Michael F. Clarke

Large-scale bird-movement patterns evident in eastern Australian atlas data

Abstract Ad hoc studies of the compositions of bird communities at dispersed sites and bird-banding data have failed to reveal the timing, destinations and movement patterns of most Australian migratory bird species. The analysis of national atlas and count data, on the other hand, has the potential to provide information on the species undertaking migratory movements, the timing of these movements, and their sources and destinations. This study examines atlas data of 407 species for evidence of movements by these species in eastern Australia. Atlas and bird-count data were brought together to form the most extensive collection of bird observations in Australia. Mathematical, statistical and graphical tools were used to examine these data for evidence of temporal changes in the spatial distributions of each species. Examples are provided of the application of these tools to four speices (Dollarbird, Eurystomus orientalis, Noisy Miner, Manorina melanocephala, Grey Fantail, Rhipidura fuliginosa and the Budgerigar, Melopsittacus undulatus) that exhibit varying movement patterns. A standardised analysis applying these indicators across 407 species found strong evidence of migratory movements for 101 of these species and suggestive evidence for a further 45 species. These results indicated 19 distinctive patterns of migration among the birds of eastern Australia.

Ageing mallee eucalypt vegetation after fire: insights for successional trajectories in semi-arid mallee ecosystems

A critical requirement in the ecological management of fire is knowledge of the age-class distribution of the vegetation. Such knowledge is important because it underpins the distribution of ecological features important to plants and animals including retreat sites, food sources and foraging microhabitats. However, in many regions, knowledge of the age-class distribution of vegetation is severely constrained by the limited data available on fire history. Much fire-history mapping is restricted to post-1972 fires, following satellite imagery becoming widely available. To investigate fire history in the semi-arid Murray Mallee region in southern Australia, we developed regression models for six species of mallee eucalypt (Eucalyptus oleosa F.Muell. ex. Miq. subsp. oleosa, E. leptophylla F.Muell. ex. Miq., E. dumosa J. Oxley, E. costata subsp. murrayana L. A. S. Johnson & K. D. Hill, E. gracilis F.Muell. and E. socialis F.Muell. ex. Miq.) to quantify the relationship between mean stem diameter and stem age (indicated by fire-year) at sites of known time since fire. We then used these models to predict mean stem age, and thus infer fire-year, for sites where the time since fire was not known. Validation of the models with independent data revealed a highly significant correlation between the actual and predicted time since fire (r = 0.71, P  35 years since fire). Nevertheless, this approach enables examination of post-fire chronosequences in semi-arid mallee ecosystems to be extended from 35 years post-fire to over 100 years. The predicted ages identified for mallee stands imply a need for redefining what is meant by ‘old-growth’ mallee, and challenges current perceptions of an over-abundance of ‘long-unburnt’ mallee vegetation. Given the strong influence of fire on semi-arid mallee vegetation, this approach offers the potential for a better understanding of long-term successional dynamics and the status of biota in an ecosystem that encompasses more than 250 000 km2 of southern Australia.

Complex social organization reflects genetic structure and relatedness in the cooperatively breeding bell miner, Manorina melanophrys

The cooperatively breeding bell miner, Manorina melanophrys, differs from most other cooperative breeding species in the complexity of its social system, where discrete social organization occurs on at least three levels. Microsatellite markers were used to investigate the degree of genetic structure underlying the social organization of M. melanophrys by comparing colonies, coteries and nest contingents. The genetic data confirmed behavioural observations of M. melanophrys living in male kin‐based groups between which females disperse short distances to breed. Estimates of FST revealed restricted gene flow between eight colonies located within 30 km that was significantly associated with geographical distance when the two most distant colonies were included. Within a high density colony significant differences were found between coteries; analysis of the degree of relatedness between coterie members showed that this is due to related individuals associating preferentially with each other. Similarly, the contingent of individuals attending a nest were generally close relatives of the young they were aiding, supporting models invoking kin selection as the selective agency mediating helping.

