Hummingbird bands

A band to go on a hummingbird’s leg is unimaginably small.  A 10.2 cm by 15.2 cm aluminum sheet like the one below is enough to make 300 bands, and the biologist has to cut each one out individually, form it and file it smooth.  A job for a watchmaker!

Females have bigger legs than males, so the bands have to be cut differently.