Lately, I have been tracking the dispersal of fledgling Ferruginous Hawks. In theory, what we attempted to do was to take young birds out of the nest, fit them with a backpack bearing a radio transmitter, and put them back into the nest. This is a good idea in theory. The reality of the situation is that there is only a very tiny window of time in which a hawk is in the nest and about to fly but not yet actually flying. Even if they are still in the nest, they are probably just waiting for an excuse to try out their new wings, and your approach is a perfect reason. We can’t put the backpacks on birds that are too young, so we did the nest best thing. We ran down flighted birds.
The technique we ended up employing was to spot recently fledged hawks as they loafed around near their nests and then bolt after them. Their flying skill at this stage usually only permits them between about 500 meters and a kilometer before they begin losing altitude. If one is alert, it is possible to gather them up as they make their landing. Sometimes the babies flew away majestically laughing at our feeble attempts to run after them, but often we were successful.
Our success is due in large part to my field partner. He is a man with a truly accipiter-like disposition. By this, I mean he possesses both the speed and single-minded desire to chase after anything that flaps fitting of a forest hawk. I had one or two good runs on my part, but I can do nothing in comparison to this man, known by some as the Destroyer. I was able to make an important contribution, however. My role was to determine where the bird actually WENT, and to determine if the bird was, in fact, a ferruginous hawk. The destroyer is known to chase down red-tails and even ravens on accident, and could probably be trapped using a pinecone with feathers attached. I am serious when I say my partner was a human accipiter.
Once the birds are tagged, it comes down to tracking them. The VHF style transmitter in their backpacks is the classic style radio telemetry tag. All it does is send out a pulse at a given frequency. This is my kind of technology. Simple. After spending so much time messing around with satellite transmitters, remote data downloading stations, and total technological meltdowns, the radio telemetry was a relief. There is really only one available control on a radio receiver, and that is the gain. This just adjusts the sensitivity of the receiver. Using this a person can determine everything they really need to know: the relative distance on the bird, and direction of the signal.
Of course, because the University here can never leave anything simple, airplanes and horses and a whole morass of fancy antennae and equipment have come into the picture. The technology is still simple, but now there is an AIRPLANE and a lot more geometry. Since, you won’t see the bird from the airplane, you instead take a bearing on the bird from multiple points. Where the hypothetical lines pointing towards the bird would cross should be the location of your bird. So as glamorous as doing science from a Cessna might seem, keep mind that both math and vomiting are also happening concurrently.
What I have learned from all of this is that life is difficult when you are a young hawk. It takes more than a sharp bill and talons to get by in the world.
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