The clutch is typically two eggs. The eggs are unmarked (but may become stained by debris in the nest), whitish, pale blue, green, or pink, and have a coating that resembles lime. Egg weight ranges from 3.3 to 8.0% of the female's weight. Incubation lasts 42 to 55 days, depending on the species. Both sexes incubate; like their relatives, they do not have brood patches, but their feet become vascularized and hot, and the birds place the eggs under the webs. Eggs lost during the first half of incubation are replaced.