Peoples Bay Research Articles

Conservation of the Noisy Scrub-bird: a review of 35 years of research and management

The Noisy Scrub-bird is a small, semi-flightless insectivore which forages in leaf litter and the lower stratum of dense vegetation. More widespread when discovered last century the species declined rapidly after European settlement of Westem Australia due to habitat clearing and large scale, uncontrolled wildfires. A small, remnant population survived in dense low forest and thickets on Mt Gardner at Two Peoples Bay. Exclusion of fire from scrub-bird habitat allowed the population at Two Peoples Bay to increase through natural breeding. Translocations to new sites, where successful, have provided more habitat for the scrub-bird resulting in seven sub-populations in the area between Oyster Harbour and Cheyne Beach east of Albany. Rapid increases in numbers have occurred in the Mt Manypeaks area in recent years. The whole population has now increased to 10.5 times its size at rediscovery. This paper reviews Noisy Scrub-bird conservation efforts during the 35 years since its rediscovery and focuses on recent progress, population trends, and the current status of the species. Successful conservation management has been based on research into the scrub-bird's biology and ecology and has involved habitat reservation and protection, fire management, population monitoring, and translocation. Scrub-bird conservation has also provided benefits for other threatened species.

Habitat use and management for the Noisy Scrub-bird Atrichornis clamosus

SummaryAfter European settlement, the range of the Noisy Scrub-bird Atrichornis clamosus contracted and only the population at Two Peoples Bay survived. Management policy at Two Peoples Bay Nature Reserve has been one of wildfire prevention, which has created increased areas of suitable habitat for the species. Territories rose from 45 in 1970 to 189 in 1994. Habitat use was assessed by grouping the dominant vegetation associations in each territory in five categories, in descending order of suitability (assessed on breeding and feeding resources): low eucalypt forest, Agonis forest, tall thicket, low thicket and heath. Turnover rates in territory use gave the same habitat rankings. A range of values of Ne (effective population size) was calculated using assumptions about breeding potential of each habitat category. There may be insufficient habitat at Two Peoples Bay for the population to reach an Ne of 500. Successful translocation to Mt Manypeaks, and the establishment of three small populations by birds dispersing from Two Peoples Bay, suggest that an integrated regional population can develop with an Ne well in excess of 500. The management of areas with populations and the corridors linking them must include minimizing the incidence and extent of wildfires.

A field study of Pseudocheirus occidentalis (Marsupialia : Petauridae) I. Distribution and Habitat

Surveys aimed at determining the distribution and habitat of the rare and endangered western ringtail possum (Pseudocheirus occidentalis) were undertaken in south-western Australia during 1990-92. Surveys relied on sightings of animals, or their characteristic faecal pellets or dreys. Habitat descriptions were collected in areas occupied by P. occidentalis to describe the vegetation and topography. Additional information about habitat was collected at subsets of sites to reflect leaf nutrient levels (nitrogen, phosphorus and potassium) of the major food plants, and to reflect the relative senescence of vegetation communities, and their fire and fox-baiting history. The species has a patchy occurrence from the Collie River to Two Peoples Bay, occurring most commonly in coastal or near-coastal forest that includes Agonis flexuosa as a major component. The most inland population occurs at Perup and this is the only known population living in forest without A. flexuosa. Local extinction has been extensive in the inland and northern parts of the original range (as it was known about 1900) and local decline has been patchy and occurred in most decades (1900-89) in different parts of the original range. Analysis of a matrix of relative abundance and habitat variables identified two habitat parameters associated with higher abundance of P. occidentalis: higher levels of nitrogen in foliage of the major food plant and a higher degree of canopy continuity. Hollow abundance was also implicated as a covariate of relative abundance. Assessment of levels of nitrogen, potassium and phosphorus in A. flexuosa leaves indicated that occupied sites tended to have relatively high nutrient levels. The pattern of decline and persistence of populations in different habitats is discussed with respect to environmental factors considered to have changed over the last century.

Diet of the Noisy Scrub-birdAtrichornis clamosusat Two Peoples Bay, South-western Western Australia

The Noisv Scrub-bird Atrichornis clamosus is a small semi-flightless inhabitant of dense scrubs and low forests on the south coast of Western Australia. Between 1961, when the species was rediscovered (Webster 1962) and 1976, A. clamosus was largely confined to the Mt. Gardner area of the Two Peoples Bay Nature Reserve 40 km east of Albany (Smith 1985a). As a result of habitat management (fire exclusion) and translocation of birds to new sites the population index of the species (determined as the number of singing males) had increased from 45 in 1970 to 290 in 1990, and the range spread over about 30 km of coastal and near coastal land (Danks 1991). The population remains vulnerable to wildfire however, and the species is still classified as endangered (Garnett 1992). Knowledge of the dietary requirements of A. clamosus is important in developing a-better understanding of its ecological needs, for managing its habitat and in selecting release areas for the translocation program. John Gilbert, who discovered A. clamosus in 1842 recorded that the stomach contents of specimens he collected consisted of 'Coleoptera and seeds' (quoted in Whittell 1951). The naturalist William Webb. who also took specimens of A. clamosus in the Albany area between 1875 and 1889, considered the bird's food to consist of 'small beetles and other small insects' (Whittell 1943, quoting Webb 1895). Field observations in the Mt. Gardner area in the 1970s showed that A. clamosus is a predominantly terrestrial insectivore foraging in leaf litter, decayed wood and among shrubs and sedges (Smith 1985b). Observations of prey fed to nestlings and analysis of faecal sacs removed from the nest by the female provided information on the diet of nestlings (Smith & Robinson 1976; Smith & Calver 1984). In the latter study, it was found that nestlings were fed a variety of invertebrates from 19 orders plus a few small vertebrates. The most common prey were Araneida (35%), Orthoptera (27%), larvae (15%) and Blattodea (7%) (Smith & Calver 1984). While this information provided a good guide to A. clamosus diet, it was possible that the nestling was being fed a different diet to that taken by adults. The results of a limited study of the diet of adult A. clamosus based on analysis of faecal samples from birds captured during the translocation program are reported here.

