Eastern Yellow Robin Eopsaltria Australis Research Articles

Natal dispersal, philopatry and cooperative breeding in Eastern Yellow Robin Eopsaltria australis

ABSTRACT Delayed natal dispersal is thought to have evolved in response to survival benefits of philopatry and group formation under environmental and/or demographic constraints, with kin selection subsequently promoting the emergence of cooperative breeding behaviours. We studied sociality and natal and breeding dispersal of a colour-banded population of Eastern Yellow Robin Eopsaltria australis over 10 years to better understand the evolution of facultative cooperative breeding in this long-lived, territorial songbird. Breeding group size averaged 3.08 (range 2–6) adults and 82% of helpers were males. All male young delayed dispersal to help one or both parents (82.1%), another first order relative (12.5%) or other relatives (5.4%) for between one and four years before establishing as a dominant breeder. The social relationships of female helpers was confirmed in only two instances, with the helper being the daughter of the breeding pair. Helpers significantly increased annual productivity, which averaged 1.44 (95% confidence intervals: 1.07–1.81) with no helpers and 2.04 (95% confidence intervals: 1.74–2.34) with helpers present. Male young were highly philopatric; most either inherited the natal territory or budded off a portion of the natal territory, and none dispersed more than one territory away. Most females appeared to disperse further after reaching independence to become floaters. Breeding dispersal was limited to females, who dispersed after either divorce or to avoid incest once a son inherited the territory. These results confirm that Eastern Yellow Robin helpers likely gain indirect fitness benefits from helping.

Predation of Eastern Yellow Robin nestlings from the same nest by an Eastern Ringtail Possum and a Pied Currawong

This note describes the predation of nestling Eastern Yellow Robins Eopsaltria australis by an Eastern Ringtail Possum Pseudocheirus peregrinus and by a Pied Currawong Strepera graculina and likely attempted predation by a Red Wattlebird Anthochaera carunculata. Although Eastern Ringtail Possums have been inferred to be predators of birds’ nests, the observations and video presented here appear to be the first unequivocal evidence of carnivory in that species and offer new insights to this possum species’ ecology.

Ambient light energy intensity as a trigger for the dawn chorus: Patterns in five common eastern Australian bird species

The timing of the morning twilight commencement of bird song has been linked to mating, stores of food energy or territorial declarations, and is known to follow a structured, spaced order to avoid signal interference. The timing of vocalisations has been widely studied and varies with ambient and broader environmental variables, including moonlight and cloud cover. In this study, the commencement of morning song for five common species (Masked Lapwing Vanellus miles, Australian King- Parrot Alisterus scapularis, Lewin’s Honeyeater Meliphaga lewinii, Eastern Yellow Robin Eopsaltria australis and Australian Magpie Gymnorhina tibicen) and the relationship with light energy intensity were investigated on the New South Wales Midnorth Coast, eastern Australia. It was determined that each species responded to a specific threshold light intensity as a trigger to commence singing. The timing of song commencement aligned with shifts in the required threshold light level, which was influenced by environmental variables such as moonlight (earlier) and cloudiness (later for some species). It is proposed that the structured routine of the first song of some birds, during nautical twilight, is a result of evolutionary variations in their eye structure, resulting in varying perceptions of the first morning light from the sky, leading to species commencing singing at different times.

A seven‐year study of the response of woodland birds to a large‐scale wildfire and the role of proximity to unburnt habitat

AbstractFire is a major ecological driver in many Australian ecosystems, and large‐scale wildfires can impact on faunal assemblages at a landscape scale. Monitoring the response of the avian community and individual bird species following a 92 039 ha wildfire in the Pilliga Forest, in temperate inland south‐eastern Australia, showed an initial decline in species richness and changes in community composition, followed by gradual recovery. Recovery was not complete by the end of the seven‐year study. Eighteen species (including Speckled Warbler Chthonicola sagittata and Eastern Yellow Robin Eopsaltria australis) were identified as likely to be fire sensitive and nine species (including Australian Magpie Cracticus tibicen and Red‐capped Robin Petroica goodenovii) as likely to respond positively to fire at the time scale of this study. Another 11 species (including Dusky Woodswallow Artamus cyanopterus and Jacky Winter Microeca fascinans) appeared to favour burnt areas close to the fire edge. Guild‐level patterns included an overall negative response to fire by insectivores, granivores/frugivores and declining woodland birds and a positive response by predators. The avian community recovered more quickly at burnt sites close to (within 2 km of) the fire edge compared to more remote sites more than 4 km from unburnt habitat, suggesting that proximity to unburnt areas (and therefore fire extent) is likely to be a key consideration in understanding the post‐fire recovery of birds.

