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Threatened species receive much attention in conservation science and practice. Species currently declining, but not yet listed as threatened, also deserve consideration to reduce their risk of sliding towards extinction and to maintain their functional roles in ecosystems. Information on declining bird species in Australia is available from four main sources: national databases, syntheses of historical change, regional monitoring programmes and summaries for guilds of species. Many species show evidence of decline; declines of species are occurring nation-wide, and they are ongoing. Trends for individual species vary geographically; they may be declining in part of their range but stable elsewhere. Common trajectories of population decline include: (a) a downward linear trend; (b) a marked downturn, sustained at a lower level; and (c) fluctuations through time associated with episodic events (e.g. drought) and incomplete recovery. Ongoing declines affect ecosystems through reduced species richness, homogenisation of bird communities, changes to interspecific interactions and ecosystem services, and contributing to extinction debt. Improving the conservation outlook for declining species requires systematic monitoring to know where, when and how much decline is occurring, together with protection of critical habitats and source populations, ambitious programmes of restoration, and identification and effective control of threats. Responding to declining species offers opportunities for community engagement, monitoring and action at a local and regional level. New ways are needed to incorporate such species in conservation planning and environmental regulation at a regional scale, to give them greater visibility and avoid local declines accumulating until taxa become nationally threatened. Many bird species in Australia, not (yet) listed as threatened, are experiencing population decline and warrant greater attention in conservation planning and management. Patterns of change for individual species vary regionally, depending on past land-use and current pressures. Ongoing decline and loss of species has profound consequences for Australian ecosystems, including depleted and homogenised bird communities and reductions in the diverse ecosystem services that birds provide. New approaches are needed to provide formal recognition and appropriate management for declining species, particularly at a regional level, so they become more visible in environmental planning and can persist in regional landscapes. [ABSTRACT FROM AUTHOR]

Context: The decline of birds in farmland is of global concern. Aims. The aim of this paper was to provide a local-scale case study of the bird fauna of temperate inland eastern Australia's sheep-wheat belt. Methods. Relationships between species occurrence and various habitat elements in the landscape were examined in a 342 km2 area of agricultural countryside near Wagga Wagga in southern inland New South Wales, Australia. The pre-agricultural bird fauna of this area was also investigated by collating records from previous studies of nearby larger woodland remnants. Key results: The study identified a bird fauna of 115 species compared to 160 species known from nearby woodland remnants. Significant relationships were found with the presence of farm dams, extent of local woodland cover and roadside woodland at the levels of individual species, guilds and total fauna. A small ephemeral wetland also contributed substantially to waterbird diversity. Conclusion. Twenty commonly recorded species typical of the farmland matrix and 15 species considered at particular risk of local extinction were identified. At the guild level, frugivore/granivores, small insectivores and hollow-users were found to be associated with remaining woodland elements in the agricultural landscape. Implications. Ecologically sustainable management of agricultural areas is essential to avoid further local extinctions. Hollow-using species are expected to be particularly affected by the anticipated widespread loss of trees in the landscape over the next century. [ABSTRACT FROM AUTHOR]

Simple Summary: We aimed to investigate how an invasive cavity-breeding bird, the common (Indian) myna, and a native nest predator, the common brushtail possum, influence urban nest box use by native birds in Queensland and New South Wales, Australia. We quantified nest box use by invasive and native species, assessed nesting success and failure rates, and explored what environmental factors might influence nest box occupancy and nesting success. We found that the native possums were the most common nest box users and that possum occupancy of boxes was associated with higher rates of nesting failures by all bird species. More common myna nesting attempts were observed in areas where mynas have been established longer. We found no evidence of a significant negative impact by the common myna on other birds in our study locations, which may be partly due to the low rates of use of our nest boxes by native birds. Nevertheless, better nest box design and guidelines for setting them up are needed if we aim to provide more nesting opportunities for native birds to replace the decline in big old cavity trees. Many bird species in Australia require tree hollows for breeding. However, assessing the benefits of urban nest boxes to native birds requires frequent monitoring that allows to assess nesting success. To better understand the benefits of nest boxes for native birds, we examined the impact of local habitat characteristics, invasive species (common myna, Acridotheres tristis), and native mammalian predators on urban nest box use and nesting success of native birds. We installed 216 nest boxes across nine locations in southeastern Australia (S.E. Queensland and northern New South Wales) in both long-invaded sites (invaded before 1970) and more recently invaded sites (after 1990). We monitored all boxes weekly over two breeding seasons. We recorded seven bird species and three mammal species using the nest boxes. Weekly box occupancy by all species averaged 8% of all boxes, with the species most frequently recorded in the nest boxes being the common brushtail possum (Trichosurus vulpecula), a native cavity user and nest predator. We recorded 137 nesting attempts in the boxes across all bird species. The most frequent nesting species were the invasive alien common mynas (72 nesting attempts). We recorded an average nesting failure rate of 53.3% for all bird species. We did not record any common mynas evicting other nesting birds, and found that several native species used the same box after the common myna completed its nesting. We recorded native possums in 92% of the boxes, and possum occupancy of boxes per site was negatively correlated with bird nesting success (p = 0.021). These results suggest that when boxes are accessible to invasive species and native predators, they are unlikely to significantly improve nesting opportunities for native birds. To ensure efficient use of limited conservation resources, nest boxes should be designed to target species of high conservation importance and limit other species of both predators and competitors. [ABSTRACT FROM AUTHOR]

