Ornitho-logic

How to Tag a Raptor

Banding a songbird is one thing—birds of prey are quite another.

Roy Dennis regularly risks stitches, or worse, in the line of duty. Attaching GPS trackers to raptors with razor-sharp claws is no easy feat, but Dennis, an ornithologist with 50 years experience, has had plenty of practice. Today, as head of the Highland Foundation for Wildlife in Scotland, he focuses mostly on two protected species in the United Kingdom: Ospreys that migrate across the Sahara Desert between Europe and West Africa each year, and resident Golden Eagles. Both are poisoned and poached, something tags can help detect.

Dennis talks tracking and crime busting with Audubon—and explains why he wishes he’d named some of the birds he’s tagged after celebrities.

How do you get hold of a raptor in the first place?

We tag the chicks in the nest. Osprey chicks are surprisingly gentle birds. They don’t really fight or anything. Now, catching the adult is much more exciting. They are extremely lethal. It’s not just the bill, but the talons in particular. We either catch them in a net near the nest, or with a noose—but that’s about as far as I’d go without wanting to give the wrong people too much detail. When they flap around, they can damage their wings, so once you've got them you hold the birds very securely across the wings to keep them closed: it restrains them without hurting them.

What do you do to avoid being stabbed or slashed?

You have to be careful that they can't get into your stomach or your body. If the bird’s talons get into your body it’s very difficult to extract them, and you’re going to get a really bad stab. You’ve got to work with another person who’s experienced and can hold the raptor while you tag. We also put a falconer’s hood on the bird to keep it in darkness, so it doesn’t struggle. But yes, by the end of the summer your hands are a little bit nicked!

How do you get the tracker to stay on the bird?

The tag itself is like a tiny rucksack: Two cotton tapes come around the shoulder and two come around the back of the wing. When the bird preens, the harness disappears beneath its feathers. The tag itself sits on the back, just behind the shoulders, so when the bird is sitting or flying and the feathers are flat, the solar panel on the top of the transmitter is charged by the sun.

Obviously this device doesn’t inhibit the bird?

They’ve just become smaller and smaller. It was only in the late 1990s that they were small enough to put on a bird. The osprey tags we use now are about 30 grams, and they’re not much bigger than an adult’s thumb. Eventually, after about five years, the tag falls off.

You are, of course, adding something to a wild bird. I think it’s very important that you respect that bird, but also that you ensure that what you’re doing has a benefit for the wildlife itself.

What was it like to fit the first GPS trackers?

We put our first satellite transmitters on ospreys in Britain in 1999. After 2007, when the first GPS transmitters came in, we could follow them every hour of the day and see where they were going, their speed, their altitude. We learned what routes Ospreys take, the time they take, how successfully they crossed the Sahara both ways, where they wintered, and the fact that individual adults go back to the exact same tree each year. The longer you have these tags working, the more you learn.

All that hit at the same time Google Earth became easily available, and I think the Highland Foundation for Wildlife was the first to put up its data publicly. We found that people were much more interested if they were watching a bird with a story and a name.

What about using tags against crime?

Alma, the very first eagle I put a satellite transmitter on in 2007, was illegally poisoned two years afterwards. People had been following her online for two years, tracking her via Google Maps I uploaded to show her progress. No one was ever prosecuted, but I think that bird helped to change the law in Scotland.

When she was killed there was a huge outcry from all these people who had been following her. Suddenly it blew up in the papers. Of course the government was very embarrassed by the ongoing wildlife crime, and some revisions were made to the Wildlife Act in Scotland that made it possible to prosecute landowners for any wildlife crime carried out on their land—even if they didn't commit it themselves. I think that Alma helped to get that in, so the tags have become a deterrent. If you poison illegally, you’re killing a bird that’s got a name.

There’s no doubt, if you give a Golden Eagle a name people really connect with it. They learn more about it, and they get more immersed in its life. You’re raising the stakes by turning these birds into individuals. In retrospect, I think we should have called them all after prominent politicians or celebrities. Imagine hearing, “David Beckham was poisoned today.”

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