The distribution and frequency of detection of woodland birds after selective logging of a small woodland remnant in an agricultural landscape in inland southern Australia

The majority of studies into the response of birds to logging in Australian forests has been done in forest-dominated landscapes or relatively large forest blocks, where the surrounding landscape can ameliorate impacts. This is the first study to examine the response of birds to logging of a small, relatively isolated woodland remnant in a landscape dominated by agriculture, with a focus on declining woodland birds. Approximately two thirds of a 120 ha cypress-eucalypt woodland remnant was selectively logged. Eighty bird species in total were recorded 2–3½ years after logging, including 18 recognised as declining woodland birds. Sixty-four species were recorded in the unlogged area and 72 in the logged area. Of the 31 species recorded sufficiently frequently for analysis, 19 showed no statistical difference in occurrence between logged and unlogged areas at the power of the study, nine were more prevalent in unlogged areas and three more prevalent in logged areas. Declining woodland birds comprised 22½% of overall species and 33% of those more prevalent in unlogged areas. Mapping of records enabled the response of a subset of species to be examined in greater detail. Four species illustrate the range of responses by declining woodland birds: Eastern Yellow Robin Eopsaltria australis was confined to unlogged areas, White-browed Babbler Pomatostomus superciliosus favoured unlogged areas, Varied Sittella Daphoenositta chrysoptera favoured proximity to unlogged areas and Red-capped Robin Petroica goodenovii was widely distributed in both logged and unlogged areas. The likelihood of recovery of local woodland bird populations is discussed in the context of limited landscape connectivity and the recent colonisation of the remnant by the hyper-aggressive Noisy Miner Manorina melanocephala. White-browed Babbler and Eastern Yellow Robin are considered to be at high risk of local extinction in the remnant.

Estimating the population sizes of rainforest birds of the Tweed Caldera

Climate change is likely to negatively impact populations of rainforest birds along Australia’s eastern seaboard. To this end, accurate estimations of species’ current population sizes are necessary for future monitoring and conservation. Here, we used distance sampling protocols to generate abundance and density estimates for 11 species of birds occupying the Gondwanan rainforests of the Tweed Caldera on the Queensland–New South Wales border. Data were collected along two elevational gradients in subtropical rainforest between September 2015 and October 2016. Half-normal functions with cosine adjustments were used to calculate the density of each species per km 2 . We used a GIS to determine the total area of suitable habitat available in protected areas adjacent to the sampling locations (~425 km 2 ) and then extrapolated the density estimates to generate estimates of population size for each target species in the study area. Estimated population sizes ranged from 473 719 (Yellow-throated Scrubwren Sericornis citreogularis ) to 21 841 (White-throated Treecreeper Cormobates leucophaea ). The standard error (SE) associated with the population estimate of the White-throated Treecreeper was large, as was the SE associated with the Eastern Yellow Robin Eopsaltria australis (estimated population 235 084), Green Catbird Ailuroedus crassirostris (69 731) and Grey Fantail Rhipidura fuliginosa (124 534). Accurate abundance estimates (SE <20% of total abundance) were obtained for the Brown Gerygone Gerygone mouki (193 919), Brown Thornbill Acanthiza pusilla (198 801), Golden Whistler Pachycephala pectoralis (72 730), Lewin’s Honeyeater Meliphaga lewinii (190 389), Silvereye Zosterops lateralis (92 268), White-browed Scrubwren Sericornis frontalis (94 426) and Yellow throated Scrubwren (473 719). Species specific surveys would provide more accurate results, but given the declines expected for many species in the region, and the current lack of estimates of population sizes in these protected areas, the baseline data presented here are of importance from ecological and conservation perspectives.

