Mound Characteristics and Behaviour of the Orange-footed Scrubfowl in the Seasonal Tropics of Australia

Abstract

Seventeen site characteristics associated with the location of incubation mounds of the Orange-footed Scrubfowl Megapodius reinwardt were measured for three habitat types: monsoon forest, regeneration forest and a sandy coastal vine thicket adjacent to an intertidal zone. The three habitats differed with respect to shrub cover, litter cover, canopy cover and several tree measurements. Mound sites differed from random sites with respect to several variables, and these differences can be attributed to the litter-collecting activities of the birds, which disrupt the vegetation on and near the mounds. Internal mound temperatures were recorded over a 12 month period in 10 active mounds, two disused mounds and at two control sites. Active mound temperatures in all three habitats were similar despite significant mound site differences, particularly with respect to canopy cover and incident solar radiation. Whereas the decomposition of litter was the primary source of heat for the mounds in the monsoon and regeneration forests, both solar radiation and microbial decomposition contributed to the heat of the mounds in the sandy coastal vine thicket. Soil temperatures in disused mounds and at control sites decreased with the onset of monsoonal rains, but active mound temperatures remained stable during this period. Behavioural observations were recorded over a 19-week period for a pair of Orange-footed Scrubfowl at an active mound. The collection and incorporation of leaf litter into the mound increased significantly as monsoonal rains intensified. The birds were most active during the early morning period. Hatchlings and juvenile birds were observed in the study area throughout the eight months of field work and one colour banded bird was observed defending two mounds on several occassions.