Climacteris Rufa Research Articles

Impact of a prolonged decline in rainfall on eucalypt woodlands in southwestern Australia and its consequences for avifauna

Aims Our objective was to establish a relationship between long-term variation in the climatic environment, tree canopy decline and observed effects on the population dynamics of avifauna in the Dryandra Woodlands in southwestern Australia. These geographically isolated remnant woodlands are rich in endemic species and sustain a diverse range of ecological communities, but are threatened by habitat degradation and a decline in rainfall. Methods We used annual rainfall data, averaged from a series of weather stations within 100 km of the Dryandra Woodlands and a time series analysis to investigate long-term changes in annual rainfall. Satellite spectral observations of eight study sites at Dryandra was used to measure changes in Projected Foliage Cover (PFC) of old growth Eucalyptus wandoo at all sites. Our mist-net trapping study across three years and all eight sites, targeted two focal species; the rufous treecreeper (Climacteris rufa) and yellow-plumed honeyeater (Ptilotula ornata). We investigated the relationship between the captures of each species and variation in PFC, between sites and across years. Also in a separate demographic study, capture-mark-recapture data was used to estimate the apparent survival rate of each species, following the robust design for open and closed populations. Key results We demonstrate a long-term and continuing decline in average annual rainfall that is accelerating. We found the rainfall trend is concomitant with a long-term decline in PFC of E. wandoo and that the previous year’s annual rainfall is a predictor of average PFC across all sites. Additionally, we discovered that the PFC at each site, in each year, is a predictor of the number of yellow-plumed honeyeaters which prefer feeding on canopy insects and not a predictor of the predominantly ground-foraging rufous treecreeper. We also found a substantial difference in the apparent survival rates between the two species, with the apparent survival of yellow-plumed honeyeaters being approximately half that of rufous treecreepers. This difference was partially attributed to the likely movement outside of the study area due to decreasing habitat quality. Conclusions and implications Overall, our results do suggest that some impacts of long-term rainfall trends can be traced to particular species through PFC variation, but the response between species to habitat change will differ and depend on species-specific habitat requirements. As increasing greenhouse emissions are associated with declining rainfall in southwestern Australia, this study shows if rainfall decline and habitat degradation continue, it will have catastrophic consequences for woodland ecosystems.

Do woodland birds prefer to forage in healthy Eucalyptus wandoo trees?

Globally, many forests and woodlands are in decline. The marked loss of canopy foliage typical of these declines results in reduced foraging resources (e.g. nectar, pollen, and insects) and, subsequently, can reduce habitat quality for woodland birds. In south-west Western Australia, patches of Eucalyptus wandoo woodlands have shown a decline in condition since at least 2002. We investigated how changes in E. wandoo condition affect the woodland bird community. Foraging activities of three bird species were recorded for 20 sites in Dryandra State Forest and Wandoo Conservation Park either by conducting watches on focal trees (‘sitting’ method), or following individuals through the woodland (‘following’ method). Condition assessments of trees used by the birds were compared with those for trees available at the study site. Weebills (Smicrornis brevirostris; canopy insectivore) displayed preference for healthy trees (low amounts of canopy dieback), whereas rufous treecreepers (Climacteris rufa; bark-foraging insectivore) preferred trees with a higher proportion of dead branches. Yellow-plumed honeyeaters (Lichenostomus ornatus; insectivore/nectarivore) foraged in older, larger E. wandoo trees having full canopies with few signs of tree decline. Tree declines, such as that happening in E. wandoo, alter the foraging resources and habitat available to woodland birds.

The ecology of the rufous treecreeper in the jarrah forest of south-western Australia and implications for its conservation and management

Rufous treecreepers (Climacteris rufa) are common in southern jarrah forests of Western Australia, but nothing has been recorded of their ecology in the region. I investigated the foraging and nesting ecology of the species in the southern jarrah forests from January 1994 to April 1996. Rufous treecreepers foraged exclusively on two eucalypt species, jarrah and marri, and foraged on trees that were significantly larger and taller than random. Foraging on the ground, logs and fallen trees was relatively infrequent. Nest hollows were also located exclusively in jarrah and marri trees that were significantly larger and taller than random. The important foraging and nesting resources for the species in the southern jarrah forest appear to be large mature and overmature eucalypts. Anthropogenic impacts in the region, primarily logging, should aim to retain these resources in affected areas to improve the survival prospects of the species. When compared with studies in wandoo woodlands, the results of the present study indicate that the conservation of ground-layer habitat is likely to be of less importance in the jarrah forest. These habitat differences indicate that site-specific information is critical if the management and conservation of individual species is to be effective.