The decline of woodland birds around the world is well known. There are likely to be many causal factors acting together and interacting synergistically, such as habitat fragmentation and the invasion of exotic species. Similarly, insect declines, which likely have been occurring for some time in Australia, have been recorded around the world in recent years, especially in areas of intensive agriculture or urbanisation. Because a large proportion of woodland birds are insectivorous, we ask whether the loss of food resources could also be a driver of bird declines. We encourage more research into this. [ABSTRACT FROM AUTHOR]

Many longitudinal studies of regional avifaunas have been conducted in Australia, but the majority concern temperate inland regions. We examined changes in the avifauna of the Rockhampton region (10 500 km2) in subtropical, coastal Central Queensland, Australia, over 130 years, comparing accounts from 1888, 1925 and 1973–1974 with survey data from 2000 to 2019. Of the 307 confirmed species recorded until 1975, 11 resident species have since disappeared from the region, while another 11 species appear to have declined. This is the highest number of extinct bird species reported to date in a region larger than 1000 km2, although the annual extinction rate is surpassed by that of Coomooboolaroo, a pastoral property of 454 km2 only 100 km away, which lost 18 species over a similar period. Eleven (50%) of the 22 extirpated or declining species forage primarily on the ground, and 12 (55%) are primarily insectivorous. Eucalypt woodland is the major habitat of 11 species (50%), while another five (23%) are associated with rainforests. Species loss and decline coincided with habitat loss: 63% of the eucalypt woodland and 70% of the rainforest have been cleared since Europeans settled in the region. Livestock overgrazing probably played a role in the extirpation of four species of finches. The decline of at least 11 species since 1975 coincided with three consecutive decades of low rainfall, and an ongoing increase in ambient temperature. Of the 307 confirmed bird species recorded in the Rockhampton region of Australia between 1887 and 1975, 11 species have disappeared, most likely due mainly to clearing of eucalypt woodland and rainforest, and overgrazing. This is the highest number of extirpated species reported for an area of greater than 1000 km2 in Australia to date. [ABSTRACT FROM AUTHOR]

Aim: The distribution and abundance of forest biodiversity can be shaped by multiple drivers, including disturbances like wildfires. We quantified the influence of wildfire severity and bird life history attributes on temporal patterns of bird site occupancy. Location: Wet eucalypt forests of Victoria, Australia. Methods: We employed a Before, After, Control, Impact experimental design, gathering occupancy data on birds 5 years before, and for 10 years after, a wildfire in 2009. We quantified post‐fire decline and then recovery on sites subject to high‐severity fire, comparing these temporal patterns with those for birds at sites that were unburnt or burnt at moderate severity. We also tested the influence of life history attributes on bird responses to wildfire. Data were analysed using joint species distribution modelling, accounting for imperfect detection. Results: We found a two‐way interaction between fire severity and time period for overall bird site occupancy. The largest change between time periods was on sites burnt at high severity where bird occupancy declined immediately after fire followed by a strong recovery. Occupancy patterns remained largely unchanged on unburnt sites. For many individual species, interactions between fire severity and time period were similar to overall species occupancy. On sites subject to high‐severity fire, most species recovered to pre‐fire levels within 6 years. We found no evidence of a three‐way interaction between fire severity, time period, and life history attributes, with all trait groups of birds examined largely recovered to pre‐fire site occupancy levels 10 years post‐fire. Main conclusions: The Victorian 2009 wildfires were severe, but their impacts on common bird species were relatively short‐lived, with immediate post‐fire declines mostly reversed within ~10 years. Rapid post‐fire stand regeneration appears a likely driver of these responses and may account for the relatively limited influence of life history attributes on bird species recovery. However, diet influenced bird species occupancy after fire, with nectivores recovering slower than insectivores on sites subject to high severity fire. Our findings may be relevant to other forests types globally where there can be rapid post‐fire vegetation growth and stand regeneration. [ABSTRACT FROM AUTHOR]

