Most megapode species rake organic material into mounds in which they incubate
their eggs. To test predictions of a model proposed for temperature regulation
in incubation mounds (the ‘Seymour Model’), I collected data on
the physical characteristics of these mounds of the sympatric wattled
brush-turkey (Aepypodius arfakianus), brown-collared
talegalla (Talegalla jobiensis) and New Guinea megapode
(Megapodius decollatus) in Papua New Guinea. Data from
mounds supported several predictions of the Seymour Model: (1) there is a
critical mass needed for mounds to heat to incubation temperatures, (2) mounds
are stable homeotherms, (3) mounds cool after they are abandoned, and (4)
mounds with different proportions of organic material differ in size. Data did
not support predictions that (1) mound size will change with changes in
ambient air temperature, and (2) mounds in high-rainfall areas will be convex
to shed water. Mounds of New Guinea megapodes and brown-collared talegallas
were similar and differed from those of wattled brush-turkeys in size,
composition, temperature profile and location of eggs. These differences were
consistent with the Seymour Model. The Seymour Model is robust enough to
explain differences in mounds of sympatric megapodes, which differ in their
taxonomy, behaviour and ecology.