To determine how a bird is responding to its surrounding environmental conditions, it must be captured. Mist nets are fine black nets made of nylon. They come in a variety of lengths and degrees of fineness. Out of the wind and sunlight, a mist net is nearly undetectable. It's like a big, non-sticky, nylon spider web.
Interestingly, some spiders put visible lines in their webs so that birds will see the strands and and not wreck a hard morning's work. Much like a badly placed spider web, Nestwatch can require a bit of ingenuity when confronted with the job of net concealment in backyards that lack dense vegetation. There are some things we can do to make the net harder to see. For example, we try to go out on calm days to keep the net from swaying in the wind. Also, we make sure to pick leaves and branches out of the net before we start catching birds.
Mist nets are made up of a series of pockets. The line you see in this photo above Lynn's arm is the top of one of the pockets. Taking birds out of a mist net is a little tricky. There's some technique involved. Without going into too much detail, you have to get the feet out first and then the head.