147 AUSTRALIAN FIELD ORNITHOLOGY 2005. 22, !47- 15! Notes on the Behaviour of the Rufous Dasyomis broadbenti

JOHN M. PETER , 415 Riversdale Road, East Hawthorn, 3123 (Email: [email protected])

Summary Most behavioural aspects of the Rufous Bristlebird Dasyornis broadbenti, apart from its song, are poorly known. As a result of opportunistic observations between 1998 and 2000 near Aireys Inlet and Anglesea, Victoria, three different types of behaviour (courtship feeding, interspecific relations and amplification of song) of the vulnerable subspecies D. b. cwyochrous of southern Victoria are described.

Introduction The Rufous Bristlebird Dasyomis broadbenti is claimed to be the best known of the three species of (Serventy 1982), but in fact there has been very little published on the behaviour of the species (Higgins & Peter 2002). This is presumably because of the habits of Bristlebirds: many early observers remarked that the birds were often heard but seldom seen, as their presence is usually announced by their strident calls (Belcher 1903, 1914; Hill 1903). Bristlebirds are often considered shy (Hill 1903; Campbell 1907; Purnell 1915; White 1918) and, for many observers, their only sighting of the species is of a , having been startled in the open, scuttling into the nearest undergrowth (e.g. Anon. 1996). Their habit of hiding in dense cover makes observation of any behaviour difficult although, when hidden in such cover, individuals can occasionally be quite confiding. The function of many displays of the Bristlebird is unknown, although most have been assumed to be related to courtship (White 1918; Sutton 1927; Lang 1946). Published observations of the displays and other behaviour of the Bristlebird have involved both extant subspecies. There is, however, little indication of whether the behaviour of the subspecies D. b. caryochrous (restricted to the Otway Range and its coastal periphery in southern Victoria) is similar to that of the nominate subspecies D.b. broadbenti (restricted to coastal areas of western Victoria and south-eastern ); certainly their calls differ (Rogers 2003; JMP pers. obs. ). A greater knowledge of the behavioural ecology of the Bristlebird may have wider implications for the conservation of the species.

Courtship feeding Courtship feeding by Bristlebirds has been observed previously (e.g. McCall 1987; Hewish 2002; Higgins & Peter 2002), but has not been described in any detaiL The function of courtship feeding is to reinforce or maintain the pair-bond, and it generally involves the male feeding the female. It usually takes place early in the breeding season, often associated with copulation or egg-laying, though occasionally continues into the period of incubation and brooding (Campbell & Lack 1985). AUSTRALIAN 148 PETER FIELD ORNITHOLOGY

In early August 1998, presumably at or near the beginning of the breeding season, I observed two Bristlebirds in the open, walking slowly, one after the other, along the edge of an extensive strip of coastal clifftop scrub at Aireys Inlet, Victoria (38°27'S, 144°06'E). (For a detailed description of the vegetation at this site, see Wilson et al. 2001.) As they walked, each bird often picked at the surface of the layer of leaf-litter, and occasionally stopped to probe the litter more deeply. Throughout the observation, which lasted for several minutes, they remained in visual contact with each other (as they were both in the open), and were never more than 3 m apart; no contact calls were heard. After a minute or two, the leading bird stretched up to pick an object from a developing inflorescence of a Coastal Wattle Acacia longifolia var. sophorae. It was impossible to identify the tiny item that the bird had gleaned, but it is likely to have been either part of the flower or possibly a small on the flower. The bird then quickly dashed back to the second bird, and passed the item directly into its bill (i.e. bill-to-bill transfer). The second bird did not solicit this offering, either by begging in the manner of a young bird or by adopting a submissive posture, nor was an eliciting call heard. Whatever the item, it appeared to offer little nutritive value, being so small. After this encounter, both birds resumed foraging silently. This observation was briefly summarised by Higgins & Peter (2002). Another observation of courtship feeding, near Apollo Bay, Vic. (McCall1987), described an instance where a male Bristlebird 'selected and then proffered a morsel of oats' from a feeding tray, and a female accepted or 'selected' this offering of food. Though the manner of feeding was not clearly described, it was at least inferred that the food was not transferred from bill to bill, but was possibly deposited, perhaps on the ground, in front of the female, where it could be 'selected' by her. Immediately after the encounter, the male flew to a nearby perch and chattered excitedly (McCall 1987). Both extant subspecies of the Bristlebird (nominate broadbenti and caryochrous) have been recorded courtship feeding (Higgins & Peter 2002). Some of those observations have occurred at artificial feeding sites (McCall 1987; Higgins & Peter 2002), where it is possible that a relative abundance of food may have encouraged this behaviour. Nevertheless, Bristlebirds have been recorded courtship feeding well into the breeding season, including when incubating and brooding, with the female being called from the nest to be fed (Campbelll907; Chapman 1999; Higgins & Peter 2002; P.N. Reilly, Birds Australia Nest Record Scheme).

