Trends and lessons from thirty years of Australian threatened bird action plans

KEYWORDS:

• IUCN Red List
• recovery planning
• monitoring
• science history
• extinction

International concern for declining bird species figured prominently in the formation of many ornithological, conservation and scientific organisations across the globe in the late 19^th Century, including the Royal Australasian Ornithologists Union (now BirdLife Australia; Robin 2001). However, despite concerns about the rarity of some species being expressed repeatedly in the early years of the Union (e.g. Ashby 1924), little action was taken to prevent extinctions. As a consequence, it was only in the late 20^th century that the first systematic attempt was made to document which Australian bird species were most threatened with extinction (Brouwer and Garnett 1990).

Shortly after this documentation, the Australian Federal Government passed the first national legislation targeting threatened species, the Endangered Species Act 1992. The government also funded the first action plans for Australian threatened species, including the first Action Plan for Australian Birds (Garnett 1992). This plan had two important consequences. First, it created a foundation of information on the extinction risk of Australian birds on which later assessments could build. Secondly, the Plan established the ultrataxon (monotypic species or subspecies of polytypic species; Schodde and Mason 1999), as the basic unit for Australian bird conservation action. Continued support from the Australian government and the ornithological community has since enabled three other Action Plans to be written at intervals of about 10 years (Garnett and Crowley 2000; Garnett et al. 2011; Garnett and Baker 2021). Each has improved on its predecessor, incorporating new knowledge and insights and expanding the range of sources of information.

It is on these four Action Plans and the data that underpins them that the current special issue of Emu – Austral Ornithology builds. These repeated reviews reveal trends not only in extinction risk to Australian birds but also about the threats they face, the extent of our knowledge and management and the directions Australian threatened bird conservation may go in the future.

The review of Australian avian extinctions (Woinarski et al. 2024) confirms that Australian birds continue to follow the global pattern of gradual declines over the last 100 years and demonstrates that the aims of that first Action Plan were not achieved in their entirety. For example, three taxa (Mount Lofty Ranges Spotted Quail-thrush Cinclosoma punctatum anachoreta, White-chested White-eye Zosterops albogularis and Southern Star Finch Neochmia ruficauda ruficauda) are known to have persisted until after 1992 but were extinct by 2010. One other taxon, the Tiwi Hooded Robin Melanodryas cucullata melvillensis (Woinarski et al. 2021), was also last seen in the 1990s and may now be extinct. Just as with mammals (Woinarski et al. 2015), the number of extinct bird taxa has increased steadily and relentlessly for nearly 250 years. Also, while Australia’s extinct bird taxa have tended to be larger than the overall average and from islands (Olah et al. 2024), most recent extinctions have been of smaller, mainland taxa. Nor is the list of extinctions likely to be complete. Along with the Tiwi Hooded Robin, the Cape Range Rufous Grasswren Amytornis striatus parvus is Critically Endangered (Possibly Extinct) (Black et al. 2021) and even the most recent Action Plan (Garnett and Baker 2021) may have been overly optimistic about the Buff-breasted Buttonquail Turnix olivii (Webster et al. 2021) and Coxen’s Fig-Parrot Cyclopsitta coxeni (Gynther et al. 2021); neither of these latter two species have been reliably sighted for many decades (Garnett et al. 2022; Webster et al. 2022).

For both birds and mammals, however, there would certainly have been more Australian extinctions over the last 50 years had there not been sustained federally coordinated national conservation action. Only one Australian bird species is thought likely to have gone extinct since 1993 had there not been conservation interventions – the Orange-bellied Parrot Neophema chrysogaster (Bolam et al. 2021), which has only been kept from extinction through persistent interventions over many decades (Stojanovic and Heinsohn 2023). Conservation interventions since 1960 have almost certainly saved both the Lord Howe Woodhen Hypotaenidia sylvestris (Frith 2013) and the Noisy Scrub-bird Atrichornis clamosus (Burbidge et al. 2018). At the subspecies level, there are at least six examples for which extinction was prevented – Australian Gould’s Petrel Pterodroma l. leucoptera (Priddel and Carlile 2009), Norfolk Island Morepork Ninox novaeseelandiae undulata (Olsen 1996), Norfolk Island Green Parrot Cyanoramphus novaezelandiae cookii (Ortiz-Catedral et al. 2018), Western Ground Parrot Pezoporus wallicus flaviventris (Burbidge et al. 2018), Helmeted Honeyeater Lichenostomus melanops cassidix (Harley et al. 2018) and probably the Heath Western Whipbird Psophodes n. nigrogularis (Burbidge et al. 2018). For the Norfolk Island Green Parrot, interventions have prevented extinction twice, first from 1987 to the early 2000s when nest boxes were erected and protected from predation and second since 2014, after a period when active management was neglected (Ortiz-Catedral et al. 2018). In the most recent case, intensive predator management has been so successful that nest protection is no longer necessary (Gautschi et al. 2023).