Primary sex ratio bias in an endangered cooperatively breeding bird, the black-eared miner, and its implications for conservation

The aim of our study was to investigate primary and adult sex ratios in the cooperatively breeding black-eared miner, Manorina melanotis. We used genetic methods to determine the sex of all birds. Observations were made to quantify differences in helping behaviour between the sexes. As in other miners, Manorina spp., non-breeding males provided most of the help in raising young. Male and female nestlings did not differ significantly in weight, suggesting that both sexes are equally costly to produce. Like other miners, the adult sex ratio in black-eared miners is male-biased (64.4%). However, unlike its congeners, the black-eared miner’s primary sex ratio was strongly biased toward females (62.5%). This suggests that females suffer higher juvenile mortality than males. Our study illustrates how understanding sex ratios is both of theoretical interest and relevant to biological conservation.

Paternity and the Relatedness of Helpers in the Cooperatively Breeding Bell Miner

We used multi-locus DNA fingerprinting to determine the parentage of 13 broods of Bell Miner (Manorina melanophrys) nestlings. Despite very large contingents of male helpers attending individual nests and living in close proximity to breeding females, we found only one instance of extra-pair paternity in 24 nestlings. The genetic father of the extra-pair nestling was not among the males in our study population. The majority of helpers (67% of 52 cases) were close relatives (r > 0.25) of at least one parent of the brood being provisioned. Helpers were more often closely related to the male than the female parent. Only 17% of cases involved helpers that were apparently unrelated to either of the parents of the broods being aided. We conclude that Bell Miners do not mate promiscuously and that the majority of helpers are close relatives of the breeding pair. Cooperative breeding in Bell Miners seems to have evolved as a system of collateral kinship among the breeding birds and helpers.

Fire Mosaics and Reptile Conservation in a Fire-Prone Region

Fire influences the distribution of fauna in terrestrial biomes throughout the world. Use of fire to achieve a mosaic of vegetation in different stages of succession after burning (i.e., patch-mosaic burning) is a dominant conservation practice in many regions. Despite this, knowledge of how the spatial attributes of vegetation mosaics created by fire affect fauna is extremely scarce, and it is unclear what kind of mosaic land managers should aim to achieve. We selected 28 landscapes (each 12.6 km(2) ) that varied in the spatial extent and diversity of vegetation succession after fire in a 104,000 km(2) area in the semiarid region of southeastern Australia. We surveyed for reptiles at 280 sites nested within the 28 landscapes. The landscape-level occurrence of 9 of the 22 species modeled was associated with the spatial extent of vegetation age classes created by fire. Biogeographic context and the extent of a vegetation type influenced 7 and 4 species, respectively. No species were associated with the diversity of vegetation ages within a landscape. Negative relations between reptile occurrence and both extent of recently burned vegetation (≤10 years postfire, n = 6) and long unburned vegetation (>35 years postfire, n = 4) suggested that a coarse-grained mosaic of areas (e.g. >1000 ha) of midsuccessional vegetation (11-35 years postfire) may support the fire-sensitive reptile species we modeled. This age class coincides with a peak in spinifex cover, a keystone structure for reptiles in semiarid and arid Australia. Maintaining over the long term a coarse-grained mosaic of large areas of midsuccessional vegetation in mallee ecosystems will need to be balanced against the short-term negative effects of large fires on many reptile species and a documented preference by species from other taxonomic groups, particularly birds, for older vegetation.

Characterization of microsatellite loci for a co-operatively breeding honeyeater.