Perpendicular axes of differentiation generated by mitochondrial introgression.

Differential introgression of mitochondrial vs. nuclear DNA generates discordant patterns of geographic variation and can promote population divergence and speciation. We examined a potential case of mitochondrial introgression leading to two perpendicular axes of differentiation. The Eastern Yellow Robin Eopsaltria australis, a widespread Australian bird, shows a deep mitochondrial split that is perpendicular to north-south nuclear DNA and plumage colour differentiation. We propose a scenario to explain this pattern: (i) first, both nuclear and mitochondrial genomes differentiated in concert during north-south population divergence; (ii) later, their histories disconnected after two mitochondrial introgression events resulting in a deep mitochondrial split perpendicular to the nuclear DNA structure. We explored this scenario by coalescent modelling of ten mitochondrial genes and 400 nuclear DNA loci. Initial mitochondrial and nuclear genome divergences were estimated to have occurred in the early Pleistocene, consistent with the proposed scenario. Subsequent climatic transitions may have driven later mitochondrial introgression. We consider neutral introgression unlikely and instead propose that the evidence is more consistent with adaptive mitochondrial introgression and selection against incompatible mitochondrial-nuclear combinations. This likely generated an axis of coastal-inland mitochondrial differentiation in the face of nuclear gene flow, perpendicular to the initial north-south axis of differentiation (reflected in genomewide nuclear DNA and colour variation).

Skinks and burrowing crayfish as prey items of the Eastern Yellow Robin Eopsaltria australis in south-eastern Australia

This note describes five observations during 2014 and 2015 of predation by Eastern Yellow Robins Eopsaltria australis , on a burrowing crayfish Engaeus sp. and small skinks. This species feeds predominantly on terrestrial invertebrates and insects but these recent observations suggest that it is an opportunistic feeder.

PERCHED AT THE MITO-NUCLEAR CROSSROADS: DIVERGENT MITOCHONDRIAL LINEAGES CORRELATE WITH ENVIRONMENT IN THE FACE OF ONGOING NUCLEAR GENE FLOW IN AN AUSTRALIAN BIRD

Relationships among multilocus genetic variation, geography, and environment can reveal how evolutionary processes affect genomes. We examined the evolution of an Australian bird, the eastern yellow robin Eopsaltria australis, using mitochondrial (mtDNA) and nuclear (nDNA) genetic markers, and bioclimatic variables. In southeastern Australia, two divergent mtDNA lineages occur east and west of the Great Dividing Range, perpendicular to latitudinal nDNA structure. We evaluated alternative scenarios to explain this striking discordance in landscape genetic patterning. Stochastic mtDNA lineage sorting can be rejected because the mtDNA lineages are essentially distinct geographically for > 1500 km. Vicariance is unlikely: the Great Dividing Range is neither a current barrier nor was it at the Last Glacial Maximum according to species distribution modeling; nuclear gene flow inferred from coalescent analysis affirms this. Female philopatry contradicts known female-biased dispersal. Contrasting mtDNA and nDNA demographies indicate their evolutionary histories are decoupled. Distance-based redundancy analysis, in which environmental temperatures explain mtDNA variance above that explained by geographic position and isolation-by-distance, favors a nonneutral explanation for mitochondrial phylogeographic patterning. Thus, observed mito-nuclear discordance accords with environmental selection on a female-linked trait, such as mtDNA, mtDNA-nDNA interactions or genes on W-chromosome, driving mitochondrial divergence in the presence of nuclear gene flow.