Interactions with other species Interactions between different species can occur in various forms. For some species, where calls are a major tool in communication (especially for those species which inhabit dense where visual cues are of limited value), interactions may take place with some distance between individuals. Other interactions, of a more physical nature, occur at much closer proximity. There are few published records of Bristlebirds being involved in interspecific exchanges, but both types of interaction have been observed. One record, near Robe, in south-eastern South Australia, described a Rufous Bristlebird calling from within a thicket, with each call being answered by a Stubble Quail Cotumix pectoralis in a nearby crop, about 45 m away (Sutton 1927). It was suggested that the second part of the song of the Bristlebird was sufficiently similar to the three-note call of the Quail (see Marchant & Higgins 1993 for details) to elicit a response. There is also a published record of a face-to-face interaction with a Superb Fairy-wren Malurus cyaneus at an artificial feeding site near Apollo VOL. 22 (3) SEPTEMBER 2005 Rufous Bristlebird Behaviour 149

Bay. In a confrontation between a male Bristlebird and an apparently aggressive ('much puffed-up') brown-plumaged Fairy-wren, in a dispute over food, the Bristlebird reacted submissively. Despite being much larger than the aggressor, the Bristlebird did not defend itself other than to vacate the feeding-tray (McCall 1987). There are also unpublished observations in the Birds Australia Nest Record Scheme of aggressive behaviour by Bristlebirds near their nests: one bird was recorded chasing a male Common Blackbird Turdus merula (P.N. Reilly); and two birds attacked a Common Blue-tongued Lizard Tiliqua scincoides near their nest, pecking its back and standing in front of the lizard with wings spread until it left the area (L. Richardson). At the Aireys Inlet clifftop (the same site as already mentioned), I watched a Bristlebird bathing in a shallow, muddy puddle in a wheel-rut. It stood in belly­ deep water, repeatedly dipping its head under water and flapping and fluttering its wings, in a manner described for many species of birds. As it bathed, an adult Crimson Rosella Platycercus elegans stood at the edge of the puddle, occasionally leaning forward to drink. Though the birds stood less than a metre apart, they displayed no aggression towards each other. However, when a female Blackbird emerged from the dense scrub some distance away, she immediately fl ew low towards the bathing Bristlebird. Landing about 3 m away, the Blackbird aggressively charged the Bristlebird, hopping rapidly while giving a shrill high-pitched whistle (Aggressive seee call described by Cramp 1988). When confronted with this challenge, the Bristlebird quickly retreated, running (not flying or fluttering) towards the nearest cover, but stopped short, and remained in the open. The Blackbird briefly gave chase, but stopped when it reached the puddle, effectively displacing the Bristlebird, then stood momentarily before flying away. After the Blackbird had gone, the Bristlebird returned to the puddle, bathed briefly (and watchfully), and then moved silently into a nearby thicket, where it was lost from view. It was not heard calling in the few minutes after the incident. Throughout the whole episode the Rosella remained standing beside the puddle, and was not affected by the Blackbird, nor did the Blackbird pay it any attention. This observation was briefly summarised by Higgins & Peter (2002). This aggressive encounter raises the issue of possible competition between species that occupy rather similar ecological niches. Both Bristlebirds and Blackbirds feed largely on the ground, taking and berries (Cramp 1988; Higgins & Peter 2002). If Blackbirds are aggressive to the more submissive Bristlebirds, is it possible that competition between the two species over food resources could adversely affect the survival of the threatened Bristlebird? Blackbirds are widespread in the coastal fringe, and the two species co-exist in many areas (Emison et al. 1987; Horton 2000), but any competition between them is likely to be most intense at sites where Blackbirds occur at high densities. Such sites are typically away from large, unbroken tracts of scrub, and more likely where the scrub is fragmented or marginal, such as around coastal towns, where gardens abut areas of coastal scrub (e.g. at Aireys Inlet and Fairhaven, Vic.: Reilly 1991, 2003), or where revegetation has allowed coastal scrub to become established around the edges of built-up areas (e.g. at Jan Juc, Vic.: Peter 2003). Around the eastern extremity of the range of the Rufous Bristlebird, between Bells Beach and Jan Juc, extensive revegetation of the clifftop with local indigenous plants since 1987 has allowed the species to extend its range eastward by several kilometres since the mid 1990s (Peter 2003). This revegetation has meant that there is now an indistinct interface between gardens and areas of recently established coastal scrub. Blackbirds are common inhabitants of the local gardens, and are also common in adjacent areas of scrub. Judging from the number of calling Bristlebirds, AUSTRALIAN 150 PETER FIELD ORNITHOLOGY they also occur at quite high densities in the area (Hewish 2003; JMP pers. obs.). Thus it would appear that both species co-exist, in this case, in good numbers. Furthermore, the local population of Bristlebirds has been able to extend its range in the area to include sites that were formerly the domain of Blackbirds. These limited data suggest that competition for food resources is probably not a limiting factor, but it raises the need for ongoing research, monitoring the population dynamics, breeding success and dispersal of Bristlebirds and Blackbirds in southern Victoria.