presence of nonbreeding nest attendants ‘helping’ to feed a bird that is neither its mate nor its dependant offspring (Skutch 1961). The relationships between the donors and recipients of such aid are generally estimated by pedigrees constructed from behavioural observations. However, in order to accurately estimate relatedness, determination of genetic parentage is required, as in co-operatively breeding species there may a number of potential breeders present at each nest. The bell miner Manorina melanophrys is a behaviourally monogamous species in which a number of individuals of varying relatedness to the breeding pair help to provision nestlings. We have characterized five microsatellite loci to investigate the mating system of the bell miner, and surveyed the utility of these loci in other species of Meliphagidae. DNA was extracted from muscle tissue using a proteinase K-phenol : chloroform-ethanol extraction procedure (Sambrook et al. 1989). Three distinct partial genomic libraries were constructed from Sau3AI, Sau3AI/RsaI and Sau3AI/HaeIII digested DNA. The DNA was ligated to either BamHI (Sau3AI digested DNA), or BamHI/HincII (double-digested DNA) digested pUC19 vector (New England Biolabs). The three libraries, totalling ≈ 80 000 clones, were probed with a cocktail of four simple sequence repeat motifs; (GT)10; (CT)10; (AAC)10 and (CCT)10 previously end-labelled with [γ33P]-ATP using T4 polynucleotide kinase (New England Biolabs). Positive clones were detected in all libraries. The DNA inserts from 32 clones were amplified directly from lysed bacterial cells and then sequenced with [γ33P]-ATP end-labelled M13 forward and reverse universal primers. The inserts ranged in size from 300 bp to 1 kb, and all contained (GT)n repeats. Primers were developed for 15 loci with at least 10 uninterrupted repeats. DNA for microsatellite analysis was extracted from blood preserved in Queens lysis buffer (Seutin et al. 1991). One primer from each pair was end-labelled with [γ33P]ATP. For all loci the 10 μL PCR reaction contained 10 mM Tris-HCl, 50 mM KCl, 0.1 unit Taq polymerase (Promega), 0.2 pmol labelled primer, 0.5 pmol unlabelled primer, 2.0 mM MgCl2, 200 μM each dNTP, 10 μg BSA and 20–50 ng template DNA. The PCR profile for all loci was an initial denaturation step for 2 min at 92 °C, an annealing step of 30 s at 55 °C (60 °C for BMC3), and an extension step of 30 s at 72 °C. This was followed by 29 cycles of 30 s at 92 °C, 30 s at 55 °C (60 °C for BMC3) and 30 s at 72 °C. Amplified fragments were resolved using 6% denaturing polyacrylamide gels. Each gel was loaded twice enabling more samples to be resolved per gel by allowing sufficient time between the first and second loadings to ensure the samples did not overlap. Allele lengths were estimated initially by comparison to a lambda gt11 sequence ladder (Promega), and subsequently to an allelic ladder comprising samples encompassing the range of allele lengths for the particular locus. Of the 15 loci tested five were polymorphic in the bell miner, having between three and 11 alleles and heterozygosities ranging from 25 to 74% (Table 1). For these allele frequencies, using all loci yields a probability of 8 × 10–2 of a complete allelic match between helpers and nestlings. Helpers are generally related to the individuals of the nest they attend, but 78% of female attendants and 88% of male attendants were eliminated as parents of the nestlings they were helping to feed. These loci have provided the first molecular evidence of intraspecific brood parasitism reported for any honeyeater (J. Painter, unpublished data). The five polymorphic loci were tested in nine other honeyeater species. The PCR conditions for all loci were as detailed above, except that the MgCl2 concentration was decreased to 1.5 mM and the BMC3 primer annealing temperature decreased to 55 °C. A product was obtained for all species for all loci with the exception of BMC5 for one Phylidonyris species (Table 2). The only apparent predictor of variability in the nonsource species was the amount of nonspecific amplification product coamplified with the microsatellite loci (as noted by Primmer et al. 1996). Cross-amplifiable microsatellite loci should foster the study of honeyeaters in general. Honeyeaters are of P R I M E R N O T E

The short-term responses of small mammals to wildfire in semiarid mallee shrubland, Australia

