The past century has seen a significant rise in the recognition of Indigenous rights to land, leading to formal changes in the way land is governed and managed [1,2]. Much of the land that is owned and managed by Indigenous people is in places with high species richness and ecological intactness compared with more developed, modified and heavily populated areas [3,4]. Further, it is acknowledged that the biodiversity that occurs on Indigenous lands is highly dependent on Indigenous peoples’ knowledge, practices and cultural connections to their traditional estates [5,6]. Despite a history of intermittent conflict with the form of conservation imposed by settler societies [7,8], Indigenous communities frequently manage their land in ways that are not only consistent with biodiversity conservation but often have the explicit purpose of retaining it [9,10]. This provides benefits to broader society, including the protection of native flora and fauna, carbon sequestration and intact waterways [11], and these benefits are linked to human wellbeing [12].

The biodiversity values delivered by Indigenous lands are extremely important, particularly given current unprecedented global declines in species populations and ecosystem integrity [13]. The IUCN now classifies more than 20,000 plants and 57,000 animals as ‘threatened’ worldwide [14], with habitat loss, invasive species, overexploitation, pollution and nutrient loading and climate change identified as the main culprits [15]. The Convention on Biological Diversity (CBD) outlines a set of goals, including a target to prevent extinctions of threatened species and improve and sustain their conservation status (Aichi Target 12) [16]. Signatory nations translate these targets to national level strategies. In Australia, these include a national reserve system strategy (including Indigenous Protected Areas) that systematically conserves representative samples of biodiversity [17] and a national threatened species strategy aimed at halting species declines [18].

The implementation of Australia’s national level strategies requires conservation that transcends land tenure boundaries [19] and can be operationalized under a range of governance and implementation models, including the establishment of new protected areas and supporting community-based conservation on Indigenous land [20,21]. Initiatives that recognise and remunerate maintenance of the ecological values and services delivered from land managed by Indigenous people can serve both to protect nature and enhance the livelihoods of Indigenous people, many of whom are among the most disadvantaged in the world [8]. These initiatives include the establishment of Indigenous Protected Areas [22], Indigenous Community Conservation Areas (http://www.iccaconsortium.org/), and REDD+ and other Payments for Ecosystem Service schemes [23,24], as well as development projects which aim to integrate conservation and development for Indigenous peoples.

Given this context, it is perhaps unsurprising that Indigenous land management is a small but growing sector in many parts of the world [25]. In Australia, for example, there are now over 700 Indigenous land management rangers employed across the continent whose jobs and activities are predominantly financed by the Australian Government with an investment of approximately AU$85m per annum [26].The establishment of schemes to formalise Indigenous land management and the delivery of benefits to broader society have typically occurred based on local capacity, values and funding availability. As yet there is a lack of quantitative spatial understanding of how local-scale Indigenous Land and Sea Management (ILSM) efforts can link to national level strategic planning goals. A more strategic approach could ensure that the benefits of such schemes are maximised, for both Indigenous people and broader society, and that resources are allocated effectively, efficiently and equitably [27,28]. Information on the overlap between areas where and how Indigenous peoples can practice land management and the biodiversity that wider society values is a critical first step in identifying viable options for partnerships that maximise these outcomes.

In this paper we investigate the potential for threatened species management on Indigenous land, using the vast country of Australia as a case study. We use the distributions of threatened native vertebrate species to estimate the relative importance of Indigenous land in Australia for managing threatened species. We analyse overlap in modelled ranges for 272 terrestrial and freshwater wildlife species (includes subspecies) protected under national legislation (for all species and separate taxonomic groups) with the 52% of the Australian land mass to which an ongoing connection by Indigenous people is currently recognised. We investigate bioregional hotspots on Indigenous lands where the ranges of multiple threatened species ranges overlap. We then identify potential areas and pathways for Indigenous people to contribute to national level biodiversity priorities on their land should they choose to do so.

