Builders and Cannibals

Male bowerbirds skip muscles and color and compete on craft instead. Each builds a bower, a little stage woven from twigs and laid out with collected treasures sorted by color. A female tours several before deciding. What she is really judging is the mind behind the work: patience, planning, and an eye for arrangement.

For some males, courtship ends in death. A female praying mantis may bite the head off her partner mid-mating, and a male redback spider somersaults straight onto the female's fangs. It sounds suicidal, but the math works: a male who is eaten often fertilizes more eggs and fathers more young than one who survives the encounter.