One of the keys to understanding population trends in threatened species is long term, consistent and widespread monitoring (Lindenmayer et al. 2012). However, as Verdon et al. (2024) shows, there has been zero monitoring for 25% of Australian imperilled bird taxa. Such few data are available for these taxa that their extinction risk has had to be inferred from intermittent and incomplete information. For at least some of these taxa, the IUCN Red List category of Data Deficient could potentially be applied, as their assignment to a specific extinction risk category had lower levels of certainty than desirable. However, analysis of the financial investment in conservation from 1990 to 2000 showed that taxa in the Data Deficient category received less funding than equivalent listed taxa (Garnett et al. 2003). This situation led to application of an explicit policy in the Action Plans of 2010 and 2020 to provide an extinction risk category even when data were scarce, while acknowledging the uncertainty (Garnett et al. 2011; Garnett and Baker 2021).

Nevertheless, both the range of taxa monitored and the quality of monitoring has increased over the last 30 years (Verdon et al. 2024). However, the quality of monitoring efforts still needs improvement. Very rarely does long-term monitoring go beyond documenting individual occurrence and locations. This means that declining population trends, once identified, cannot readily be explained. Additionally, within Australia, conservation research on the basic demography of many avian species has only started after declines have been detected and the populations are already compromised. A good example is a suite of avian taxa from Australia’s wet tropics rainforest. Assiduous monitoring of 1770 sites over 17 years from 2000 to 2016 revealed declines in the abundance of many rainforest bird taxa (Williams et al. 2021). These declines align alarmingly closely with the predictions from climate models (Williams et al. 2003) and have been attributed to changes in primary productivity resulting from increases in average temperature and oscillations in rainfall (de la Fuente et al. 2023). However, the basic natural history of many of these bird taxa is so insufficient that the mechanisms underlying these trends remain unclear. Before active management of declining avian populations can be implemented, there is a dire need for basic studies of the natural history of remote threatened and declining populations (Tewksbury et al. 2014).

Climate change is just one of the threats on which research is urgent if extinctions are to be avoided (Garnett et al. 2024b). However, for most Australian threatened bird taxa affected by climate change, there has been little research on how to manage the threat and even less application of that knowledge, even though the management options for many taxa have been known for at least a decade (Garnett et al. 2013; Garnett and Franklin 2014). One of the important benefits from having a longitudinal time-series dataset on threatened bird taxa is that it is possible to detect gradual changes. For example, when the first Action Plan was written in the early 1990s, evidence was emerging for the first time that long-line fishing was killing an excessive number of albatrosses (Brothers 1991). Over the following two decades concerted efforts at multiple scales, which included creation of the multinational Agreement on the Conservation of Albatrosses and Petrels (Cooper et al. 2006) and the Australian bycatch threat abatement plan (Commonwealth of Australia 2018), has led to substantial improvements in managing the threat and reductions in losses (Reid et al. 2023).

In contrast to seabirds, no migratory shorebirds were considered imperilled in the first two Action Plans (Garnett 1992; Garnett and Crowley 2000). By 2010, however, 16 shorebird taxa were listed (Garnett et al. 2011), following analyses of the data collected by hundreds of amateur observers of shorebirds around Australia (Hansen et al. 2018) and creation of the East Asian Australasian Flyway Partnership in 2006 (Murray and Fuller 2012). On the basis of research identifying loss of habitat on the margins of the Yellow Sea as the major reason for decline (Murray et al. 2014, 2018; Studds et al. 2017), partners have been working together to halt the loss of habitat along the flyway. Thus, although the 2020 Action Plan listed 17 migratory shorebird taxa as threatened (Garnett and Baker 2021), there are now signs that the conservation interventions are starting to have a positive impact (Rogers et al. 2023).