We created a map of Indigenous land across Australia using data from official agencies responsible for the registration of various Indigenous land tenures. These include National Native Title Tribunal, Australian Government Department of Environment and Energy, Indigenous Land Corporation, National Land and Water Resources Audit, and Geoscience Australia. The map represents legally recognised tenure with the type of rights and opportunities conveyed varying with the form of tenure. We categorized the different Indigenous land management pathways according to the rights Indigenous people have over land management under Australian law into those areas where Indigenous people have freehold land tenure and exclusive native title rights (113.59 million hectares Mha), Indigenous people have established co-management partnerships in protected areas (27.36 Mha), and tenure where Indigenous people have negotiated to take part in conservation management as part of a land use agreement (259.75 Mha) (Table 1).

We utilized distribution data of Australian vertebrate fauna (mammals, birds, reptiles, frogs and fish) listed as threatened under the Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act) from the Species of National Environmental Significance Database. These maps are predictive distributions of individual species based on range and suitable habitat. The precision of the data is divided into three classes: 1) Known to occur–areas of preferred habitat near known locations, 2) Likely to occur–areas of preferred habitat within the range of the species, and 3) May occur–areas within a broad environmental envelope or geographic region that encompasses the probable range of the species. In our analyses we only included data from the first two categories. These were amalgamated into a single class.

Species distributions were generalised to a 10km² grid resolution (0.1 degrees). Migratory and marine species were removed as the distributions available may not reflect the total distribution of these species, leaving a total of 272 species for which we have distribution data (80 bird species, 40 fish, 28 frogs, 79 mammals and 45 reptiles). Species were grouped into their scheduled threat status within the EPBC Act List of Threatened Species (Critically Endangered, Endangered, and Vulnerable).

Australia’s terrestrial land area covers approximately 769 Mha, of which 401 Mha (or 52%) is covered by some form of Indigenous tenure (Fig 1). The total area of combined habitat ranges occupied by all 272 threatened species is 735Mha. Of this, 51.3% (376.9Mha) is on Indigenous land, ranging from 57.4% for mammals to 18.1% for fish (Table 1). Almost three quarters, 74.3% (202), of Australian threatened species have at least part of their modelled range on Indigenous land. The percentage of species ranges on Indigenous land for frogs is 85.7%, for mammals 82.3%, and is lowest for fish (57.5%) and reptiles (68.9%) (Table 1). Twenty-two species have more than 75% of their range on Indigenous land (Table 2) including five species with more than 99% of their range on Indigenous land (Amytornis merrotsyi pedleri Gawler Rangers Short-tailed Grasswren, Lasiorhinus krefftii Northern Hairy-nosed Wombat,Mogurnda clivicola Flinders Ranges Mogurnda, Zyzomys maini Arnhem Land Rock Rat and Zyzomys palatalis Carpentarian Rock Rat). At least 31of the 20 birds and 20 mammals listed for special attention under the National Threatened Species Strategy occur on Indigenous lands. Over 70% of the projected range of the Lagorchestes hirsutus Mala, Zyzomys pedunculatus Central Rock Rat, Notomys aquilo Northern Hopping Mouse, Pezoporus occidentalis Night Parrot and Amytornis woodwardi White-throated Grasswren is encompassed within Indigenous lands.

The number of species in any 10km² cell ranged from one to 17. The range for each of the individual species groups was from one to nine for mammals, one to eight for birds, one to five for frogs and reptiles, and one to four for fishes. For all species, apart from reptiles, the coastal areas of Indigenous land contained the greatest number of species (Fig 2). By far the greatest number of overlapping species ranges on the Indigenous land within the 89 bioregions were in South East Queensland (1486 10km² grid cells containing overlapping species ranges, each with a minimum of three and maximum of 17 overlapping species ranges totalling 16534 overlapping species ranges across the bioregion), Southern Coastal Plains (1866 10km² grid cells containing overlapping species ranges, each with a minimum of two and maximum of 14 overlapping species ranges totalling 15691 overlapping species ranges across the bioregion) and Northern Kimberley (2261 10km² grid cells containing overlapping species ranges, each with a minimum of one and maximum of nine overlapping species ranges totalling 12911 overlapping species ranges across the bioregion) (S1 Table).