Variation in vocal response of Plumed Frogmouth (Podargus ocellatus plumiferus) to call-playback Geoffrey C. Smith A,C and Benjamin J. Hamley B A Biodiversity and Ecosystem Sciences Unit, Queensland Department of Environment and Resource Management, 80 Meiers Road, Indooroopilly, Qld 4068, Australia. B Present address: 15 Bayford St, Oxley, Qld 4075, Australia. C Corresponding author. Email: geoff.smith@derm.qld.gov.au Abstract. A call-playback study of the southern subspecies of Marbled Frogmouth (Podargus ocellatus plumiferus), the Plumed Frogmouth, was undertaken over three years in the Conondale Ranges of south-eastern Queensland to examine seasonal patterns in behavioural response. Responses to call-playback were similar across years, but with some variation that could have been explained by rainfall or habituation. There was a short peak in response in August (owing to territorial behaviour associated with the onset of breeding), a lull in September (associated with laying and incubation), a peak from November to March (coinciding with broading, nestling development, fledging and dispersal) and then a lull during the cooler months of April to July (the non-breeding season). Monitoring for Plumed Frogmouth is probably best undertaken from November to March to maximise the likelihood of detecting the species. Introduction The southern subspecies of the Marbled Frogmouth (Podargus ocellatus plumiferus) – the Plumed Frogmouth – is a shy and cryptic territorial nocturnal species that inhabits the canopy of well-developed subtropical vine forests of south-eastern Queensland and north-eastern New South Wales. It was considered by Hollands (1991) to be one of the hardest of the night birds of Australia to study. Owing to its secretive behaviour, there were few records of Plumed Frogmouth before the 1980s, and some sightings are likely to be inaccurate owing to misidentification of the related Tawny Frogmouth (P. strigoides) (Corben and Roberts 1993). In 1976 Plumed Frogmouths and their calls were noted for the first time in the Conondale Ranges of south-eastern Queensland (Roberts and Ingram 1978). The subsequent electronic recording of calls and the use of recordings in call-playback has provided a useful method for detecting the species and has led to an increase in the known distribution of the species and the discovery of a significant population of Plumed Frogmouth in the Conondale Ranges (Corben and Roberts 1993). Smith et al. (1994, 1998) also had moderate success in capturing individuals using call- playback to lure birds into mist-nets. Ecological assessments suggest that the habitat of Plumed Frogmouths has been lost or degraded through land clearing and timber harvesting and that it continues to be threatened by local fire regimes (Smith et al. 1998; Garnett and Crowley 2000). It is possible that Plumed Frogmouths may be at further risk from degradation of its habitat as a result of predicted climate change from global warming (Dunlop and Brown 2008). Because vocalisations make birds more ‘detectable’, the use of playback of avian calls to initiate vocal responses to reveal the presence of species, or to estimate their numbers, is now used widely to assist conservation studies and wildlife management (Gilbert et al. 2002; Puglisi and Adamo 2004). We examined the variation in response to call-playback shown by Plumed Frogmouth in order to investigate: (1) annual pattern in calling behaviour in relation to life-history events, primarily breeding versus non-breeding; (2) consistency in vocal behaviour between years; and (3) opportunities for maximising response to call-playback. Study area and methods The study was conducted over three years, from 1993 to 1996, in the Conondale Ranges, north-north-west of Brisbane, in south- eastern Queensland. The southern end of the Conondale Ranges lie north of the Brisbane Valley (which divides these ranges from the d’Aguilar Range to the south) and extend north to include the Bellthorpe Range and the Brooloo Ranges. Plumed Frogmouths occupy rainforest and wet sclerophyll habitat along drainage lines. The vegetation used by Plumed Frogmouths has been described by Smith et al. (1998). Rainfall records were compiled from the nearby Imbil Forest Station in the northern part of the Conondale Ranges to investigate the potential for a relationship between moisture levels, accessibility of food and breeding. Mean annual rainfall was 1166.6 mm. Annual rainfall totals were 1594 mm (1992), 869 mm (1993), 814 mm (1994) and 1030.2 mm (1995). The typical pattern of rainfall consists of a dry quarter coinciding with winter, with most rainfall occurring from mid- to late summer. Normal rainfall in February of 1992 and 1995 led to the higher annual totals than the drier years of 1993 and 1994. In 1994, conditions in the Conondale Ranges were very dry and wildfire was recorded in wet forests on the western side of the range (G. C. Smith and B. J. Hamley, pers. obs.). CSIRO PUBLISHING Short Communication www.publish.csiro.au/journals/emu Emu, 2009, 109, 339–343 Ó Royal Australasian Ornithologists Union 2009 10.1071/MU09064 0158-4197/09/040339