All Papuan bowerbirds lay one egg, while Australian species lay one to three with laying intervals of two days. Bowerbird eggs are around twice the weight of those of most passerines of similar size – for instance eggs of the satin bowerbird weigh around as against a calculated for a passerine weighing . Eggs hatch after 19 to 24 days, depending on the species and are a plain cream color for catbirds and the tooth-billed bowerbird, but in other species possess brownish wavy lines similar to eggs of Australo-Papuan babblers. In accordance with their lengthy incubation periods, bowerbirds that lay more than one egg have asynchronous hatching, but siblicide has never been observed.