Comparative Ecology of Four Passerine Species in Jarrah Forests Used for Timber Production in Southwestern Western Australia

Abstract: I assessed which resources were critical for bird species that decline after selective logging. I compared foraging and nesting behaviors of Western Yellow Robins ( Eopsaltria griseogularis), Rufous Treecreepers (Climacteris rufa), Golden Whistlers ( Pachycephala pectoralis), and White‐naped Honeyeaters ( Melithreptus lunatus) before and after logging in jarrah forests used for timber production in southwestern Australia. Species that declined after logging (Golden Whistler, White‐naped Honeyeater) foraged in the canopy and displayed little flexibility in foraging behavior. Species that did not decline ( Western Yellow Robin, Rufous Treecreeper) foraged lower, spent a variable proportion of time on the ground and displayed greater flexibility in foraging behavior. Rufous Treecreepers, obligate tree‐hollow nesters, and Western Yellow Robins did not alter nesting sites after logging, but Golden Whistlers nested infrequently in logged areas. There were no consistent differences in the nesting ecologies of the two groups, and it is unclear why Golden Whistlers nested infrequently in logged forest. Western Yellow Robins and Rufous Treecreepers used logged forest as frequently after logging as before and did not appear to require unlogged buffers to persist in forests used for timber production. In contrast, Golden Whistlers used logged forests less frequently after logging and moved their territories to include unlogged buffers. Retention of critical resources for Golden Whistlers and White‐naped Honeyeaters in logged forest is unlikely to be feasible because of the effects on timber yield, emphasizing the importance of unlogged buffers in forest management.

Determining habitat quality for the cooperatively breeding Rufous Treecreeper, Climacteris rufa

Abstract The theory of habitat selection predicts that organisms should use habitat that maximizes their fitness. The cooperatively breeding Rufous Treecreeper, Climacteris rufa, exhibits non‐random habitat use at a number of spatial scales. By assessing correlative relationships between nest‐site use and nest success, and territory use and reproductive success and survival, it was determined whether non‐random use of habitat yields fitness benefits. It was also determined whether breeding group size contributed significantly to fitness once differences in territory quality had been considered. Structural characteristics of nest sites that were positively correlated with the probability of a site being used had no relationship with nest success. This result probably reflects the relatively unrestricted access to an abundance of suitable nest sites in the study area. Habitat traits that predicted territory use by treecreepers were positively correlated with a number of fitness measures. They were also positively correlated with breeding group size and provisioning rate to nestlings, which in turn were correlated with fitness. However, group size was not significantly related to any measure of fitness, except primary male survival, once territory quality had been considered. The quality of territories occupied by Rufous Treecreepers appeared to be a significant factor for breeding group fitness.

Differences in the reproductive success and survival of the rufous treecreeper ( Climacteris rufa) between a fragmented and unfragmented landscape

The rufous treecreeper ( Climacteris rufa) has declined in abundance in the agricultural regions of southwestern Australia. The patterns of decline are well documented, but the processes that threaten population persistence are poorly understood. I compared the reproductive success and survival of the treecreeper between three sites in an unfragmented landscape and four remnant categories (large, small, grazed and ungrazed) in a fragmented, agricultural landscape. Nest success and annual productivity were significantly higher in the unfragmented landscape, but varied between sites and remnant categories within landscapes. Nest success was lowest in grazed remnants and annual productivity was positively associated with territory size in the fragmented landscape. Fledgling survival rates did not differ between landscapes, but there was a trend for juvenile survival rates to be higher in the unfragmented landscape. I used artificial nests to compare relative predation rates between landscapes, and provisioning rates and prey biomass brought to nestlings to assess differences in food availability. There were no landscape differences in predation rates, but provisioning rates to nestlings and total prey biomass were significantly lower in the fragmented landscape. Mean habitat quality was also lower in the fragmented landscape, although it differed between remnant categories. Reduced reproductive success, juvenile survival, food availability and habitat quality may threaten the viability of the rufous treecreeper population living in the fragmented landscape. Limiting the modification of remaining habitat (e.g. removing stock grazing) and improving habitat quality are required to assist in the conservation of this species.