Context. Wildfire is a major driver of the structure and function of mallee eucalypt- and spinifex-dominated landscapes. Understanding how fire influences the distribution of biota in these fire-prone environments is essential for effective ecological and conservation-based management. Aims. We aimed to (1) determine the effects of an extensive wildfire (118 000 ha) on a small mammal community in the mallee shrublands of semiarid Australia and (2) assess the hypothesis that the fire-response patterns of small mammals can be predicted by their life-history characteristics. Methods. Small-mammal surveys were undertaken concurrently at 26 sites: once before the fire and on four occasions following the fire (including 14 sites that remained unburnt). We documented changes in small-mammal occurrence before and after the fire, and compared burnt and unburnt sites. In addition, key components of vegetation structure were assessed at each site. Key results. Wildfire had a strong influence on vegetation structure and on the occurrence of small mammals. The mallee ningaui, Ningaui yvonneae, a dasyurid marsupial, showed a marked decline in the immediate post-fire environment, corresponding with a reduction in hummock-grass cover in recently burnt vegetation. Species richness of native small mammals was positively associated with unburnt vegetation, although some species showed no clear response to wildfire. Conclusions. Our results are consistent with the contention that mammal responses to fire are associated with their known life-history traits. The species most strongly affected by wildfire, N. yvonneae, has the most specific habitat requirements and restricted life history of the small mammals in the study area. The only species positively associated with recently burnt vegetation, the introduced house mouse, Mus domesticus, has a flexible life history and non-specialised resource requirements. Implications. Maintaining sources for recolonisation after large-scale wildfires will be vital to the conservation of native small mammals in mallee ecosystems.

Interactions between the superb lyrebird (Menura novaehollandiae) and fire in south-eastern Australia

Abstract Context. The superb lyrebird Menura novaehollandiae is thought to be an important ecosystem engineer that, through its foraging, accelerates the decomposition of litter in Eucalyptus forests. Lyrebird foraging is therefore likely to affect forest fuel loads and hence fire behaviour in these fire-prone forests. In turn, fire is likely to reduce the abundance and influence the distribution of lyrebirds. Aims. Our goal was to determine the impacts of a major bushfire on the habitat and food sources for the superb lyrebird and the effects of foraging activities of lyrebirds on litter fuel and potential fire behaviour in gullies of herb-rich foothill forests. Methods. The effect of fire on lyrebirds and their habitat in the post-fire environment was examined at the landscape-scale, 2 years after fire; and at the patch-scale, 3 years after fire. Paired exclusion and control plots were also used over a 9-month period to assess the effects of foraging by the lyrebird on litter accumulation and fuel connectivity. Fire-behaviour models were used to determine the potential influence of lyrebird scratchings on fire behaviour. Key results. At the landscape scale, lyrebirds were present in both unburnt and ground-burnt sites, but not in canopy-burnt sites. Within patchily burnt sites, lyrebirds favoured foraging in unburnt patches. On average, lyrebird foraging reduced litter fuel loads by 25% (1.66 t ha–1) in plots in which they were free to forage, compared with plots from which they were excluded, over a 9-month period. Fire-behaviour modelling showed that lyrebird foraging led to a lower likelihood of fire occurring and less intense fire. Conclusions. Distinctly different vegetation structure and composition between burnt and unburnt patches appears to influence both the foraging patterns and distribution of lyrebirds. Additionally, foraging by lyrebirds reduces surface fuel loads and fuel connectivity such that fire spread is likely to be inhibited. Implications. We propose that alternative stable states may emerge in Eucalyptus forests as a result of feedback mechanisms among lyrebirds, vegetation and fuel accumulation. Therefore, the ecological role of lyrebirds is an important consideration in forest fuel management and conservation in these extensive, fire-prone forests in south-eastern Australia.

Intraspecific phenotypic variability in the black-eared miner (Manorina melanotis); human-facilitated introgression and the consequences for an endangered taxon

Prior to this study the circumscription of the endangered black-eared miner (Manorina melanotis) and the common yellow-throated miner (Manorina flavigula) has been clouded by the existence of hybrid individuals. We examined the intra- and inter-specific phenotypic variation of the two taxa. All available museum specimens (n=138) and a sample of live individuals (n=83) were examined. Cluster analysis revealed a continuum of phenotypic traits now exists between the two taxa. However, further analysis revealed the black-eared miner and yellow-throated miner were separable on phenotypic characters prior to extensive modification of mallee habitat after 1950, suggesting the black-eared miner should be afforded full species status [contrary to Schodde and Mason, 1999. (Schodde, R., Mason, I.J., 1999. The Directory of Australian Birds: Passerines. CSIRO Wildlife and Ecology, Canberra]. Our study highlights the need to carefully examine, not only intraspecific phenoptyic variation within a taxon, but to also consider how such variation may be affected by hybridisation facilitated by human disturbance of habitat.