Greetings from the DC area! … Pictures (and other content that I want to post) have slowly been piling up, so I want to spend at least a few minutes of this fine Sunday morning making at least one post describing what we’ve been up to.
The first ten days with Nestwatch have been kind of an “orientation” — getting to know your coworkers, filling out lots and lots of paperwork, picking up vehicles, and getting practice with mist netting and bird banding. We even had our first and second real Nestwatch visits this week! More about that later.
Although I’ve volunteered as a bander at the River Bird Observatory in 2010 and 2011, I only had time to band once or twice a week, and processed only about 60 birds total (over the course of two banding seasons). Also, before this summer, I had never set up or taken down mist nets before (I had only open and closed them). While it’s not difficult, there are a lot of details you have to pay attention to in order to make the process go smoothly. (Since the nets are so thin and light, you have to be mindful of how you bag them up, or else they can get “tangled” — not knotty necessarily, but not able to unfurl in a “smooth and orderly” way.) … Anyway, I feel like I’m getting a lot of useful little additions to my bird-handling skill set.
Today I want to post some pictures that show how we band birds.
Set up Mist Netsts
Most bird banders use nets to catch birds. These aren’t ordinary nets, though — these bird-catching nets are nearly invisible nets that are strung across two poles. They are like a large rectangular hair net, but the mesh is fine like spider silk. The nets are strategically placed in shaded areas, or next to vegetation, in order to help conceal them. These fine, lightweight, nearly invisible nets are called mist nets.
Ideally, you set them up (or open them) just before dawn because (1) the nets can’t be seen because it’s still dark, and (2) dawn is when birds are most active.
Here’s a picture of our team setting up some mist nets on the hill just outside the Smithsonian Migratory Bird Center:
Sticking a mist net pole into the ground — setting it up in a lane where two cardinals are nesting:
After the net is open, you have to “clean it up” and make it look invisible by plucking out the wrinkles and debris:
After you set up the mist nets, banders usually retreat for 10 – 20 minutes and wait for birds. Birds will, for the most part, avoid the area if there are people lingering there.
An Outdoor Laboratory: Tools of the trade
Nestwatch banders band birds outside. Here’s the kit we use:
I think most of the kit is pretty self-explanatory. Still, I’ll try to find a photos of the kit in use.
1. Remove the bird from the mist net:
2. Put the bird into a cotton drawsting bag – this protects it and calms it down. (Sorry, I forgot to get a picture of the bag!).
3. Weigh the bird. (We measure the y bird in the bag, and then remove the weight of the empty bag to calculate the bird’s weight.)
Birds are pretty light. Just for fun, some weights of birds:
4. Prepare and apply the bands:
Each bird gets a different sized band; photo from NationalBand.com
American robin with color bands – I actually saw him by the national mall, not by the zoo, just yesterday! I’ll have to go to this website and report him
The above robin has white over pink on its left leg, and aluminum over pink on its right leg; this would be notated as W/R, A/P.
5. Measure the wing chord (shoulder to end of first primary), tail length, and tarsus (leg).
Measuring the tarsus – the “lower leg” on the bird. A bird tarsus is actually a fusion of several foot bones that currently still remain unfused on other animals (example: tarsals and metatarsals) so is sometimes considered part of the foot of the bird, and not the actual leg
What most people think is the “knee joint” is actually more like an ankle joint. The knee joint is actually tucked up close to the bird, under its feathers (#7):
The tarsus is a good indicator of body size, since weight can fluctuate depending on how much the bird has eaten or if it’s carrying an egg.
Usually, to get an accurate measure of the tarsus bone, we have to gently bend the toes (to see where the tarsus bone ends, and the toes begin). Sometimes, the toes are too scaly to bend; scaly feet are a symptom of avian pox. Here’s a picture of an American Robin with a case of pox.
6. Check for fat – When most people take a vacation in a foreign country, they ride in a big jet and enormous amounts of fossil fuels. When birds journey to a different country, they use a little pair of tiny wings and a store of fat (that must be constantly refilled along the way at “migratory stopover sites” — like your backyard). We want to check how full the bird’s “fuel tank” is, and we do it by blowing into the groove right below their neck (which is where the furcula, or “wishbone”, is) and checking for fat pads. We rate the fat from 0 (no fat) to 5 (bulging).
Migratory birds are constantly burning through fat, and so usually have no fat pads (or trace amounts).
7. Check for a brood patch – The brood patch is an area underneath the bird that doesn’t have feathers; instead of feathers, there is a patch of exposed skin which is used to transfer body heat to eggs (skin to egg contact).
The presence of a brood patch usually indicates a female; it also means that the bird is sitting on eggs… it has nest somewhere!
If we find a swollen cloaca (the “hole” out of which birds defecate and copulate), we have a male bird in breeding season. Females rarely have such swollen cloacas. This guy has a pretty good blog entry about how cloacas can be used to determine the sex of birds.
8. Write down and double check your data. Include notes about plumage, eye color, or any other notable features of your bird.
9. Release the bird!
Here are some birds we captured/banded this week:
That’s it for now. Writing about it helps me remember the process, but maybe it has taught you something, too. (I really want to write another post about why we do bird banding, but that post is going to require a bit more research and time than this post did.) Next week, we are going to practice getting mist nets up and down perfectly (without using stakes or ties) and get our methods critiqued in a sort of “banding bootcamp”… and I can’t wait. (If only all examinations were this useful/fun.)
Anyways, I hope you enjoy learning a little bit about the bird banding process, and thanks for reading!