The habitat requirements of the rufous treecreeper (Climacteris rufa). 1. Preferential habitat use demonstrated at multiple spatial scales

Determining the habitat requirements of a species is fundamental to effective conservation, particularly if the species is declining in areas where its habitat is being modified. Multi-scaled investigations of habitat use are essential because different selection processes may operate at different scales. I examined the habitat use of a declining woodland passerine, the rufous treecreeper (Climacteris rufa), at three spatial scales (landscape, woodland and territory) in the wheatbelt of Western Australia. Preferential habitat use was exhibited at all scales. At the landscape scale, wandoo (Eucalyptus wandoo) woodland was used at a significantly greater rate than three other common vegetation types. Territory use within woodlands was positively related to the density of hollow-bearing logs, the density of nest sites, and tree age. Within an individual territory, nest sites (hollows) were favoured if they had a spout angle of ⩾50° to the horizontal and an entrance size of between 5 and 10 cm. The rufous treecreeper preferentially used habitat with traits characteristic of old-growth wandoo woodland. Degradation of wandoo through habitat modification (e.g. grazing, logging, fire and removal of deadwood) represents a significant threat to the persistence of treecreepers.

The habitat requirements of the rufous treecreeper (Climacteris rufa). 2. Validating predictive habitat models

Examining the predictive capability of statistical models with data independent from that used to derive the model is a vital step in the iterative procedure of assessing model performance. I derived logistic regression models of the habitat use of the rufous treecreeper (Climacteris rufa) at two spatial scales: woodland (territory selection model) and territory (nest-site selection model). The performance of these models was assessed in relation to the original data collected and validated with new, independent data. When applied to the original data, the territory model had a high predictive capability correctly classifying 90% of sites (n=100) that were either occupied or unoccupied by treecreepers. Correct classification rate was reduced to 70% (n=50) when the model was applied to the validation data. Model performance was generally robust when probability of occurrence values for the species were varied. In contrast, the nest-site model had lower predictive capabilities correctly classifying between 66 and 68% of sites, and performed relatively poorly when probability values were varied. The performance of the models differed slightly between the original and validation data, and substantially between the spatial scales examined. Territory use by rufous treecreepers could be predicted with some confidence indicating that the territory model may be a useful tool for habitat management. Nest-site use could not be predicted with confidence probably as a result of the high abundance of suitable, but unused, nest sites in the study area.

The dynamics and conservation of a spatially subdivided avian population in a fragmented landscape

Many bird species have declined in abundance in the agricultural regions of southern Australia, The mechanisms underlying these declines and the viability of the remaining populations are largely unknown, A number of species exist as spatially subdivided populations in heavily fragmented landscapes. Metapopulation and source-sink theory have influenced thinking on the dynamics of subdivided populations, but the general applicability of these theories is uncertain. I examined the dynamics of a subdivided population of the Rufous Treecreeper Climacteris ruta, a declining woodland passerine, occupying a fragmented, agricultural landscape in southwestern Australia. I determined if local populations could replace themselves without immigration and estimated population growth rates for the periods 1998-1999 and 1999-2000. I also examined the influence of movement between local populations on the viability of the entire subdivided population. Out of four geographically defined local populations, only one was above replacement, and only in one year of the study. Fledgling productivity and recruitment in the remainder were not sufficient to compensate for breeding female mortality. Long-term population growth estimates were <1 for all local populations, but variability in demographic rates suggested that the status of these populations may fluctuate over time. Also, there appeared to be sufficient movement between local populations, and into the study area from nearby habitat remnants, to slow or halt any decline in local population size, Within- and between-local-population processes appeared to be important to the viability of the treecreeper population during the two years of the study, and this is consistent with the general principles of metapopulation theory. I compared the dynamics of the treecreeper population occupying the fragmented landscape with one occupying a continuously wooded landscape and found that the latter had population growth rates >1, suggesting it may be an important population source and vital to the regional viability of the species.

Variability in provisioning rates to nestlings in the cooperatively breeding Rufous Treecreeper, Climacteris rufa

Provisioning rates to nestlings by adult birds may be influenced by many factors. In cooperatively breeding species, an increase in the number of helpers at the nest may increase total provisioning rate, but in some cases certain individuals will reduce their provisioning effort so that overall provisioning rate does not change with the number of provisioners. I examined numerous environmental and demographic factors that may correlate with provisioning rate in the cooperatively breeding Rufous Treecreeper, Climacteris rufa, in the south-west of Western Australia. A total of 102 nest watches of colour-banded birds was conducted over 3 years. Provisioning rate per hour varied from 8 to 50 (mean ± s.e = 21.8 ± 0.91). There were significant positive relationships between provisioning rate and number of nestlings and nest stage, and negative associations with time of day and maximum daytime temperature. Provisioning rate was highest when there were two nestlings and nestlings were near fledging, early in the morning (before 09:00 hours) and during mild temperatures (20–30°C). There was no relationship between provisioning rate and the number of helpers at the nest because the primary (assumed to be breeding) male and female reduced their provisioning effort as the number of helpers increased.