Distribution and individual condition reveal a hierarchy of habitat suitability for an area-sensitive passerine

The identification of environmental factors linked to increased risk of local extinction often relies on inference from patterns of distribution. Yet for declining populations, the assumption of population equilibrium that underlies species distribution models is violated. Measures such as individual condition can provide a more direct indication of extinction risk, and can start to be detected before declines commence. We compared distribution-based and condition-based approaches to identifying factors affecting habitat suitability for an area-sensitive passerine, the eastern yellow robin Eopsaltria australis, in eastern Australia. We compared patterns of individual condition between robins and several common, more mobile species (Meliphagid honeyeaters and yellow thornbills Acanthiza nana). Robin presence was not affected by landscape context, but robins avoided sites with a more grassy ground layer. However, robins inhabiting landscapes with less remnant woodland had higher ratios of heterophils to lymphocytes in peripheral blood, indicating higher long-term stress. No clear spatial patterns of condition were detected for the more mobile species. Our findings suggest a hierarchical model of habitat suitability, whereby robins avoid grassy sites, but where they do occur are in poorest condition when inhabiting less-vegetated landscapes. We predict greater rates of local extinction of robins from such landscapes. The use of indicators of individual condition, in addition to distribution data, can unveil otherwise cryptic factors as important influences on habitat quality. As habitat occupancy does not always reflect habitat quality, exploring patterns in condition indices can complement species distribution modelling, potentially revealing threats to persistence before population declines have commenced.

Responses of Eastern Yellow Robins Eopsaltria australis to translocation into vegetation remnants in a fragmented landscape.

Many species of Australian robins (Petroicidae) are declining in wooded landscapes across southern Australia, perhaps because they are unable or unwilling to disperse across the matrix between remnants, or because they experience high mortality while doing so. Eastern Yellow Robins Eopsaltria australis have declined in parts of southeastern Australia, and have gone extinct in some woodland remnants. We translocated adult Yellow Robins to remnants from which they had disappeared, and followed their survival and behaviour. Nine Yellow Robins were translocated to a 100 ha remnant in 2001 (seven birds) and 2002 (two birds). One bird disappeared immediately and a second after 2 weeks, but the rest stayed for at least 2 months, with two birds surviving to at least 4 and 5 years. One reintroduced pair bred each year from 2001 to 2005, producing six fledglings. Two colour-banded Yellow Robins also arrived unaided from another remnant 7 km away. Fifteen Yellow Robins were translocated to nine small remnants (&lt;60 ha) in 2005– 06. Seven birds disappeared within 3 days of their release, apparently killed by predators. The remainder survived for up to 7 weeks, but none was found breeding. Translocated Robins moved up to 3 km from their release sites through natural or planted corridors, and up to 1 km through a matrix of scattered trees. Small remnants, which surviving Robins ultimately vacated, had fewer shrubs than sites where they bred. The results suggest that Eastern Yellow Robins can disperse through a landscape with corridors or scattered trees. However, they may suffer predation and reject sites that are too small or of poor habitat quality. Management to retain Eastern Yellow Robins in a fragmented landscape should enlarge remnants, protect scattered trees, plant or regenerate strategic clumps of trees and shrubs in gaps between remnants, and allow shrubs to regenerate within remnants.

The role of intense nest predation in the decline of Scarlet Robins and Eastern Yellow Robins in remnant woodland near Armidale, New South Wales

A study of open-nesting Eastern Yellow Robins Eopsaltria australis and Scarlet Robins Petroica multicolor, on the New England Tablelands of New South Wales in 2000?02, found low breeding success typical of eucalypt woodland birds. The role of intense nest predation in the loss of birds from woodland fragments was investigated by means of predator-exclusion cages at robin nests, culling of Pied Currawongs Strepera graculina, and monitoring of fledging and recruitment in the robins. Nest-cages significantly improved nest success (86% vs 20%) and fledging rate (1.6 vs 0.3 fledglings per attempt) for both robin species combined (n = 7 caged, 20 uncaged). For both robin species combined, culling of currawongs produced a twofold difference in nest success (33% vs 14%), a higher fledging rate (0.5 vs 0.3 per attempt), and a five-day difference in mean nest survival (18 vs 13 days) (n = 62 nests), although sample sizes for nests in the cull treatment (n = 18) were small and nest predation continued. Although the robin breeding population had not increased one year after the cull, the pool of Yellow Robin recruits in 2001?03, after enhanced fledging success, produced two emigrants to a patch where Yellow Robins had become extinct. Management to assist the conservation of open-nesting woodland birds should address control of currawongs.

