Rebecca E. Koch
Assistant Professor
University of Wisconsin-Stevens Point
CATCHING A FLYING OBJECT: Capturing songbirds
While this project relies primarily on observations of banded birds, birds must be caught at least once in order to give them these unique identifiers. I also collect basic measurements like the bird's body size and weight, take pictures of colored feathers, and sometimes collect a tiny blood sample for DNA analysis (using about the same technique as we use a finger prick for a drop of blood).
I use two methods to capture house finches:
Mist nets
These are the most widespread tools used to catch birds. Mist nets are made of a fine mesh of webbing arranged into rows of loose pockets, held spread between two poles. The nets are of such fine material that they can be difficult to perceive, and birds gently impact the net while in flight, becoming wrapped up in the loose pockets of material. I keep an eye on mist nets at all times so that when a bird becomes caught, I can quickly untangle it and prepare it for measurement and release within minutes. The risk of injury to birds during mist netting is vanishingly small, and it is a technique used worldwide for both birds and bats.
While birds caught in mist nets can look hopelessly tangled, the nets are well designed to hold birds just long enough for careful extraction. The American goldfinch pictured here was out of the net in less than 30 seconds, despite his best efforts to grab on to the net with his feet!
Birdfeeder traps
These ingenious cages were designed decades ago by scientists hoping to take advantage of house finches' love of sunflower seeds. Essentially, this trap is built out of a cylinder of hardware cloth, closed at the top and bottom, with short narrow "tunnel" entrances near the base of the cylinder. These tunnels have perches facing outside of the trap, enticing birds to land and take a look. Then, finches creep through the tunnels to reach a birdfeeder placed in the center of the trap. The inward-facing tunnel shape without an inside perch makes it difficult for many birds to orient and navigate their way back out of the trap from the birdfeeder. When a bird is inside the cage of the trap, I can simply reach in a trap door on the top and pull out the bird!