The demography and cooperative breeding behaviour of the rufous treecreeper, Climacteris rufa

I examined the demography and cooperative breeding behaviour of the rufous treecreeper, Climacteris rufa, in the south-west of Western Australia. Social organisation, breeding behaviour, reproductive success, survival and dispersal were measured over 3 years. The species lived in cooperatively breeding groups of 2–7 individuals, which occupied a territory year round. Most groups comprised a primary male and female (probably breeding) and offspring from previous breeding seasons (helpers). Territory defence was variable, particularly during the breeding season when individuals would feed nestlings in adjacent territories. The social organisation of the species was based on neighbourhoods of interacting territories. All group members provisioned nestlings, and the primary male and female significantly reduced their provisioning effort as the number of helpers increased. Total nest success for the 3 years was 78% and mean annual productivity was 2.1 (0.18). Fledgling and juvenile survival rates were relatively high (0.76 and 0.46 respectively), but adult survival rate (0.76) was comparable to that of other passerines of the temperate Southern Hemisphere. Dispersal of juveniles appeared to be female-biased. The demography of the rufous treecreeper was consistent with other old endemic Australian passerines. High adult survival resulted in few breeding vacancies for non-breeders and this is probably an important factor in the evolution of cooperative breeding in the species. Cooperative breeding also appears to be influenced by habitat saturation and a cost–benefit trade-off between remaining as a helper in high-quality territories and dispersing to poorer-quality territories where reproductive success may be low.

Seasonal and landscape differencesin the foraging behaviour of the Rufous Treecreeper Climacteris rufa

The insectivorous Rufous Treecreeper Climacteris rufa has declined in abundance in the agricultural regions of southwestern Australia. Examining its foraging behaviour is fundamental to identifying important foraging resources and how landscape change (e.g., fragmentation and disturbance) may affect foraging effectiveness. We studied seasonal and landscape differences in the foraging behaviour of the treecreeper in the wheatbelt of Western Australia. Foraging data were collected in autumn and winter in a large, unfragmented landscape and in a highly modified agricultural landscape (winter only) with grazed and ungrazed woodland patches. The ground layer was the most common foraging location used by the species, although there were seasonal differences in foraging behaviour in the unfragmented landscape. In autumn, treecreepers foraged primarily on trees (56% of observations) with a shift to mostly ground foraging in winter (72-74%). The species also preferentially foraged on larger trees. Foraging behaviour differed between the two landscapes within the same season. Treecreepers foraged less on the ground in the agricultural landscape (52%), but this difference is attributed mainly to the low percentage of ground foraging in ungrazed (43%) compared to grazed (60%) patches. In winter and early spring, the ground layer is an important foraging substrate for the Rufous Treecreeper and other woodland birds. Changes to the ground layer and associated invertebrate communities through habitat disturbance (e.g., weed invasion) may be detrimental to the foraging effectiveness of ground-foraging insectivores. This is a potential contributing factor to the decline of these species in the agricultural regions of southern Australia.

The Relationships of the Australo-Papuan Treecreepers Climacteridae as Indicated by DNA-DNA Hybridization

The technique of DNA-DNA hybridization was used to compare the nuclear DNAs of the Brown Treecreeper Climacteris picumnus and the Rufous Treecreeper Climacteris rufa with the DNAs of other passerine taxa. The treecreepers were found to be the descendants of the oldest dichotomy (ca. 45-48 MYA) in the superfamily Menuroidea, a group that also includes the lyrebirds, scrub-birds, and bowerbirds. We recognize the family Climacteridae, superfamily Menuroidea, parvorder Corvi, suborder Passeres. Within the Climacteridae we recognize two genera, Climacteris for the species picumnus, rufa, melanura, erythrops, and affinis, and Cormobates for leucophaea (including minor) and placens.

Distribution and Taxonomy of Southern Birds in the Great Victoria Desert

Certain birds, usually associated with the mallee and sclerophyllous woodlands of south-western Australia, south-eastern Australia and Eyre Peninsula, also occur in the Great Victoria Desert, viz Glossopsitta porphyrocephalu, Neophema splendida, Cinclosoma castonotum, Myiagra inquieta, Microeca leucophaea, Pachysephala inortata, Climacteris rufa, Pardalotus xanthopygus, Strepera versicolor and Gymnorhina tibicen. The distribution, habitats and subspecific status of these species are discussed. The Great Victoria Desert is an avenue for the continuous distribution of these birds between Eyre Peninsula and the Southwest. Populations of most of these species on the eastern and western sides of the Nullarbor Plain have not diverged subspecifically from one another.