2.2 Field methods
During the incubation period, we captured and measured the body size
(body mass and tarsus length) of breeding males and females using
standard protocols . To observe the parents’ incubation behavior, we set
up a nest camera (Bushnell 119776C) anchored to the ground and
positioned 1.5 m away from the nest. The camera recorded for 72 hours at
one-minute intervals. In total, we captured and measured the body size
and ornament traits of 131 male and 145 female adults. We were able to
obtain data from 111 nests in which both parents were captured.