VOL. 17 (5) MARCH 1998 245 AUSTRALIAN BIRD WATCHER 1998, 17, 245-253 The Eastern Bristlebird Dasyomis brachypterus in East Gippsland, Victoria by ROHAN CLARKE1 and MICK BRAMWELL, Department of Natural Resources and Environment, Gippsland Area, 7 Service Street, Bairnsdale, Victoria 3875 1Current address: 4 Reilly Court, South Croydon, Victoria 3136 Summary All sites in East Gippsland, Victoria, where the Eastern Bristlebird Dasyomis brachypterus has been recorded were surveyed between 1990 and 1995. The species has apparently disappeared from all known Victorian locations except Howe Flat in far East Gippsland, an area of reserved natural vegetation that is contiguous with a similar area in south-eastern New South Wales where the species also occurs. At the historical sites, the species appeared to occur in mosaic ecotonal habitats, with Riparian Scrub the most common vegetation type occupied by Bristlebirds. Inappropriate fire regimes may be responsible for the species' apparent decline in Victoria. At least 80% of the 10 historical sites have been burnt between the mid 1960s and 1995, and 50% of these have experienced large­ scale and/or frequently successive fires. In contrast, Howe Flat has experienced only small-scale, low-intensity fires during the same period, resulting in a mosaic of vegetation age classes. Introduction Considerable cause for concern exists with regard to the long-term survival of the Eastern Bristlebird Dasyomis brachypterus. The species' conservation status in Victoria has recently been changed from Vulnerable to Endangered (CNR 1995) and it is listed under that state's Flora and Fauna Guarantee Act 1988. It is listed as Vulnerable in New South Wales (Schedule 2 of the Threatened Species Conservation Act 1995) and is considered Endangered in Queensland (Garnett 1992a). Nationally, it is considered Vulnerable and listed under the Endangered Species Protection Act 1992. Historical records show that the Eastern Bristlebird was distributed in discrete pockets from the Conondale Range, south-eastern Queensland, along the coast and adjacent ranges to Marlo in eastern Victoria (Blakers et al. 1984, Garnett 1992a). Throughout this range the number of localities from which the species has been recorded has declined substantially m recent years (Holmes 1989, Baker 1996a). There is convincing evidence that populations in Queensland and northern New South Wales (referred to as the northern population) have declined. Holmes (1989) detected Bristlebirds at only 13 of 23 previously known localities and concluded that only a few hundred birds survive. Of the 103 territories that Holmes (1989) recorded, 88 were resurveyed by Lamb et al. (1993), who found only 36% occupied, although they found seven new territories, giving a survival rate of 44% from 1988 to 1993. Severe drought followed by a wildfire in 1991 has significantly reduced the largest northern population at Spicers Gap and the total northern population is currently likely to be less than 100 individuals at two isolated localities (Lamb et al. 1993, Baker 1996a). Similar declines have also been noted in New South Wales, where Baker (1996a) recorded at least nine localities where Eastern Bristlebirds are now presumably extinct and two localities with a negligible number near Wollongong. He estimated that the two substantial populations near Wollongong (referred to as the central population) numbered approximately 1300 individuals and were 'unlikely to total as many as 2000' as suggested by Garnett (1992b). A recent survey of suitable habitat in the Nadgee Nature Reserve (along with the adjacent Victorian population, referred to as the AUSTRALIAN 246 CLARKE & BRAMWELL BIRD WATCHER southern population) detected 26 Eastern Bristlebirds (Baker 1996b), at a lower density than published for the Barren Grounds Nature Reserve (Baker 1996a). In Victoria, Eastern Bristlebirds have been recorded from dense vegetation near the coast from Marlo to the New South Wales border, with unconfirmed records from South Gippsland (Emison et al. 1987, Mitchell1995). In East Gippsland, ten precise (100m X 100m resol,lltion) localities are known, with all records occurring before 1990. Occurrence of Eastern Bristlebirds at these sites is currently unknown but if the same population trends are occurring in Victoria as interstate, the species would be at great risk. The shy and cryptic nature of the Eastern Bristlebird, together with its similarity in call, appearance, behaviour and habitat preference to those of the Pilotbird Pycnoptilusjloccosus, may have led to the species being overlooked in Victoria and to possibly erroneous identification and reporting. One effective method to ascertain the presence of the species in an area is to use playback of the species' call to elicit a response. Holmes (1989) used this technique for censusing northern populations. However, limitations occur in the use of call playback. If over-used in an area, it may have detrimental effects on Bristlebirds, as they are particularly sensitive