Rashkavar wrote:Apparently there's something about the talons of a Bald Eagle (not sure if it's all Eagles or even Raptors in general) that locks them into position when they close around prey. This is generally beneficial as said prey is often still alive for at least a few moments after being grabbed, and its thrashing might allow it to escape if they were just clasped normally.
The tendon that connects to the talons, and a sheath the tendon runs through, have interlocking surfaces. This lets the bird maintain a strong grip without having to hold its muscles taut. It can release its grip by loosening the sheath, which is "locked" when the controlling muscles are relaxed.
It's not just raptors, though. All the perching birds have the same structure. They grab a tree branch, and can then relax their muscles while the locking tendon keeps a strong grip. This is how they can sleep while perched, and is also why you'll occasionally see a dead bird hanging upside-down from a branch or a power line; if they die without actively letting go, they'll hang there until the tendon and sheath decompose enough to fall apart.
But this also means that the eagle in question has to land before dropping its meal. (No idea how the mention of a dropped branch intended for nest material works - I'm guessing it has to do with how tightly it closes the talons.)
This is untrue; there is nothing in the tendon-locking mechanism that requires them to be on the ground to disengage it. Raptors can drop prey mid-flight, sometimes with interesting results
. One raptor will often harass another in mid-air to get it to drop its prey, so the harasser can pick it up instead. And some will drop prey intentionally to kill it, or to get it out of its shell (turtles, etc).
Anyway, this talon gimmick can be problematic - I know of at least one case in which an eagle caught a fish that was too heavy for it to fly with. And remember, it needs to find land so it can let the fish go...so the poor bird gets to swim back to shore. It was a rather sorry looking creature by the time my Dad saw it.
This is true for the wrong reason: eagles can swim, in case they try to take a fish too large to fly with, or one strong enough to swim down while the eagle is holding it. But it has nothing to do with when they can unlock their talons.
That said, don't take this as gospel. My father could easily be misinformed as to the reason this particular eagle had decided to go for a swim. I'm pretty sure this story predates the days of easy fact checking via wikipedia.
It was fairly close, even without wikipedia.