Grey-crowned Babbler Pomatostomus Temporalis Research Articles

Roadside habitat connectivity for declining woodland birds in Australian farmland: A case study from the New South Wales South Western Slopes

The decline of birds in farmland is a conservation and land-management issue of global concern. Linear woodland corridors along roadsides in Australian farmland can play an important network role, maintaining ecological connectivity at the landscape scale and thereby supporting the survival of disturbance-sensitive woodland species. This paper presents a case study investigating the connectivity value of Old Narrandera Road, an old (pre-1870) roadside woodland corridor linking three larger woodland remnants near Wagga Wagga, in southern inland New South Wales, Australia. A survey of 120 plots along this corridor during 2018–2019 identified 81 bird species including 25 declining woodland birds of known conservation concern. Presence of the hyper-aggressive Noisy Miner Manorina melanocephala in survey plots was negatively correlated with total species richness and declining woodland bird assemblage richness and several species (predominantly small to medium-sized declining woodland birds rather than common farmland birds) exhibited a degree of spatial separation with Noisy Miners. One decliner, Grey-crowned Babbler Pomatostomus temporalis, showed a significant positive association with Noisy Miner, potentially reflecting a greater tolerance to harassment by Miners. Although the Noisy Miner is probably limiting realisation of the connectivity value of this woodland corridor at present, corridors as substantial and significant as Old Narrandera Road are scarce in the local landscape, and the woodland complex of three interconnected remnants it brings together is likely to be important for the local conservation of many declining woodland bird species.

Inter-sexual differences in contributions of helpers in a tropical population of the cooperatively breeding Grey-crowned Babbler Pomatostomus temporalis

ABSTRACT The Grey-crowned Babbler Pomatostomus temporalis is a group-living, cooperatively breeding species in which offspring of both sexes are equally philopatric, but only male helpers inherit the natal territory. We quantified helping efforts in a tropical population of the babbler, and tested the hypothesis that inter-sexual differences in helping efforts are related to the chance of inheriting their natal territory. We found that the total nest visiting rate during the nestling period and fledging success were higher among larger groups, but dominant birds (breeders) did not decrease their effort with group size. The total nest visiting rate during the nestling period increased with the number of female helpers, and fledging success was higher in groups with a female-biased sex ratio. In contradiction of the above hypothesis, female helpers contributed more towards nestling care than male helpers, although the latter contributed more towards nest building. There was no tendency for helpers to contribute more care towards nestlings of related breeders than those of unrelated breeders, suggesting that indirect (kin selection) benefits for helpers may be less important than direct benefits in explaining helping behaviour in this population. Our study suggests there may be sex-specific differences in the costs and benefits of helping behaviour.

Demographic Effects of Habitat Restoration for the Grey-Crowned Babbler Pomatostomus temporalis, in Victoria, Australia.

BackgroundConsiderable resources are spent on habitat restoration across the globe to counter the impacts of habitat loss and degradation on wildlife populations. But, because of time and resourcing constraints on many conservation programs, the effectiveness of these habitat restoration programs in achieving their long-term goals of improving the population viability of particular wildlife species is rarely assessed and many restoration programs cannot demonstrate their effectiveness. Without such demonstration, and in particular demonstrating the causal relationships between habitat restoration actions and demographic responses of the target species, investments in restoration to achieve population outcomes are of uncertain value.ApproachHere, we describe an approach that builds on population data collected for a threatened Australian bird – the Grey-crowned Babbler Pomatostomus temporalis - to evaluate how effectively targeted habitat restoration work improves its viability. We built upon an extensive historical survey by conducting surveys 13 years later at 117 sites stratified by presence/absence of restoration works and by detection or not of birds in the first survey. Our performance metric was the number of individuals in a social group, which is both a measure of local abundance and directly related to breeding success. We employed an occupancy model to estimate the response of Grey-crowned Babbler social group size to the effects of time, restoration works, local habitat as measured by the density of large trees, and distance to the nearest other known group of babblers.Results and implicationsBabbler group size decreased over the survey period at sites without restoration works, but restoration works were effective in stemming declines where they were done. Restoration was responsible for a difference of about one bird per group of 3-5 individuals; this is an important effect on the reproductive success of the social group. Effectiveness of restoration works targeted at the Grey-crowned Babbler was only demonstrable by sampling through time and including control sites without restoration works. This work demonstrates that while calls for better monitoring of restoration are valid, scope exists to recover a signal of effectiveness from opportunistic retrospective analyses.

What Determines Habitat Quality for a Declining Woodland Bird in a Fragmented Environment: The Grey-Crowned Babbler Pomatostomus temporalis in South-Eastern Australia?