Breeding-habitat and nest-site characteristics of Scarlet Robins and Eastern Yellow Robins near Armidale, New South Wales

I studied the selection of breeding habitat and nest microhabitat in Scarlet Robins Petroica multicolor and Eastern Yellow Robins Eopsaltria australis, in remnant woodland on the New England Tablelands of New South Wales in 2000?2002. Yellow Robins used breeding territories (n = 10) with significantly higher densities of rough-barked saplings, acacias and other (non-Acacia) shrubs than Scarlet Robin breeding territories (n = 10) and plots lacking Yellow Robins (n = 7). Yellow Robins nested mostly in gully and lower-slope positions, with a southerly aspect, &gt;40 m from the woodland edge, whereas Scarlet Robins nested mostly on upper slopes and ridges, with no preferred minimum distance from the woodland edge. Most Yellow Robin nests (86% of 58) had overhead foliage within 1 m, shielding them from above, whereas over half (58% of 54) of Scarlet Robin nests were in unconcealed positions. Yellow Robin nests had significantly greater density of cover, and the surrounding habitat was more complex, than for Scarlet Robin nests, in 0.13-ha plots centred on the nest. Breeding success and fledgling survival in the Yellow Robin were positively related to the density of acacias, non-Acacia shrubs and rough-barked saplings (but not gum saplings) in breeding territories. Fledging success and juvenile survival in the Yellow Robin were also positively related to habitat complexity around nest-sites (but not distance to nearest cover, or items of cover within 20 m). Scarlet Robins had exposed nests and suffered high nest predation, with too few successful nests for comparison with unsuccessful nests. Habitat conservation for the Yellow Robin should address the complexity of the ground, shrub and sapling layer in woodland remnants; that for the Scarlet Robin may need to address foraging substrate and ecologically based control of nest predators.

Indicators of habitat quality and the reproductive output of a forest songbird in small and large fragments

The distribution of individuals among habitats that vary in quality (i.e. resource availability) may affect reproductive output at a population level. I compared indicators of habitat quality including the breeding experience ratios (inexperienced:experienced birds), turnover rates, pairing success, and densities of a forest songbird, the Eastern Yellow Robin Eopsaltria australis, in two small, food‐poor forest fragments, with those in two large, food‐rich fragments. I then evaluated the likelihood that the breeding experience ratio affected the reproductive output of populations. Inexperienced males occurred in small fragments eight times as often as in large fragments. Male turnover rates were 1.5 times higher in the small than large fragments, and 20% (10/50) of the male population were unpaired in the small fragments compared to 0% (0/25) in the large. None of these measures differed significantly for females. Experienced birds of both sexes produced almost all of the offspring compared with inexperienced birds. Despite these findings, reproductive output did not vary with fragment size for robins. Thus, while breeding experience clearly influenced the reproductive success of individuals, there were no obvious population consequences of having disproportionately more inexperienced males in the small fragments. I conclude that while male traits may be good indicators of resource levels within fragments (specifically, food availability), they may not be adequate predictors of population performance. Thus, the reproductive output of populations must be measured directly before conclusions concerning population performance can be made. Interestingly, breeding densities were not accurate indicators of either resource levels or population performance. Densities were two times higher in the smaller fragments, and I suggest that this result reflects problems with male dispersal among fragments caused by isolation.

The influence of fragment size and edge on nest predation in urban bushland

To test the effects of habitat fragmentation and edge on the rate of nest predation in an urban ecosystem, 20 artificial nests each containing 2 plasticine eggs were distributed in each of 24 bushland sites in Sydney, Australia. the eastern yellow robin Eopsaltria australis was adopted as a target species, and variables of nests, eggs and nesting behaviour were manipulated in experiments. Sites ranged in size from 3.8 ha to 14717 ha and were divided into three size classes: 1) 0–10 ha. 2) 11–100 ha and 3) ≥101 ha. Nests were positioned either around the edge of the fragment (within 50 m from the fragment boundary) or within the centre of the fragment (&lt; 50 m from the fragment boundary). The predation rate was calculated as the percentage of nests that had one or both eggs damaged or removed after 15 d of exposure. Nest predation rates were high (average 70.6%) but were not affected by patch size or distance from fragment edges. Predators were identified by marks of the beak or teeth left in the plasticine eggs. Nest predators identified were birds, black rats, brown antechinus and ringtail possum, with the majority of predation being by birds (61.7%), Our findings differ from those of most previous studies of nest predation, and perhaps reflect the ubiquity of generalist predators and the degree of habitat modification throughout remnants of bushland in the urban environment.