Across Australia’s Wet Tropics region, populations of rainforest-dependent birds have declined because of climate change. Reforestation and regenerating secondary forest on abandoned agricultural land may help bolster species’ populations by expanding and connecting habitat. However, little is known about the value of these habitats for rainforest birds, or the impacts of climate change on secondary forests and their fauna compared with primary forests. At a 62-ha, mid-elevation property with primarily secondary forest cover on the Atherton Tablelands, in the Wet Tropics region, Queensland, we examined changes in bird species reporting rates on weekly lists between 2000–2005 and 2014–2019. Reporting rates of grassland and eucalypt-forest species decreased as expected because the area of ungrazed pasture was reduced over time, while the area occupied by tree plantings and naturally regenerating forest increased and matured. Reporting rates of most mixed-forest (61%) and nearly half (47%) of rainforest-dependent bird species also decreased significantly between the two time periods, despite the quality of rainforest habitat improving at the site. We infer that climate change is the cause of these declines. Five of the rainforest-dependent bird species whose reporting rates decreased in this study are known to have moderately increased in abundance in mid-elevation primary forest. Hotter, drier secondary forests may not be as well buffered as primary forest from the impacts of climate change, reducing their suitability as habitat for many bird species such as these. However, further studies are needed in secondary forests to investigate this. [ABSTRACT FROM AUTHOR]

Anguillid eel populations have declined dramatically over the last 50 years in many regions of the world, and numerous species are now under threat. A critical life-history phase is migration from freshwater to distant oceans, culminating in a single life-time spawning event. For many anguillids, especially those in the southern hemisphere, mystery still shrouds their oceanic spawning migrations. We investigated the oceanic spawning migrations of the Australasian short-finned eel (Anguilla australis) using pop-up satellite archival tags. Eels were collected from river estuaries (38° S, 142° E) in south-eastern temperate Australia. In 2019, 16 eels were tracked for up to about 5 months, ~ 2620 km from release, and as far north as the tropical Coral Sea (22° S, 155° E) off the north-east coast of Australia. Eels from southern Australia appeared to access deep water off the Australian coast via two main routes: (i) directly east via Bass Strait, or (ii) south-east around Tasmania, which is the shortest route to deep water. Tagged eels exhibited strong diel vertical migrations, alternating between the warm euphotic zone (~ 100–300 m, 15–20 °C) at night and the mesopelagic zone (~ 700–900 m, 6–8 °C) during the day. Marine predators, probably lamnid sharks, tuna, or marine mammals, ended many eel migrations (at least ~ 30%), largely before the eels had left the Australian continental shelf. The long and risky marine migrations of Australasian eels highlight the need for better information on the processes contributing to eel mortality throughout the life cycle, including the impacts of future changes to oceanic currents, predator abundance and direct anthropogenic disturbances. [ABSTRACT FROM AUTHOR]

Fire 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. [ABSTRACT FROM AUTHOR]

Many migratory birds are declining worldwide. In line with the general causes for the global biodiversity crisis, habitat loss, pollution, hunting, over‐exploitation and climate change are thought to be at the basis of these population declines. Long‐distance migrants seem especially vulnerable to rapid anthropogenic change, yet, the rate of decline across populations and species varies greatly within flyways. We hypothesize that differences in migration strategy, and notably stopover‐site use, may be at the basis of these variations in resilience to global change.By identifying and comparing the migration strategies of two very closely related shorebird species, the Curlew sandpiper Calidris ferruginea and the Red‐necked stint Calidris ruficollis, migrating from the same non‐breeding site in Australia to similar breeding sites in the high Russian Arctic, we aimed to explain why these two species express differential resilience to rapid changes within their flyway resulting in different population trajectories in recent times.Based on 13 Curlew sandpiper and 16 Red‐necked stint tracks from light‐level geolocator tags, we found that individual Curlew sandpipers make use of fewer stopover areas along the flyway compared to Red‐necked stints. Furthermore, and notably during northward migration, Curlew sandpipers have a higher dependency on fewer sites, both in terms of the percentage of individuals visiting key stopover sites and the relative time spent at those sites. While Curlew sandpipers rely mainly on the Yellow Sea region, which has recently experienced a sharp decline in suitable habitat, Red‐necked stints make use of additional sites and spread their relative time en‐route across sites more evenly.Our results indicate that differential migration strategies may explain why Curlew sandpipers within the East Asian‐Australasian Flyway are declining rapidly (9.5%–5.5% per year) while Red‐necked stints remain relatively stable (−3.1%–0%). We consider that more generally, the number of sites per individual and among a population, the spatial distribution across the flyway, as well as the relationship between the time spent over sites may prove to be key variables explaining populations and species' differential resilience to environmental change. [ABSTRACT FROM AUTHOR]

