Observation of Sparrowhawk attack

[davidbale]

I have often observed Sparrowhawk plucking their prey and leaving a pile of feathers - sometimes in my own back garden. I have, however, never before witnessed the actual moment of attack.

Last week I was watching a female blackbird feeding on my lawn. Suddenly a female sparrowhawk appeared and instantly overwhelmed the blackbird, pinned it down with her talons, so that the blackbird was facedown, as it were, with a pair of claws on her "shoulders". The sparrowhawk stood motionless and erect over the blackbird for a couple minutes, while the blackbird first kept trying to open and close her bill before seeming to expire. The sparrowhawk maintained her steady grasp, like a strangler or someone smothering someone else with a pillow. She didn't use her beak at all throughout the whole attack, but remained still for another couple of minutes, pinning the blackbird to the ground. Then, to my surprise, the "dead" blackbird made a spirited attempt to wriggle free! The female Sparrowhawk simply adjusted her grip and pinned the blackbird down more firmly. For a second time, the blackbird appeared to have died. After a further minute or two, the Sparrowhawk raised her left claw about an inch and appeared to administer the coup de grace (like a killl in a bullring) by plunging the spur of her left claw firmly - but almost unviolently, in a matter of fact way - into the blackbird's body. Still the Sparrowhawk didn't move - just looked defiantly at me for another 2 or 3 minutes, before, as suddenly as she arrived, she whisked the body of the female blackbird into the air and flew off, carrying the now dead female blackbird off with her.

Throughout, there was no plucking of feathers and no contact of any kind between the bill of the sparrowhawk and any part of the blackbird. Nor had there been any scratching at the blackbird with the sparrowhawk's claws. Instead, there had been an almost struggle-free confrontation in which the Sparrowhawk remained almost motionless throughout, simply waiting for the pinned-down blackbird to expire.

Yet although there was no sign of any loose feathers throughout the attack, a large quantity of feathers was released as the sparrowhawk departed. I gathered the feathers up. They were all small grey feathers from the blackbird's breast. There were no flight feathers or larger feathers of any kind. Yet there were hundreds of the tiny downy feathers. They more than half filled an empty litre ice-cream container. I weighed them - they weighed 3 grammes.

And I'm certain none of these feathers were plucked.

Does anyone know how the feathers were lost? Was it shock? And could many of the findings of feathers that are usually ascribed to plucking by a sparrowhawk in fact be the site of similar "pinning-down" attacks to one I observed last week?

[RKB]

You did well to see the stabbing action of the hind claw - that is the general way in which a Sparrowhawk kills its prey. It would be daft to put your head/beak near a live victim that can still struggle.

Blackbirds can easily lose their feathers, and it has been suggested that this is a defence mechanism called a 'fright moult', by shedding a mouthful of feathers and and then making an escape while the predator is confused.

[Littlesparrow]

our local Sparrowhawk attacks with lightening speed and a couple of times all you see is a brown flash and then a few feathers floating down on the air like a cartoon scene. It is far too quick for the hawk to have plucked the feathers out and i suspect some of the small birds are caught on the wing.

[Jonathan]

If you watch a sparrowhawk on a kill very carefully you will see it continually tenses up it's feet - similar to a man clenching his fists. This drives the inner and back talons of the hawk deep into the living prey, hopefully piercing some vital organ. The other two toes on each foot are relatively weak and are used for holding, etc. Falcons kill differently, they sever the spinal chord in the neck using the tomial tooth on the upper mandible of their beak.

The clenching of feet in accipiters seems almost involuntary at times. I've held many spars and gosses on my fist, when they're hungry they continually tense up their feet - it can be quite alarming if it's a huge female gos and you're wearing a thin leather glove! In outdated falconry parlance a bird in this state of eagerness is said to be 'in yarak'.

Cheers
Jonathan

[RKB]

Originally Posted by Jonathan

Falcons kill differently, they sever the spinal chord in the neck using the tomial tooth on the upper mandible of their beak.

Sparrowhawks have a tomial tooth too, so is this a hard and fast rule?

[Acipiter]

At some kills you may well have found some flight feathers, that had been removed as well, If you had not have been there, you may well have found this. They normally eat it where they caught it, if not disturbed.

[Jonathan]

Originally Posted by RKB

Sparrowhawks have a tomial tooth too, so is this a hard and fast rule?

Isn't it simply the tomium, the cutting edge of the beak, in sparrowhawks:

http://www.davidnorman.org.uk/MRG/Fa...20x%20600).jpg

Peregrines, for instance, seem to have a much more defined 'tooth':

http://whyevolutionistrue.files.word...pg?w=313&h=570

In my experience spars sometimes remove the head of smaller prey, but the prey's usually dead when they do it, I can't recall seeing one grip the neck of a bird and actively seek the point to deliver the coup de grace, so to speak. Peregrines often take several attempts to find the right point to sever (or crush perhaps) the spinal chord. I've seen a peregrine kill an adult drake mallard using this method - quite a feat!

I'm sure you've seen such footage before RKB but for anyone who hasn't seen a peregrine kill using it's tomial tooth, this footage shows the falcon dispatching the bird around the 50 second mark.

YouTube - Night-time Hunter

Cheers
Jonathan

[Acipiter]

Removing the head is usually done by the male, for the female in the breeding season. S/hawks kill as you said before Jonathan, and eat while the bird is still alive.

[Acipiter]

The curve in the upper mandible is called a festoon in accipiters and is not used for killing as such.

[Jim Ford]

Whilst we're on sparrowhawks:

Some years ago I found a dead sparrowhawk in a wood (can't recall whether it was male or female). It was completely unmarked, except that the head was missing and a meter or so away. The head was also unmarked, and still fresh as the eyes were bright. I've never had an explanation as to how it met its end. There were no wires around and no one else in the wood at the time.

Jim