching for eagles can be no fun at all. Long periods of frozen inactivity are interspersed with the necessary move to another hiding place, but then only to regain the feelings in numb limbs. And then, a brief window of pale sunlight lights up the world and in that moment, the fleeting image of a distant eagle rounding a far-off hilltop confirms that the big bird is still in residence.
I used to think that patience was the greatest virtue of the eagle watcher -- but in winter I think is more persistence that wins. I have a little rule when pursuing a particularly difficult pair of eagles. I set myself a time, maybe three or four hours, and I just stay there until the job is done, when the birds are located. Then, if nothing shows up after the allotted time, I will always add another 15 minutes, for luck. It is amazing how often the eagle makes its appearance in that "extra time." But there are other days, in early spring when all the omens are good, and a steady hike round two or three eyries reveals many sightings, much activity at nests, and all the promise that is somehow symbolic of the new season. These days are magic, and give you the stamina to take on many more days when the birds are lost in the mountain mists, or just plain cursed!
In the film you mentioned a program that aims to reintroduce the golden eagles in Ireland. Can you tell us more about that program and how it is progressing?
Golden eagles were exterminated from Ireland around 1915. Since then there have been no breeding records in the Republic of Ireland and only very infrequent records of wandering birds from Scotland. In 2000 an ambitious plan to re-establish golden eagles in Ireland was commenced. Over the past three summers some 20 birds have been taken as chicks under special license from nests in Scotland and released in Donegal, northwest Ireland. This area is known as historical eagle country, and before the introductions began much careful work was done to assess the availability of food and nest sites as well as to consult with local sheep farmers. These studies were positive and convinced people that the reintroduction could succeed.
Early evidence from the reintroduction is all very encouraging. Birds have been transported successfully and have been released without mishap. Food dumps have been provided for these youngsters and these have been well used, though independent hunting and ranging well beyond the release site has also occurred. To date there has been only one death amongst the released birds. The attitude of local farmers remains neutral or positive and there have been no reported conflicts with livestock. The project will certainly continue for several more years to give it the best chance of success. It is unlikely that breeding will occur for another two to three years. However, there are high hopes that the first young eagle will be fledged in Ireland well before the end of the first decade of the 21st century. The Scottish population certainly remains healthy enough to contribute to this exciting project -- a national census in 2003 revealed a small but modest increase on the previous 1992 census. Most of the young taken from Scotland are from broods of two where ultimately the second chick would be unlikely to survive.
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