Ecology of the Western WhipbirdPsophodes nigrogularisin Western Australia

SummaryThe Western Whipbird Psophodes nigrogularis at Two Peoples Bay is the only known surviving population of the subspecies nigrogularis. The preferred habitat is thicket, a two to three metre high formation of varied floristic composition. Other vegetation associations are used infrequently, although all nests were found in dense heath adjacent to areas of thicket. As with other populations, structure, not floristic composition, was the important factor in habitat selection. In the absence of fire, the population has steadily increased since the mid–1960s and in 1982, was of the order of 100 pairs. Western Whipbirds occupy overlapping home ranges of 10–19 ha with core areas ranging from 1.5–2.4 ha. Pair bonds are long-lasting and the pair maintains its home range from year to year. Each sex has its own distinctive song type and the female frequently joins the male to sing a duet. Clutch size was two and all clutches were started between late July and early September. Incubation lasts 21 days and the nestlings fledge when about 12 days old and stay with their parents for about two months. Some juveniles undergo a post-fledging moult to assume adult plumage. Future conservation of the species is dependent primarily on appropriate management of fire.

Observations on the Biology of the Western Bristlebird Dasyornis longirostris

Since its discovery in 1839, the range of the Western Bristlebird Dasyornis longirostris has declined and the species is only found in the Two Peoples Bay-Waychinicup River area and the Fitzgerald River National Park region. The preferred habitat is closed heath and it is likely that the increased burning of this habitat by Europeans was the main cause of the species' decline. The habitat in both areas is described. The two song types and three alarm notes are described and details of home range size, breeding season and food are given. Changes in the population at Two Peoples Bay Nature Reserve are explained in terms of the changing fire frequency.

Morphology of the Noisy Scrub-bird, Atrichornis clamosus (Passeriformes: Atrichornithidae): Systematic Relationships and Summary

Evidence provided in this monograph supports the conclusion that the genera Atrichornis and Menura are sufficiently distinct for each to be placed in a monotypic family, viz. the Atrichornithidae and the Menuridae. The suborder Menurae, in which these two families are usually placed, should be merged with the suborder Oscines of the Passeriformes as the differences between them are not sufficiently large to justify continued recognition of these two suborders. The Atrichornithidae and the Menuridae are each other's closest relatives, but the evidence available in this monograph does not suggest an especially close relationship to the Ptilonorhynchidae. It is recommended that the Atrichornithidae and the Menuridae be placed in a superfamily, the Menuroidea, of unknown affinities within the Oscines. The Menuroidea do not appear to be primitive within the Oscines. They are not closely related phylogenetically to the Rhinocryptidae of the Tyranni. Reduction in flying ability of the Menuroidea is presumably advanced in the Oscines and is reflected in a number of morphological features of the skeletomuscular system. The extreme terrestrial habits of the species of the Menuroidea, together with the long incubation and fledgling periods of the single annual chick (two in A. ru/escens), may be contributing to their decline. Moreover, the scrub-birds and lyrebirds may be relict remnants of an earlier larger radiation, and are unable to compete successfully with other avian species and/or to cope with recent changes in the environment, such as the introduction of foxes and feral cats. Conservation efforts for the scrub-birds and lyrebirds should consider the morphological and systematic findings presented in this monograph in addition to ecological data, with the suggestion that the undertakings for the Two Peoples Bay population of Atrichornis clamosus serve as a model for future actions. BOCK, W ALTER J. & MARY HEIMERDINGER CLENCH, 1985. Morphology of the Noisy Scrub-bird, Atrichornis clamosus (Passeriformes: Atrichornithidae): systematic relationships and summary. Records of the Australian Museum 37(4): 243-254.

Population and Habitat Selection of the Noisy Scrub-bird, Atrichornis clamosus, 1962-83

The noisy scrub-bird Atrichornis clamosus at Two Peoples Bay was censused, the number of singing males being used as the population index. Incomplete data from 1962 to 1968 suggest that the number of males varied from 40 to 50 during this period. The first rigorous census found 45 males in 1970 and this number increased to 138 in 1983. The most likely reason for this increase is the absence of fire from the area since 1970. Since 1975 the population has expanded out of its headland stronghold to the south-west of Two Peoples Bay to form a subpopulation around Lake Gardner that is well separated from the headland population by roads, firebreaks and a strip of control burnt blocks. The growth of this subpopulation has added a further safeguard to the population. Observations on the vegetation formations (heath, thicket, low forest A and low forest B) used by male noisy scrub-birds on the headland indicate that most of the best habitat (low forest B) is occupied and that an increasing number of males are occupying suboptimal habitat (heath and thicket). There is sufficiently good habitat to the west of Lake Gardner to allow at least 30 additional males to live in the area.

The Noisy Scrub-Bird: An Interim Report

The Noisy Scrub-bird is found only at Two Peoples Bay. Its habitat is the wetter areas of the Jarrah-Marri forest. Males defend their territories throughout the year and play no part in nest building, incubation or feeding the chick. Breeding takes place in winter. If the egg or chick is lost the female may build another nest and re-lay. Only one female is associated with a male territory. The male has two distinct types of song (territorial and short song), a three-noted call and three single call notes. Females normally give only call notes. Mimicry is rare. The population has probably been fairly stable at 44 ± 4 territorial males for at least the last ten years.