Understanding what constitutes high quality habitat is crucial for the conservation of species, especially those threatened with extinction. Habitat quality frequently is inferred by comparing the attributes of sites where a species is present with those where it is absent. However, species presence may not always indicate high quality habitat. Demographic parameters are likely to provide a more biologically relevant measure of quality, including a species’ ability to successfully reproduce. We examined factors believed to influence territory quality for the grey-crowned babbler (Pomatostomus temporalis), a cooperatively breeding woodland bird that has experienced major range contraction and population decline in south-eastern Australia. Across three broad regions, we identified active territories and determined the presence of fledglings and the size of family groups, as surrogates of territory quality. These measures were modelled in relation to habitat attributes within territories, the extent of surrounding wooded vegetation, isolation from neighbouring groups, and the size of the neighbourhood population. Fledgling presence was strongly positively associated with group size, indicating that helpers enhance breeding success. Surprisingly, no other territory or landscape-scale variables predicted territory quality, as inferred from either breeding success or group size. Relationships between group size and environmental variables may be obscured by longer-term dynamics in group size. Variation in biotic interactions, notably competition from the noisy miner (Manorina melanocephala), also may contribute. Conservation actions that enhance the number and size of family groups will contribute towards reversing declines of this species. Despite associated challenges, demographic studies have potential to identify mechanistic processes that underpin population performance; critical knowledge for effective conservation management.

Social structure and helping behaviour of the Grey-crowned Babbler Pomatostomus temporalis

A 4-year study of cooperative breeding in the Grey-crowned Babbler Pomatostomus temporalis was conducted in the monsoon-tropics of northern Australia. Most groups comprised a single socially monogamous pair with up to seven helpers. We found no floaters. The sex ratio was almost unity for each year. Helpers included philopatric offspring, immigrating juveniles and immigrating sexually mature birds. Adults of both sexes moved frequently between groups. Pairs without helpers were unable to raise young to fledging and often divorced, suggesting that cooperative breeding was obligatory in this population. However, for groups with helpers, the group size effect was weak; there was no significant correlation between the number of fledglings and number of helpers. Breeding females exclusively contributed to incubation. Breeders contributed more to provisioning of nestlings than non-breeders. Although helpers did not enhance the total provisioning rate to nestlings, small groups should recruit helpers to maintain the group and enhance reproductive success.

Communal Building of Brood and Roost Nests by the Grey-Crowned BabblerPomatostomus Temporalis

SUMMARYDOW, D.D. and B.R. KING. 1984. Communal building of brood and roost nests by the Grey-crowned Babbler Pomatostomus temporalis. Emu 84: 193–199.Observations were made on the times of building, the construction and use of nests for breeding and roosting by the communally breeding Grey-crowned Babbler Pomatostomus temporalis in south-eastern Queensland.Activities were recorded at ten nests built by groups numbering from three to nine birds. The breeding pair of a group did more work than all other members, and the breeding female's contribution exceeded the breeding male's. Among auxiliary members, older birds did more work than younger ones. With increasing group size, the breeding female's visiting rate and her percentage contribution to building tended to remain constant, while the breeding male's rate and percentage decreased linearly. With increasing group size, the overall building rate of groups decreased slightly, possibly due to lack of co-ordination in the activities of larger groups, but mainly because of decreased effort by the primary male.Nests under construction were occasionally used as roosts; on completion, nests were used for either roosting or breeding, depending on the time of year. Nests used for breeding were afterwards used as roosts. Repeated repair of old nests caused these to become enlarged, but still of the same basic construction as new nests.Roles in building and in feeding nestlings are compared among birds of different social status. The differential effort of the primary female is most obvious.

Social Organization and Behaviour of the Grey-Crowned BabblerPomatostomus Temporalis

SUMMARYKing, B. R. 1980. Social organization and behaviour of the Grey-crowned Babbler Pomatostomus temporalis. Emu 80: 59–76.The social system of wild and captive Grey-crowned Babblers Pomatostomus temporalis was studied in south-eastern Queensland. Three classes of age were distinguished on colour of iris and a fourth by difference in plumage. Adult birds could be sexed by length of bill. The ratio of males to females in a population did not differ significantly from unity. The species occurred in sedentary territorial groups, each of which usually contained a single breeding pair and a number of non-breeding birds. Non-breeding members were of all ages and mostly the offspring of previous broods of the breeding pair. Groups moved as closely knit units and much behaviour was directed towards cohesion of the group. Patterns of behaviour and calls are described. Groups were strongly territorial and spent much time in disputes with neighbouring groups. In general, size of home range did not directly correlate with size of group. All members of a group co-operate in building and care of the young but only the breeding female incubates and broods. The degree of participation of an individual in visiting nests and feeding young usually corresponds with its age and status within the group.