Julie Fukuda:
>A coworker and I are wondering if anyone has ever actually witnessed a bald
>eagle being pulled under the water by a fish. Is the instinct to hold on to
>a catch that strong?

I've heard of this with Osprey, but don't know how reliable these
stories are.

However, the mechanics of a raptor's foot are such that they can have
difficulty letting go of things if they can't straighten their
legs. For instance, if you're ever footed by a raptor when, say
banding, it can be almost impossible to pry talons out of your
(typically) hand unless you first straighten the leg. When
bent, there's tension on the tendon running down the tarsus
to the toes which keeps them clenched. Not only is this
lessened when the leg is straightened (i.e. it physically
can't clench as hard) but this also causes the bird to
relax the muscles attached to the tendon in many cases. I
don't know if this is due to instinct or reflex. If a person
jerks in this situation, the bird will clench up and I would
think this is simply a reflexive action and that the bird
has little control over it.

So it's not hard to imagine scenarios where an osprey or eagle
might find it physically difficult to let go of a struggling
fish too big to fly off with. I don't know if they ever actually
get into trouble to the point of drowning, though.

Here's another trivia question. Osprey always emerge with the
fish held head-first, one foot in front of the other "surfer style".
Do individuals always put the same foot in front? If so, are
there "right-footed" and "left-footed" Osprey, or are all the
same?

Happy New Year!

- Don Baccus, Portland OR <donb at rational.com>