Monday, 30 May 2016

Exploring eagles

Dark-phase Booted Eagle (John Hawkins)
At first glance the Booted Eagle seemed in fixed position in the sky, motionless above us. But as we stood to watch it carefully, the bird was anything but static. To maintain its fix, it was performing a multitude of complex manoeuvres. The bird was head-into-the wind and unseen deliberations were accommodating wind-speed and its fluctuations, variations of direction, the lift it gave against the drag of gravity. The result of being stationary whilst airbourne came not through hovering, when birds are flying forward at the exact speed of the headwind, but more remarkably by gliding at the same speed. The bird made constant adjustments to achieve this: slight tilting of the tail, a flexing of the carpel joint on the left wing, a compensatory spreading of the primary feathers on the right-hand wing. The result was a sensation of fluidity, of both the air with its mysterious flows and eddies far beyond our ken, and of how the eagle responded - fine-tuned and sensitive. All the time whilst its muscles made gentle pulls at the bases of its feathers, triggered by a command structure of nerves and synapses, the focus of the bird itself was to the ground. Its head was determinedly pointing downwards, using the remarkable acuity of its vision to search for movement - whatever signal of potential prey.

A day later we were to witness the consequence of such scrutiny. Again a Booted Eagle was fixed poised high above us and, without warning, a singular contraction of the wings instantly changed its shape to that of an arrow-head. So fast was the stoop that it was hard to trace it with our binoculars and suddenly the silence was rent by the stridence of swallow alarm calls. From the Retama scrub just a few metres from where we stood, the eagle braked and rose and it took us a further few seconds to realise that it was carrying away its prize. A nearby sturdy concrete gatepost served as a plucking post and later as we examined the scene, amongst the tussles of body feathers were the unmistakable white-dotted, slender bluish tail feathers of a Barn Swallow.

Booted Eagles are, I think, the most brazen in their hunting stoops, verging on the obliviousness of the foolhardy. I have seen them plunge into the rank vegetation of the Madrid motorway verge, just behind a crash-barrier. Or entering a round-about at the edge of the city of Cáceres, I have been dangerously distracted by the  sight of a Booted Eagle dive into the ornamental shrubs in the centre of the roundabout's island. At times, as we watched Booted Eagles in their static glides, a bird would pull out of a stoop halfway and would jerk upwards to regain its position, just as if it were held by a puppeteer's string.

Perhaps the Short-toed Eagle excels even the Booted Eagle in this command of the air, habitually locking itself at even higher elevation, with strongly barred-tail widely spread. But frequently it lapses into a gentle hover, with its broad wings pawing the air softly as its vision seeks the shape of a slumbering snake.
Raptor Identification course May 2016 (Martin Kelsey)
Our exploration of eagles took the shape of a five-day identification course, focusing on the five eagle species here (and on two of the days we saw all five species), which combined long periods of waiting at advantageously sited viewpoints with serendipity. An example of the latter was our very first eagle sighting of the course: a fine adult Spanish Imperial Eagle standing on a manure heap with a motorway behind her. But it was the longer periods of careful observation, especially of birds in flight, that moulded our thinking about these birds. Thus the Spanish Imperial Eagle was more than the majesty of a dark-plumaged eagle with an emulsion-white leading edge to the inner wing and blond nape. It was a powerful raptor flying on level wing, fixed, determined and resolute.

Spanish Imperial Eagle (John Hawkins)

Golden Eagles, despite their heavier shape, flew with a beautiful buoyancy, gliding with uptilted wings, wavering on a central axis.  And we whooped too as we witnessed the sheer exuberance of Golden Eagles in their somersaulting sky-dance display.

But for me, always, nothing can ever match the exhilaration of the unannounced appearance of Bonelli's Eagles, the gripping combination of place and time. In a dramatic landscape of sheer valley sides, rocks and trees, the bird swings around the spur of the ridge, eye-level and without a flap rises from the valley side to circle three times above us. Then, allowing gravity's pull to almost suck it away from us, we watch this most enigmatic of eagles silently taking its leave as it follows the course of the valley. Gone from our vision, it leaves us speachless.

Bonelli's Eagle (Martin Kelsey)

1 comment:

Oliver Richmond said...

Thank you so much for sharing this and I really enjoyed this. I am a writer focused on career and physical development to spread more issues and tips to develop and works through professional resume writing service. Here is a fact I would like to share with you about eagle.Eagles have unusual eyes. They are very large in proportion to their heads and have extremely large pupils. Eagles’ eyes have a million light-sensitive cells per square mm of retina, five times more that a human’s 200,000. While humans see just three basic colours, eagles see five. These adaptations gives eagles extremely keen eyesight and enable them to spot even well-camouflaged potential prey from a very long distance. In fact the eagles’ vision is among the sharpest of any animal and studies suggest that some eagles can spot an animal the size of a rabbit up to two miles away!