Background: Globally, amphibian species have suffered drastic population declines over the past 40 years. Hundreds of species are now listed as Critically Endangered, with many of these considered “possibly extinct”. Most of these species are stream-dwelling frogs inhabiting remote, montane areas, where remnant populations are hard to find using traditional surveys. Environmental DNA (eDNA) could revolutionize surveys for ‘missing’ and endangered amphibian populations by screening water samples from downstream sections to assess presence in the upstream catchments. However, the utility of this survey technique is dependent on quantifying downstream detection probability and distances. Methods: Here we tested downstream detection distances in two endangered stream frogs (Litoria lorica and L. nannotis) that co-occur in a remote stream catchment in north-east Australia, and for which we know precise downstream distributional limits from traditional surveys. Importantly, the two last populations of L. lorica persist in this catchment: one small (~1,000 frogs) and one very small (~100 frogs). We conducted eDNA screening at a series of sites kilometers downstream from the populations using precipitation from two fixed water volumes (15 and 100 mL) and via water filtering (mean 1,480 L). Results: We detected L. nannotis and the small L. lorica population (~1,000 frogs) at most sampling sites, including 22.8 km downstream. The filtration method was highly effective for far-downstream detection, as was precipitation from 100 mL water samples, which also resulted in consistent detections at the far-downstream sites (including to 22.8 km). In contrast, we had limited downstream detection success for the very small L. lorica population (~100 frogs). Discussion: The ecological aspects of our study system, coupled with thorough traditional surveys, enabled us to measure downstream eDNA detection distances with accuracy. We demonstrate that eDNA from a small population of approximately 1,000 frogs can be detected as far as 22.8 km downstream from the population. Water filtration is considered best for eDNA detection of rare aquatic species—indeed it was effective in this study—but we also achieved far-downstream detections when precipitating eDNA from 100 mL water samples. Collecting small water volumes for subsequent precipitation in the lab is more practical than filtration when surveying remote areas. Our downstream detection distances (>20 km) suggest eDNA is a valuable tool for detecting rare stream amphibians. We provide recommendations on optimal survey methods. [ABSTRACT FROM AUTHOR]

Woodland birds are a species assemblage of conservation concern, and their persistence in fragmented agricultural landscapes is dependent on both the preservation of existing woodland remnants and the implementation of restoration plantings. However, little is known about the habitat‐use and persistence of birds in fragmented agricultural landscapes. We present a detailed, population‐oriented study of woodland birds in temperate eucalypt woodland restoration plantings and remnant woodland patches in the South‐west Slopes bioregion of New South Wales, Australia. First, we undertook a 3‐yr mark–recapture project to assess annual survival and site fidelity in restoration plantings and woodland remnants. We supplemented our recapture efforts with resightings of color‐banded individuals. Second, we tracked individual birds of two species, Superb Fairywren (Malurus cyaneus) and Willie Wagtail (Rhipidura leucophrys), and documented snapshots of their home ranges and movement patterns during the breeding season. Annual survival in the woodland bird assemblage was lower than expected (51%). Home ranges of the Superb Fairywren were positively correlated with patch size, and were constrained by patch edges in linear sites. Superb Fairywrens and Willie Wagtails were more likely to travel longer distances between substrates while foraging in linear sites. Willie Wagtails engaged in significant gap‐crossing (up to 400 m) between adjacent habitat patches. Our findings indicate that (1) patch isolation and certain patch configurations place resident birds at an energetic disadvantage, and (2) in our study area, woodland bird populations are continuing to decline. We recommend landscape‐scale habitat restoration programs aim to address ongoing population declines. Studies such as ours conducted over longer time periods would provide a deeper understanding of habitat use and population processes of woodland birds in fragmented agricultural landscapes. [ABSTRACT FROM AUTHOR]