Possible directional amplification of song On 8 August 2000, while walking along the beach between Urquharts Bluff and Anglesea, Vic., my attention was attracted by an unusual song of the Bristlebird. Though the song consisted of the usual components (an initial series of undulating pairs of notes quickly followed by a whip-like crack), it sounded somewhat distorted. On investigating the call, I fo und a Bristlebird singing vigorously while standing in a culvert (for the drainage of an ephemeral creek) that ran beneath the Great Ocean Road, connecting the heathland on one side with the beach on the other. The song reverberated through this pipe, and, when the bird was standing in front of the pipe, my perception was that its song was much louder than calls made in less confined spaces. Calls made in the open are dissipated, and those made from among dense vegetation distorted, but by using the culvert to amplify the call, the sound-waves were concentrated directionally, presumably resulting in the sound travelling further. No other Bristlebirds were heard singing in response to the enhanced calls, however. It is unknown whether this site was deliberately chosen by the Bristlebird for its acoustic properties, whether the bird regularly sang from this position, or if it was coincidental. A few ground-dwelling species are known to regularly use the topography of their surroundings to amplify their calls. Probably the most sophisticated is the Kakapo Strigops habroptilus of New Zealand. It excavates a series of depressions or bowls on ridge-tops above the bush-line, utilising sites with good acoustics, such as at the base of overhanging rocks or rock-faces which act as sound-reflectors and enable its booming calls to be projected for up to 5 km (Higgins 1999). Similarly, the Superb Lyrebird Menura novaehollandiae often builds its display mounds on ridges or slopes, rather than in densely vegetated gullies, which enables its song to be audible over greater distances (Higgins et al. 2001). Furthermore, it has been suggested that many songbirds sing in early morning because their songs travel further at that time, with the sound-waves reflected and refracted along the boundary between layers of cool and warm air that occur at sunrise (McFarland 1981; Burton 1985; Attenborough 1998). Whether Bristlebirds employ similar strategies to enhance their songs requires further corroborating evidence. Another aspect of this Great Ocean Road observation was the apparent willingness of the Bristlebird to enter the culvert. Culverts might be considered as a means to encourage Bristlebirds to travel between the heathland on one side of the road and the beach on the other without the risk of being struck by passing traffic (Bristlebirds have been recorded as road-kill; Higgins & Peter 2002). This type of facility has been used to good effect in the alpine regions, where tunnels have been built beneath busy roads to allow the natural dispersal of threatened species such as the Mountain Pygmy-possum Bwramys parvus and the Corroboree Frog Pseudophryne corroboree (Mansergh & Scotts 1989). Overall, these observations contribute to the range of behaviours recorded VOL. 22 (3) SEPTEMBER 2005 Rufous Bristlebird Behaviour 151 for the Rufous Bristlebird. In the wider context, some may provide an insight into research that is required to ensure the conservation of this threatened species.

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Received 23 September 2004 •