Developing global vulnerabilities and conservation priorities for cave-dwelling bats

Abstract

Research and conservation interventions are disproportionately focused on taxa perceived as charismatic, while other systems with high levels of endemism, and often under-protected such as caves and subterranean ecosystems remain neglected. Bats are keystone to cave ecosystems making them ideal surrogates to understand diversity patterns and assay conservation priorities. Using a novel framework, we assessed and mapped the global bat cave vulnerabilities and priorities at the biome and site level. Almost half (N = 678, 48%) of bat species across the world regularly use caves, with 32% endemic to a single country, and 15% currently threatened with extinction. Tropical realms and small-ranged species faced the highest levels of risk. Our analyses consistently showed that most caves with lower threat levels show higher cave biotic potential (i.e., evolutionary distinctiveness and endemism), though this may be due to the loss of species from more disturbed caves. We estimate that 3% to 28% are high-priority caves for conservation in broad-scale (biome level) and fine-scale (site-dependent) analyses respectively. Amongst regions, the highest concentration of conservation priority areas are in the Palearctic and tropical regions (except Afrotropical), which requires more intensive data sampling. Our results further highlight the importance of prioritising bat caves at local scales but show that broader scale analysis is possible if robust cave data is present and effective parameters are included (i.e., appropriate landscape features and threats). Developing priorities for these systems requires more systematic approaches as a standard measure to develop the priorities needed to maintain cave diversity.

DarkCideS 1.0, a global database for bats in karsts and caves

“…The DarkCideS database was initially conceptualised and developed by KCT, JAG, and ACH as part of the "Global Bat Cave Vulnerability and Conservation Mapping Initiative" in 2014, and later with the "Mapping Karst Biodiversity in Yunnan" and the "Southeast Asian Atlas of Biodiversity" projects. The initiative includes developing tools and methods (e.g., the Bat Cave Vulnerability Index 20 ) and synthesis (e.g., the global bat cave vulnerability assessment 17 ) to identify conservation priorities and important bat caves in the tropics. Since 2019, the initiative has expanded and potential collaborators and contributors were invited through scientific conferences (Association for Tropical Biology and Conservation 2018, International Bat Research Conference 2019), social media platforms, and personal correspondences.…”

“…The third dataset included in the database contains the measured land-use and landscape features of the cave surroundings using the georeferenced data from the second dataset (Table 3, Figure 4). The selected landscape features measurements of the 2002 cave sites were selected based on Tanalgo et al 17 . We included the estimated distance and measures of twelve (N = 12) landscape variables in the database including canopy cover height 29 , tree density 30 , distance to bodies of water 31 bare ground cover change 32 , short vegetation cover change 32 , tall tree cover change 32 ; for vulnerabilities we included distance to urban areas 32 , distance to roads 33 , mine density 34 , night light 35 , relative pesticide exposure 36 , and population density 37,38 .…”

“…For example, we have multiple datasets from the Palearctic, Indomalayan, and Neotropical realms, whereas very little data originated from the Afrotropical region (Figure 3). We also encountered similar coverage bias in country-level data richness, for example, Indonesia is one of the most diverse countries for estimated cave-dwelling bat species richness 17 , but a very small number of species were included in the current version of the database. The database is intended as a long-term data-sharing platform, and we hope to fill these gaps in the next versions of the database.…”

“…Bats are keystone species in karst ecosystems and ideal cave conservation surrogates, delivering vital energy sources into caves as they regularly forage from outside ecosystems. Cave ecosystems are critical for bats, with around half of all bat species reliant on caves, with a high rate of endemism and proportion of threatened species facing high risks from varying threats 17 . Nevertheless, conservation attention towards cave-dwelling bats remains limited compared to other mammalian taxa.…”