to disturbance and readily abandon their nests (McNamara 1946, Chaffer 1954, Holmes 1989). In New South Wales and Queensland, Eastern Bristlebird populations are distributed predominantly near the boundaries between vegetation communities. The northern population inhabits open forest adjacent to rainforest areas (Holmes 1989), whereas central and southern populations mainly occur in heath or Melaleuca thickets adjacent to woodland areas ( Recher 1981 , Bramwell et al. 1992 ) . Specific structural vegetation characteristics, such as thick ground cover with either tall shrub or low tree cover, also appear important for central populations (Baker 1992). In Victoria, information on vegetation community and habitat preference for Eastern Bristlebirds is scant, with no summary of existing information. The main threat to the Eastern Bristlebird appears to be inappropriate fire regimes (Garnett 1992a), and the population density of Eastern Bristlebirds is apparently influenced by the time since the last fire (Blakers et al. 1984, Holmes 1989, Bramwell et al. 1992, Pyke et al. 1995). The size of the area burnt and the proportion of that area burnt may also be important (see Lamb et al. 1993). The Eastern Bristlebird may be unable to find refuge in large-scale fires because of its relative immobility. Its apparently limited ability to disperse may mean that it is unable to recolonise areas of suitable habitat, with remnant populations thus remaining isolated from one another. Its survival is further compounded by a low reproductive rate: there are usually only two eggs per clutch and often only one young is fledged (Chaffer 1954, Holmes 1989). In Victoria no summary of fire history at Eastern Bristlebird localities has been recorded. The objectives of the surveys described in this paper were to: (1) Use the call-playback technique to sample all localities where the Eastern Bristlebird has been recorded in East Gippsland to determine if it is still present; (2) Use this technique to sample areas of habitat similar to those in (1) in East Gippsland to determine presence of the species, and (3) Record vegetation communities and available fire-history information at all precise record localities of the Eastern Bristlebird in East Gippsland. Methods Surveys for Eastern Bristlebirds were performed at sites where the bird had previously been recorded and at potential habitat sites in coastal and lowland areas in East Gippsland between Toorloo Ann, VOL. 17 (5) MARCH 1998 Eastern Bristlebird in Victoria 247 Table 1. Details of surveys at localities where Eastern Bristlebirds have previously been recorded in East Gippsland. See Figure 1 for location of survey sites 1-10. Source: Victorian Wildlife Atlas 1995. Location and map No. of Date of When surveyed Results number records record 1. Toorloo Arm 2 Jan. 87, Jan. 88 Feb. 95 No response 2. Second Island 1 Jan. 87 Mar. 91 , undated No response 3. Point Ricardo 1 Aug. 78 Jan. 95 No response 4. Cape Conran 2 Aug. 77, Aug. 78 Oct. 90, Jan. 95 No response 5. East Y eerung River 1 Mar. 80 Jan. 95 No response 6. West Bemm River 2 Feb. 83 Nov. 90 (twice) , No response Jan. 95 7. Bellbird Creek Apr. 90 Nov. 90, Jan. 95 No response 8. Clinton Rocks Dec. 79 Feb. 95 No response 9. Red River Oct. 80 Dec. 91 , Feb. 92 , No response Nov. 95 10. Howe Flat Sept. 85 Mar. 94 Five heard, one seen near Lake Tyers, and Howe Flat, east of Mallacoota, between 1990 and 1995 (Table 1, Figure 1). Surveys were carried out between 1990 and 1995 (see Table 1). The area from Marlo to Bemm River was surveyed between October 1990 and March 1991 and again in January 1995. Sites south of Cann River were surveyed between December 1991 and February 1992 with additional surveys in November 1995. The site east of Mallacoota (Howe Flat) was surveyed in March 1994. At each location, sites were surveyed by playing a variety of calls at points approximately 50 m apart in an attempt to elicit a response. On each occasion recordings were played for several minutes followed by a short listening period. Where possible, existing networks of tracks were used. However, sites without tracks were surveyed by walking throughout a search area. A pilot study indicated that the playback call could be heard easily at a distance of 100m, as could any calling Bristlebirds (see Bramwell et al. 1992). This distance was used in determining the total survey areas for each location. Tracks and the area covered at each location were mapped at 1:25 000 or 1:50 000 and the total area surveyed was determined. At each site this area ranged from 3.5 to 70 ha. All surveys were conducted between 0700 and 1300 h Eastern Summer Time; most were concluded before 1000 hand lasted between 60 and 120 minutes. Only on cooler days when activity and vocalisation of other passerines remained high did surveys continue past 1000 h. For survey work completed in 1990 and 1991 calls used in the playback originated from the Barren Grounds Nature Reserve, whereas surveys completed in 1995 used calls from Howe Flat birds.