Broad trends in extinction risk are best revealed by the Red List Index (RLI) (Berryman et al. 2024), which quantifies changes in extinction risk (Butchart et al. 2007) and this index is increasingly being used to assess conservation performance (CBD 2022). For the period 1990 to 2010, the RLI for Australian bird ultrataxa was much higher (i.e. better) than for bird species globally (Szabo et al. 2012), but Berryman et al. (2024) show that the score for Australian birds has plummeted in the last decade, driven partly by the direct effects of climate change and partly as a consequence of the catastrophic fires of 2019–2020 (Legge et al. 2022, 2023). However, some bird groups have fared better than others. For example, the RLI for mangrove birds, which are predicted to be little affected by climate change in the next 30 years (Garnett and Franklin 2014), has remained at the highest possible score for the last three decades.

There was also a notable rise in the RLI for seabirds, largely driven by a single intensive intervention on Macquarie Island in 2011 (Springer 2016). Removal of the last introduced mammals from the island resulted in the reversal of the population trends for nine bird taxa, with six taxa meeting the criteria for Least Concern by 2015 (Garnett and Baker 2021). The Macquarie Island bird taxa also made up 36% of the bird taxa for which the extinction risk was lower in at least one of the decades from 1990 to 2020 (Garnett et al. 2024a). Apart from the Macquarie Island birds, however, attempts to identify the cause of the reduction in extinction risk across Australian birds have largely failed. Most reductions in extinction risk in Australian birds are specific to the species or location, and not all were the result of conservation interventions.

However, while reasons for reduced extinction risk are elusive, it may be possible to predict which taxa are most likely to have an increased extinction risk in the future. Comparative phylogenetic models have been successful in revealing the most important biological traits that predispose Australian taxa to being imperilled, when compared to non-threatened species (Olah et al. 2024). As elsewhere in the world (Matthews et al. 2022), and with extinct taxa, island endemics in Australia are at greater risk of extinction. So too are taxa with few close relatives and those intolerant of agricultural habitats (Olah et al. 2024).

Being able to predict which taxa are likely to become threatened based on intrinsic biological characteristics is only one facet of conservation. Equally important is understanding the impediments to threat alleviation for threatened bird species (Crates et al. 2024). This much broader question reflects the milieu within which conservation management operates, where there is often a need to balance the requirements of species against the resources available (Joseph et al. 2009). It also underpins the arguments for using cost–benefit analyses to guide conservation investments (McDonald et al. 2015). However, as noted by Gillespie et al. (2020) in the analysis of frog conservation in Australia, cost is only one of a suite of possible barriers; many threats cannot be ameliorated by money alone. For some there is social resistance to change – for example, Baudin’s Black-Cockatoo Zanda baudinii causes substantial losses to orchardists in south-western Australia (Chapman 2007), making it difficult to stop illegal shooting. For other threats, the political will does not necessarily reflect that of the general populace, because of legislative capture by advocacy groups. While, in a democracy, the political will of the majority may eventually lead to policy change (e.g. the shift in Australian climate change policy after sustained public pressure; McAllister 2023), politics can obstruct conservation more than social pressures until democratic turnover improves alignment between society and policy. Technical challenges can also impede progress, meaning further research is needed before threats can be ameliorated. Another factor is simply time. For example, a loss of hollows for nesting by widespread threatened species may take many decades to remedy at a landscape scale (Gibbons et al. 2000). Understanding the feasibility of reducing the impact of threats to Australian threatened birds (Crates et al. 2024) can help guide investment into different types of action that will help reduce extinction risk. For example, there are major technical impediments to helping individual bird taxa respond to climate change (Garnett and Franklin 2014). Invasive species control, in contrast, is often highly feasible and has positive social support (Zander et al. 2022). Control of many invasive species now simply requires money to implement well-known protocols.

