Monday, October 19, 2009

Kestrel Gone Wild?

Friday at Marshall Mesa I was treated to a bit of good old fashioned aerial mobbing. Mobbing is generally how smaller and more maneuverable species keep predators out of their territory. It is noisy and full of aggressive, showy, displays intended to let the larger predator know that whatever it had been thinking of doing will not be worthwhile. Think of it as the equivalent of professional wrestling in the animal kingdom - there is a lot of posturing and chest thumping, and in the end a winner emerges, but nothing really changes and odds are the entire scenario will be revisited shortly. Unlike wrestling, these interactions are truly captivating, and not something you feel dumber for having watched.
Can you see a difference between the Kestrel above and the one below?

The show was great, if a bit distant for watching as I stood on the ridge. I was confident that the two birds mobbing the Red-tail were Kestrels, but as I only had my camera with me as I watched I wanted to double check the stills when I got them downloaded. I was intrigued by what I saw when I had more detail in a zoom.

One of the two Kestrels was sporting a Jess!

Jesses are what handlers use when moving captive birds between cages, think of them as bird feet leashes.
Kestrels are used commonly by falconers, but I didn't see anyone in the area. I was given a bunch of food for though after seeing the jess. Did the one bird "go wild" and pair up with another of its species? Do individuals that are being trained to hunt by falconers go through an apprentice period where a jess is left on the bird as it is flown with a more experienced, non-jessed bird? If the birds were being flown by a falconer, is it typical behavior for them to locate rival predators and drive them away? Is someone out there missing their Kestrel?

More questions than answers, as is typical when observing nature, but then I find that to be a big part of the fun.

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