Responses by birds to fire regime and vegetation at the wet sclerophyll/tropical rainforest boundary

Changes in fire regime have been identified as the cause of the loss of nearly 50% of wet sclerophyll forest in north Queensland in the last 50 years. In the absence of fire, rainforest invades and eventually eliminates the specialized wet sclerophyll forest biota. Bird populations and foraging behaviour were monitored in areas selected to encompass both recent and advanced rainforest invasion. Foraging guilds are discussed in relation to increasing rainforest biomass. Some species, such as the Pale Yellow Robin Tregallasia capito nana were advantaged by the expansion of rainforest. Other species, such as the Golden Whistler Pachycephala pectoralis showed no significant response, whereas the endemic subspecies of the Eastern Yellow Robin Eopsaltria australis magnirostris was clearly disadvantaged. The latter species is of particular concern because in north-east Queensland it is dependent upon wet areas adjacent to rainforest and requires open ground in which to forage. Over the longer term the White-naped Melithreptus lunatus and White-cheeked Phylidonyris nigra Honeyeaters are also threatened by habitat loss. These honeyeaters favour the wetter areas adjacent to the rainforest which are gradually being lost to the invasive process. To maximize biological diversity in the wet tropics of north Queensland, it is necessary to maintain the full spectrum of natural habitats. Fire management is therefore required to maintain the wet sclerophyll forest and its dependent fauna.

The Annual Cycle in a Vocalisation Context: a Comparison of the Eastern Yellow RobinEopsaltria australisand Jacky WinterMicroeca leucophaea

Vocalisation levels and patterns relative to the annual cycle and breeding stages were explored and quantified in two 'typical', double brooded Australian insectivorous passerines, the Eastern Yellow Robin Eopsaltria australis and Jacky Winter Microeca leucophaea. Highest song levels in both occurred in August during the pre-breeding courtship period. They dropped to 10-12%, respectively, towards hatching; rose to 66 and 47% of original levels prior to the second ovulation, then dropped to 21 and 9% of these with the second brood. Levels rose again (markedly in the robin, to minor degree in the Jacky Winter) post-breeding before going into a steady decline with the approach of the moult. A pre-eminent role of song in courtship is thus confirmed for these Australian species. The persistence of some song throughout the year (in the robin) also suggests that song has a continuing role in temtory maintenance in resident Australian species. A basic diel temporal singing pattern (peak song before, or around, sunrise; low levels through the day) characterised all seasons. The pattern was markedly suppressed at times of low seasonal song activity.

Nest-Records of the Eastern Yellow Robin Eopsaltria Australis

Seven hundred and seventy nest-record cards of the Eastern Yellow Robin Eopsaltria australis were available at the end of the 1980-1 breeding season, about one-quarter being from the Moruya district of New South Wales. They provided details but little new information on habitat, nests and nest sites, except that the birds probably nest high in forest trees more often than was supposed. Laying was at intervals of about 27 hours. Clutch size averaged 2.33 without any detectable differences between years, places or altitudes but increasing from 2.16 before to about 2.5 after October. The incubation period was just under 16 days and the nestling period 10-14 days. Breeding success was about 30%, apparently decreasing from 33% before October to about 20% in November and December; the most frequent clutch size (2) was most frequently successful but clutches of three raised more young per nest than did clutches of two. The breeding season started at the end of July or in early August and stopped quite abruptly at the end of December, with the main peak of laying from mid-September to mid-October. More nests were started before 31 August in Victoria than at Moruya. The analysis was dominated and distorted by the quantity and quality of records from Moruya and few useful comparisons could be made between the results from there and from elsewhere.