Yesterday was a great day of Canada goose banding with Mikal Moore from Washington Department of Fish and Wildlife and a motley band of volunteers. This is an annual event and the goal is to be able to get some idea of the movement, site fidelity (e.g., how partial the birds are to certain geographic areas from year to year), and survival (e.g., how many years do they live?). The volunteers represented several walks of life-- waterfowl hunters, kids, and government and tribal biologists. The common thread was a love for waterfowl and concern for the health of their populations. Oh, and also a lack of aversion to goose poop. There's no avoiding it (or them voiding --it!) and you can't blame them since they're scared and just ate breakfast.
So, the way this works is that we break up into teams-- some on the water in boats and some on shore with lightweight net panels. At one location we simply constructed a funnel of panels and herded the birds into it. At other locations we herded the geese onto the grass and surrounded and enclosed them with panels. Why didn't they fly away?? Anyone? Anyone? ... well the key is that at this time of year in Eastern Washington, Canada geese can't generally fly because either they are molting adults or they are goslings that haven't grown in their flight feathers completely. There were a few exceptions but by and large, none of the birds tried to fly. This is very different from trying to capture most any other birds since most species of birds, outside of waterfowl, tend to molt their feathers gradually so that they can sustain flight for predator avoidance and foraging. Geese get away with it because food is abundant and they can use the water itself to avoid ground-based predators and it's edge vegetation (or diving) for protection from aerial predators.
The next step after capture is to determine gender and age of each bird. I got this duty. It's a dirty job, but somebody has to do it. It's not as easy as you might think. I usually kneel on the ground with large birds, I place their head under their wing to help calm them, and I place their body between my thighs with the tail pointing away from me and the bird on its back. Then you close your mouth and attempt to pinch open the bird's vent (be sure to perform these two steps in this order just in case the bird lets loose!). What you are really looking for is a small projection on the floor of the cloaca, which is the avian equivalent of a backside. It's called a cloaca because there's only one hole to handle liquid and solid wastes as well as eggs or sperm. The small projection will be larger in boys than in girls. In the males, the projection enlarges and everts during mating (essentially "darts" out during cloacal contact and enters the oviduct of the female-- if you have a strong stomach, check out http://www.youtube.com/watch?v=qwjEeI2SmiU for a visual demonstration of this function). Make no mistake, though, these birds were not happy to show us their, er, tackle so we kept the experience brief and "to the point." Aging is easy this time of year since young birds have dirty looking chin patches and usually had fuzzy down sprigs on their necks while adults had clean white chin patches and no down. You can also look for tail-tip notching and the shape of primaries (outermost wing feathers) to help in determination.
Once the birds were aged and sexed, they were banded and recorded. In some cases, biologists will also collect morphometrics (measurements) and record these as well. The leg band is a federal band (US Geological Service Bird Banding Laboratory) and has an address and 9-digit unique number. In some cases, geese already had bands and/or neck bands as well. Neck bands are wide white plastic collars that have large letter/number combinations on them for easy spotting with binoculars. Leg bands cannot be read from any distance away and certainly not while the birds are swimming. So, neck collars are used where the birds are being regularly monitored for specific studies. With birds that were already marked, their numbers were recorded and they were sent on their way. Small goslings were also given a break from scrutiny and allowed to rejoing their parents immediately.
In no time flat, we had marked some 100 geese from 3 sites around Yakima. Volunteers are still welcome for some of the other sites. If you'd like to get involved or learn more, contact Mikal Moore (Waterfowl Biologist for WDFW, Ephrata office) at Mikal.Moore@dfw.wa.gov. It's great, messy fun!