Colours of Wildlife: Spotted Eagle
Created | Updated Oct 7, 2012
Spotted Eagle
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
Today’s picture is of a Spotted Eagle, Aquila clanga. This large eagle species is actually not very common here in Africa. It is a migrant from Europe and Asia, coming to northeastern Africa. It hasn’t been recorded from South Africa as far as I know; in the rest of Africa it might be underrecorded. My painting of it shows it sitting in a Fever Tree, Acacia xhanthophloea which would be quite familiar to South African folks, and also occurs up in East Africa. I’m indebted to Wikipedia for most of the information in this article.
This eagle is sometimes called the Greater Spotted Eagle, to distinguish it from its closest relative, the Lesser Spotted Eagle, Aquila pomarina. In fact, this species, like many I’ve featured in this column already, is inappropriately named. The adult eagles are not spotted, but are brown, the head and upper wings being very dark, with a lighter patch on the wings and a white V-shape on the upper tail coverts. Juveniles have cream-coloured spots all over their wings and backs, these gradually diminishing as the bird matures. The individual in my painting is therefore almost but not quite grown up.
This is a medium-sized eagle, usually 66-71 cm (26-28”) in length, with a wingspan of 160-180 cm (about 5’3”-5’11”). As in many other eagles, the females are larger than the males, large females weighing up to 3.2 kg (7.1 lbs).
The breeding range of this species stretches from Eastern Europe through the entire length of Russia and northeastern China up to the eastern Asian coast. It inhabits wooded country and hunts mostly small mammals and other ground-living prey. They are territorial, except for youngsters who stay with their parents for a while after they fledge, until they are fully mature.
But when these eagles migrate to their wintering grounds, they are more social and accepting of other Spotted Eagles as well as different raptors. On migration they will associate with kites, Steppe Eagles and other birds-of-prey, sometimes forming small flocks. Apart from their regular migration routes, some vagrants or drifters can sometimes be found in regions they usually don’t occur in. It is still not clear just how prevalent this species is in Africa. Most spotted eagles migrate to southern Asia or sometimes southern Europe. In Africa, confusion with the much more common Lesser Spotted Eagle may pose a problem, as well as several other large brown eagle species, such as the Tawny Eagle, the Steppe Eagle, or the smaller Wahlberg’s Eagle.
In evolutionary terms, this species is clearly most closely related to the Lesser Spotted Eagle. The two species diverged from a single common ancestor that lived perhaps about 2 million years ago somewhere in central Asia. This mutual ancestor in turn diverged from an even older common ancestor with the Indian Spotted Eagle, Aquila hastata, around 3.6 million years ago. It would do well to bear in mind that our own forebears at that point were still at the very much ape-like Australopithecus-level. I try to encourage people reading these articles to think more in evolutionary terms. The point to take home is that about three and a half million years of evolution went into distinguishing these three very similar species of eagle. The other eagle species are all more distantly related and therefore separated by even greater evolutionary periods. So there will be a common ancestor with for instance the Steppe Eagle as well, but this ancestor would have lived many more millions of years ago. Our present supposition is that there could always (in theory – in practice, only if we develop truly effective time machines) be a common ancestor found between any living thing and any other living thing on this planet; the more recently this common ancestor lived, the closer those two things are related to each other. In the absence of time machines, detailed studies of genes along with models of the historic rate of genetic changes can give us an idea how much evolution has happened. So, as far as we can tell, modern humans for example have all diversified from a common ancestor living about 100 000 years ago, giving you an idea how closely related we are to each other, compared to these eagles. The full diversity of different human types that now exist therefore represents 100 000 years worth of evolution inside our species. (Also it might interest you to know that the majority of this diversity exists mainly on the African continent, rather than between African and other peoples. The deepest division, going right back to that 100 000 year-ago point, is between the Khoi-San peoples of southern Africa, and all other humans in Africa as well as elsewhere.) But the difference between Greater and Lesser Spotted Eagles represents two million years’ worth of evolution, twenty times as much as this! I consider it crucial for people trying to understand biodiversity to think in terms of evolution and the vast periods of time over which it has been working.
As we study genes more and more and start getting a better idea of true evolutionary relationships, our systems of classifying and naming living things are due for a shake-up. This eagle, presently still classified in the genus Aquila along with many other what we would consider typical large eagles, such as the Golden Eagle of Eurasia, might be due for a reclassification. It might turn out to be more closely related to more tropical eagle species like the Long-Crested Eagle, Lophaetus occipitalis. Alternatively it might warrant a genus of its own, along with the Lesser and Indian Spotted.
When we consider how much evolution the Greater Spotted Eagle represents, along with its two closest surviving relatives, we can appreciate the importance of conserving it. And it does need our efforts: at present it is estimated to number less than 4 000 breeding pairs in the entire world. Despite its wide range, it is vulnerable to habitat degradation and destruction and human disturbance during the mating season. There is much we still don’t know about it: its precise migration patterns, and details of its ecological relationships. This species sometimes hybridizes with the much more common Lesser Spotted Eagle.
