An estimate of the Plumed Frogmouth Podargus ocellatus plumiferus population size in the Conondale Ranges

Abstract

Marbled Frogmouths are rare, cryptic, shy, nocturnal birds restricted primarily to rainforest and wet sclerophyll forest. Two sub-species are recognized in two isolated areas on the east Australian coast. A stronghold for the southern subspecies (Plumed Frogmouth) occurs in the Conondale Ranges. This area has been subject to forestry practices for the past 100 years. Because of public concerns and a perceived need to undertake planning and management to assist in conserving the species, a study was undertaken to assess its population status. Radio-tracked adults associated primarily with rainforest and wet sclerophyll along drainage lines, although gullies containing rainforest species within dry sclerophyll were also utilized. Taped playback of Plumed Frogmouth calls revealed a distribution within core habitat (rainforest and wet sclerophyll) across the Conondale Ranges. Individuals radio-tracked in the Conoodale Ranges occupied home ranges from 5 to 18 ha. Estimates of the combined home ranges of pairs ranged from 12 to 19 ha. Home range overlap between pairs was minimal. An assessment of the area of currently suitable core habitat (14 508 ha) within the Conondale Range forested area suggests that conservatively, 755 pairs currently exist; if potential future habitat (i.e., regenerating) of 1 954 ha is taken into consideration, this figure will rise to 857 pairs. If use of dry sclerophyll by birds is also taken into account then these estimates may be as high as 858 and 974 pairs respectively. There is currently no reliable estimate of the amount of suitable habitat, which is not occupied by Plumed Frogmouths or of habitat only occupied by single unpaired birds or non-breeding pairs. Future research should aim to redress this lack of information which could severely reduce any estimates of the numbers of breeding pairs.