Saturday 16 December 2017

High hoverer eyes the rodents

A VICTORIAN naturalist, Cork-born Rev F O Morris, records the spectacular fall of a common kestrel (falco tinnunculus) to earth with its clasped prey which promptly scuttled off. The seized mammal was a stoat, or weasel. The beautiful "dapple-dawn-drawn" bird of the poet Hopkins' delight was dead. It had been bitten in the throat.

This was an exceptionally unlucky end for a raptor more often seen hovering over motorways where the verges contain an abundance of small mammals, birds and insects.

My own kes sightings have been few in recent years but I must confess to a surge of déjà vu by a spectacular newspaper photograph during the week of a bird with rat prey over a Dublin foreshore.

About 10 years ago I had watched a kestrel hunting over a rocky breakwater in the same area.In other, more rural, places I have seen patient birds perched on overhead wires or on fence posts before rising to focus on young rabbits, leverets or small birds.

My Bull Island kes, like the successful one in the photograph, was seeking rodents in the rocks above the high tide mark. I had lived in the area for some years. There was constant activity of brazen rats foraging. There was amusement when one rat ran out on the wet foreshore to grab a morsel I had thrown to a hopping grey crow. The rat scampered back to its rocky fortress with the crust in its mouth!

I have been fortunate to have seen Lesser Kestrels (f. Naumanni), a smaller and elegant falcon, hunting in the evenings over old town centres in Spain and, in one place in Portugal, there is a carefully protected colony of the birds in an old convent building.

Irish kestrels have long wings and tails much like sparrow hawks, but with blue-grey head on the male, with chestnut mantle and upper wing coverts lightly spotted with black. The tail is blue-grey ending in a conspicuous black band with white tip.

The hovering bird -- "steady as a hallucination in the streaming air" (Ted Hughes) -- makes shallow, rapid wing beats six times a second, broadly fanning its tail, the wings almost motionless when facing into upcurrent, the forward-set eyes giving stereoscopic vision.

It may be seen descending in stages with further hovering before finally dropping on prey. All this activity quickly uses up resources -- 10 times more energy than from hunting from a fence post -- so the bird is constantly on the look-out for food. Up to 20 rats, mice, small birds, not forgetting insects, may be caught in a day.

Rev Morris relates kestrels swallowing mice whole, ejecting the skin from the mouth in pellets. Using hot water to unravel the pellets later revealed "the entire skin of the mouse as if it had been flayed."

The birds nest where it suits their purpose -- on rocky cliffs, trees, bank holes, ruined buildings, church towers, office blocks and old crows' nests. They don't bother with home comforts and though tree nests may be haphazard gatherings of twigs and feathers, more often than not bare earth or hollow on a stony bed is sufficient. Up to six eggs are laid.

There are about 10,000 breeding pairs here, though the English naturalist Mark Cocker suggests the kestrel as commonest raptor being overtaken by the buzzard.

Sunday Independent

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