Funding is also required to support the management of Country by First Peoples, a facet of conservation where Australia leads the world (Coffey et al. 2023). However, while the Australian population is broadly supportive of the Indigenous ranger programme (Zander and Garnett 2011), Lilleyman et al. (2024) makes the case that support for this management should be seen as natural justice. They point out that threats facing Australia’s birds are almost universally a consequence of colonisation. Therefore, the funding for threat management on First Peoples’ Country, currently far lower than the amount, already inadequate (Craigie and Pressey 2022), provided for protected areas, should be considered a right not a privilege.

To date, First Peoples’ involvement in threatened bird conservation is still far lower than for mammals (Southwell et al. 2023). Lilleyman et al. (2024) shows where benefit for threatened bird conservation could arise from successful collaboration with First Peoples. A key point, however, which is made repeatedly by First Peoples who are managing Country, is that the motives for involvement in conservation often emerge from a world view that may differ from many of those wishing to conserve threatened species (Campion et al. 2023). Partnerships, therefore, need to recognise the holistic nature of land management and respect the legitimacy of First Peoples’ ways of knowing (Fernández-Llamazares et al. 2021; Molnár et al. 2023).

Almost by definition, threatened species make up a tiny fraction of the overall biomass of bird species, so that whatever ecological function they once performed is now much diminished. In contrast, abundant species can still help shape the ecosystems of which they are part, even if their numbers are declining (Baker et al. 2019). The final paper in this Special Issue concerns these many Australian bird taxa that do not meet the IUCN Red list criteria for being at imminent risk of extinction but are nevertheless declining (Bennett et al. 2024). The paper points to one of the hazards of assessing threatened species trends at the scale of a country the size of Australia. The emphasis on national policies to conserve threatened species can reduce the pressure to retain populations at a local level. Bennett et al. (2024) point to variation in population trends across the country, with declines in population size, and sometimes species losses, from many regions even though extinction risk of a taxon remains low. To a small extent this was offset by the early policy decision to use ultrataxon as the unit for threatened bird conservation. Species such as Hooded Robin, Brown Treecreeper or Red-tailed Black-Cockatoo remain abundant, but their threatened subspecies are valued by society no less than are whole species (Garnett et al. 2018) and serve as ambassadors for local sustainable land management. Conservation of taxa threatened at the scale of local governments or First Peoples’ Country may be more appropriate if avian function is to be retained and restored (Garnett 2020).

Conclusion

The pressures on Australian avian biodiversity are enormous and increasing (Legge et al. 2023) and there is a powerful need to shift biodiversity conservation from being a desirable outcome of policy to a fundamental objective (Coffey et al. 2023). Too many Australian bird taxa are already extinct (Woinarski et al. 2024) but much has been achieved since the first Action Plan was published in 1992. While the picture of threatened bird conservation over the last 30 years that emerges from the analyses in this special issue provides many reasons for concern, there are also reasons for hope. There have been substantial improvements in the amount and quality of monitoring (Verdon et al. 2024) and in the understanding and management of threats (Garnett et al. 2024b). As a result, the Red List Index for Australian birds, though showing a grim and declining trend, has some brighter elements (Berryman et al. 2024). At the core of this hope are the small number of bird taxa for which the risk of extinction has declined (Garnett et al. 2024a). We also have a much better idea of which types of bird are likely to be threatened (Olah et al. 2024) and the types of impediments we need to overcome if we are to manage each threat (Crates et al. 2024).

One of the more fundamental changes to conservation over the last 30 years is the respect given to First Peoples, their knowledge, and the extent to which their involvement with threatened bird conservation is supported (Lilleyman et al. 2024). Many Australians probably think of themselves as belonging to a country that includes an entire continent. The hundreds of First Peoples belong to Country at a far finer scale (Bishop et al. 2012). This awareness of the importance of local values underpins an increasing appreciation that reducing extinction risk must be part of a wider movement that transforms the relationship between the Australian population and the environment. In that respect, trends in Australia’s bird species, including the many species that are still abundant, but which are declining either locally or across the nation, are as important to the long-term future of Australia as a civilised society, as are trends for those whose populations are now much diminished (Bennett et al. 2024).

Disclosure statement

No potential conflict of interest was reported by the author(s).