Orientation of tawny frogmouth (Podargus strigoides) nests and their position on branches optimises thermoregulation and cryptic concealment

Abstract

Tawny frogmouth (Podargus strigoides) nests were surveyed in grassy woodland, dry sclerophyll forest and suburbia in the Australian Capital Territory. In total, 253 tawny frogmouth nests were recorded in 145 nest sites. Nests were oriented to the north-east, which would expose them to morning sunshine and partially shelter them from the prevailing wind. Most nests were placed in rough or flaky-barked tree species, on open mid-branch sites with no foliage, where the birds’ plumage and posture resemble the colour and form of the branches. Although smooth-barked gum trees were the most abundant types in the dry sclerophyll forest they were seldom used. Nest sites in all habitats were similar; the mean nest height was 9.2 m, and most nests were set on forks in the lowest branches. By placing their nests in these positions tawny frogmouths likely maximise their potential thermoregulation, protection from wind, concealment from predators, and detection of approaching predators.