The Relationship between Body Weight, Egg Weight, Incubation Period, Nestling Period and Nest Site in the Psittaciformes, Falconiformes, Strigiformes and Columbiformes.

The theory that landbirds which nest in holes tend to have larger clutches, longer incubation periods and longer nestling periods than those which nest in the open was tested by comparing the Psittaciformes, Columbiformes, Falconiformes and Strigiformes. It was found that among the graminivore-frugivores, the hole-nesting Psittaciformes produce larger clutches, have longer incubation and nestling periods than the open-nesting Columbiformes. Among the carnivore-insectivores, the Strigiformes (which predominantly nest in holes) produce larger clutches and have longer nestling periods than the open-nesting Falconiformes but there is no difference in incubation periods.