Threatened species that exist in small isolated populations are vulnerable to extinction processes, so effectively monitoring the trajectory of such populations will help determine the most appropriate management actions to combat extinction threats. In this study, we aimed to track the population status of the fossorial heath skink Liopholis multiscutata that is listed as threatened in Victoria, south‐eastern Australia, and exists there as a few small and highly disjunct populations, by using an appropriate surrogate population monitoring metric. This secretive lizard is a habitat specialist, is highly localised in Victoria and lives in warrens in semi‐arid heathland or mallee on large dunes. Survey data, which included every warren and their constituent burrows, as well as an assessment of whether each burrow was 'active', were collected for the four known Victorian populations in 2007 and annually during 2014–2018 inclusive. We compared five population indices per monitoring site: number of active warrens (NAW), number of active burrows (NAB), population area for 80% of active warrens (PA80), percentage of warrens that were active (PAW) and average number of active burrows per active warren. The heath skink currently occurs in small populations (8–46 active warrens) and these populations have typically declined over recent years. NAW was the most robust metric; NAB and PA80 did not reveal strong temporal trends. PAW indicated that inactive warrens and burrows persist less than a year and hence may provide information about recent (within months) population changes. It is imperative to establish a material link between the effective monitoring of small, vulnerable populations and the implementation of management actions that benefit such populations. Here, NAW could be used as a long‐term monitoring tool to provide an estimate of the minimum population size of the heath skink at a site. Its use would also ensure continuity in monitoring approaches for the Victorian populations. [ABSTRACT FROM AUTHOR]

The Pied Imperial-Pigeon (Ducula bicolor) is a summer migrant to northern Australia, and nests colonially on many islands of the Great Barrier Reef, Queensland. Numbers are perceived to have declined as a result of large-scale shooting in the past and clearing of their mainland feeding grounds. To obtain evidence of any population changes, 1–10 counts were made each breeding season of the evening flight from the mainland to a nesting colony on North Brook Island. The counts began in 1965 and have continued for 50 years. The count represents one individual of a pair that visits the mainland to feed and returns in the evening. In the 1965–66 breeding season, the December count (the count used to compare years) was 4692 birds. Over the following three seasons, numbers declined to a low of 1451 birds in 1968–69; this decline was attributed to shooting of up to 1100 birds at a time. Large-scale shooting stopped in 1968 and was followed by a steady exponential increase (y = 3370.4e0.0908x in numbers over 23 years to 29 818 birds in the 1992–93 season. Numbers have fluctuated between ∼25 000 and 35 000 individuals over the following 18 years. A tropical cyclone of extreme intensity affected the pigeons' breeding site on North Brook Island and their mainland feeding areas in February 2011. In the following breeding season of 2011–12, numbers fell to 5311, but recovered to 21 088 in the 2012–13 season. The dramatic drop in numbers was attributed to the pigeons moving elsewhere for the 2011–12 season. It is predicted that the post-cyclonic number of 21 088 will take 4 years to recover to 30 000. The counts are a simple and somewhat coarse measure of population trends, but provide a population baseline for more sophisticated studies on the movements of pigeons and their responses to long-term changes in habitat and climate. [ABSTRACT FROM AUTHOR]

The article discusses a study which examines the declines of the bird species White-throated Needletails Hirundapus caudacutus in Australia. Analysis at various sites in Victoria between 1960s and 2011-2012 detected significant population declines as well as in the whole country since 1950s. The causes and reasons for the declines are also investigated.

Anthropogenic environmental change is driving the rapid loss of biodiversity. Large declines in the abundance of historically common species are now emerging as a major concern. Identifying declining populations through long‐term biodiversity monitoring is vital for implementing timely conservation measures. It is, therefore, critical to evaluate the likelihood that persistent long‐term population trends of a given size could be detected using existing monitoring data and methods. Here, we test the power to detect declines in Australia's common landbirds using long‐term citizen science monitoring. We use spatially explicit simulations of occupancy dynamics and virtual sampling, designed to mimic bird monitoring in better‐sampled regions of Australia, to assess likely power in these data to detect trends relevant for conservation. We predict the statistical power for 326 common species that meet minimum requirements for monitoring data across 10 regions of Australia, estimating the number of species for which we would have a high (≥80%) chance of detecting declines of different sizes. The power to detect declines of ≥30% per decade was predicted to be high for at least one‐third of the common species in 7 of 10 regions, with a total of 103 (32% of 326) unique species sufficiently monitored in at least one region. These species spanned 12 taxonomic orders, four orders of magnitude in body mass, and a broad diversity of dietary guilds, suggesting the current species pool will likely serve as robust indicators for a broad range of environmental states and pressures. Power was strongly affected by species' detectability, and power to detect even large declines was negligible when species are detected on ≤50% of visits to an occupied site. Predicted power for many species fell just short of the 80% threshold in one or more regions, which suggests an increase in effort targeting these species could greatly enhance the species and regional representation of these data. Against the backdrop of unprecedented biodiversity losses, this study shows how critical evaluation of existing monitoring schemes is valuable both for assessing the contribution of citizen science schemes to biodiversity monitoring and for designing strategic monitoring to significantly improve the knowledge these schemes provide. [ABSTRACT FROM AUTHOR]