Barbara Wilson

Relationships between site factors and distribution of Phytophthora cinnamomi in the Eastern Otway Ranges, Victoria.

The Eastern Otway Ranges, Victoria is an area recognised for its significant flora and fauna communities. An area of about 7000 ha, the Anglesea heathlands has been listed on the register of the National Estate. Although symptoms of the plant pathogen Phytophthora cinnamomi have been recorded in the area since the 1970s, the extent of infestation and its effects have not been documented. The aims of this study were to assess the distribution of infestation, identify the relationship of plant infection to site variables and to identify evidence of spread of the pathogen. The presence of P. cinnamomi was assessed at 50 study sites by a visual evaluation of the vegetation, using species such as Xanthorrhoea australis (Austral grass tree) and Isopogon ceratophyllus (horny cone bush) as indicator species. Soil and plant tissues were assayed for the presence of the pathogen by cotyledon baiting and immunoassay methods. Phytophthora cinnamomi was isolated at 76% of the study sites from the floristic communities identified: heathy open forest; heathy woodland I and II; Bald Hills heathland; riparian open forest. There were significantly more diseased sites at lower altitudes. The pathogen is widely spread and causing disease throughout the area, but at present often only in small patches. There is an urgent need for disease management to protect the significant communities. These findings suggest that management actions such as mapping current infestations, closing tracks and implementing vehicle wash-down points are required.

Detection and habitat use of the Rufous Bristlebird (Dasyornis broadbenti) in coastal heathland, in south-western Victoria, Australia

Abstract The Rufous Bristlebird (Dasyornis broadbenti) is a sedentary, ground-dwelling passerine of southern Australia, which is listed as nationally vulnerable, and as near-threatened (lower risk) in Victoria. The species inhabits a variety of vegetation, including shrub thickets in coastal gullies to heathlands on limestone cliffs. This study aimed to assess the size, distribution and habitat use of a population of the subspecies D. b. broadbenti at Portland in south-western Victoria. Monthly surveys (2002–03) were conducted on foot for 1 h after official sunrise and 1 h before official sunset, and presence of Bristlebirds recorded using vocalisations and sightings. Observations outside of the survey times were also recorded to estimate the size of territories and core area of occupancy. To quantify habitat preferences, vegetation composition and structure were measured in areas where Bristlebirds were present, as well as surrounding areas where they were not detected. The population in the survey areas was estimated at between 70 and 86 individuals in the 170-ha survey area. The estimated size of territories of eight selected pairs of Bristlebirds ranged from 0.5 to 3 ha, with core areas of occupancy ranging from 0.2 to 0.6 ha. During the nesting season (August-November) Bristlebirds were detected at greater frequencies in the core area of occupancy within each territory. Significant associations were found between the presence of Bristlebirds and floristic associations dominated by the native environmental weeds Acacia sophorae and Leptospermum laevigatum. Bristlebird presence was significantly positively correlated with increasing vegetation density in the mid-canopy level (80–120 cm) indicating that vegetation structure is a key factor in habitat use.

The distribution and ecology of the Rufous Bristlebird (Dasyornis broadbenti) at Aireys Inlet, Victoria

Abstract A study to assess distribution, numbers and habitat of the Rufous Bristlebird was conducted during 1997 and 1998 along the coast at Aireys Inlet, Victoria. Monthly surveys were conducted along selected pathways for 1 h at sunrise, noon and late afternoon. Birds were recorded on the basis of sightings and calls; 75% of records were from calls. The number of records of birds for April—June was significantly lower than for January—March, July—September and October—December. There was no difference in frequency of records due to weather conditions (clear, overcast or rain), presence of wind or difference in temperature. The Rufous Bristlebird inhabited remnant coastal vegetation, but also utilised nearby house gardens and road verges. Birds appeared to occupy distinct territories, with each separate territory occuring along a narrow strip of land on the coastal cliffs. The number of territories identified ranged from 14 to 33. Territories were occupied predominantly by pairs of birds. The minimum number of birds present was estimated for each survey session and ranged from 2 to 34. A conservative estimate of the bristlebird population in the area, based on the assumption that a territory was occupied by a pair, was thus between 28 and 66. A number of threats to the Rufous Bristlebird were identified in the study area including loss and fragmentation of habitat from housing developments and walking tracks. Introduced predators including foxes, cats and rats have been recorded, but their impact is unknown. The effect of people walking along the tracks and the presence of dogs is unclear.