Raptor Tracking

One of the research projects at GGRO that I got increasingly involved with during my internship involved a new and exciting piece of technology called a GSM tracker. Put simply, this is a small device we can affix to a bird. Recharging via solar power, the device will periodically send us the GPS coordinates of its current location, much the same way that text messages are sent cell phone to cell phone.

Of course, if the device isn't able to recharge (for example, if the bird is hanging out underneath dense vegetation or the bird preens a feather on top of the solar panel) the battery will die and we will no longer receive signals. Similarly, if the bird isn't in the range of a cell phone tower, we won't be able to receive the "text messages." Despite these occasional technological hic-ups, however, the technology provides us with a lot of useful information, namely the exact locations of where these birds are traveling. While band recoveries usually give us one location, sometimes two, with these devices, we can track the exact movements of these birds throughout their entire migration (which would be kind of creepy if we were talking about humans…).

I got a chance to see a juvenile, female red-tailed hawk get a GSM device affixed on one of the last days of the research season. The bird is trapped at a banding station. During this process, a traditional falconry hood is put over the bird's head to keep it calm. The device itself is harnessed onto the bird, mimicking the idea of wearing a backpack. The harness is sewn together with dental floss, of all things, because that will decay after about a year, the expected lifetime of the device.

Once the device is secure and we've ensured that it is safe, the bird is released. Each of the GSM-birds gets a name to make it easier to keep track of each of them. The first GSM-bird was named Augusta, and each subsequent birds has had a name starting with the next letter of the alphabet. This hawk was the J-bird, and so the banders named her "Juanita."

After the bird is released, it is a waiting game. And eventually, we started to receive GPS-coordinates from Juanita's device. Juanita flew south from the Marin Headlands, and after only a couple of days, settled into a neighborhood, where she remained for the following month. This map shows the positions of all of the GSM-birds that have reported. Juanita is pink.

Here is a zoomed in version. There's clearly plenty of prey to eat and nice trees to perch on in this neighborhood.

The map can be seen here: http://www.parksconservancy.org/conservation/plants-animals/raptors/research/gsm-tracking.html

So far, eight birds have provided us with interested data-points, all of them red-tailed hawks. And the lesson so far, which further confirms what previous studies of raptor migration have shown, is that there is no rhyme or reason to red-tailed hawk migration in the West coast. It seems that they go where it is most convenient for them to go.