Draft:Conservation of ghost bats

• Comment: Mostly a lot of info that can be part of the species page Bluethricecreamman (talk) 05:12, 2 December 2024 (UTC)

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Ghost bat, Featherdale Wildlife Park, Sydney

Overview

The ghost bat (Macroderma gigas), sometimes referred to as the Australian false vampire bat is a megadermatid bat species native to Australia. While fossil and guano evidence demonstrate an expanded historical range of the ghost bat over a large area of Western Australia ranging deep towards its southern region, modern populations are limited to fragmented regions in the northwest.. The ghost bat is currently classed as Vulnerable by the IUCN Red List.

Historic Range

Fossil Analysis

The range of the ghost bat has historically reached as far south as the very southwestern tip of the Australian continent, as evidenced by Holocene fossil analysis. However, populations are hypothesized to have expanded and contracted in large waves throughout both the Pleistocene and Holocene as a result of large-scale climatic changes throughout the epochs.

Modern Range

The modern range of the ghost bat

The modern range of Macroderma gigas has been greatly reduced from historic ranges and has now been estimated by numerous researchers to be below 10,000 individuals, with an estimated drop of an additional 10% in the next three generations of bats. The modern population is limited to the Pilbara and Kimberley regions of Western Australia, and is largely fragmented throughout those regions.

Modern Threats

Mining and Drilling

Australia has a deep and storied history of mining for materials such as iron, gold, and lead. Abandoned mines in the Pilbara region have become a large focus of recent mining efforts, with modern developments focused on the re-examination of old mines in order to find missed or underutilized ore deposits, particularly gold. Since their abandonment, however, these mines have become prime roosting areas for many of Australia's bat species as a result of the uniquely warm, moist, and dark regions they provide. While studies into modern drilling near roosting sites of M. gigas have been limited and have thus far suggested that drilling further than 85 meters from roosting location would have negligible effects on the population, more research is required to examine the interaction between drilling and further stressors that could intermix to pose significant disruption to existing populations.

Invasive Species

While the introduction of invasive species into an environment often has extremely damaging, unpredictable, and long-term effects, the carnivorous niche that the ghost bat falls into is unique enough to not overlap with surrounding species of bats. However, the cane toad, invasive to Australia, has a range overlapping with that of the ghost bat and has been predated on by it. Being the only Australian bat that predates on native toads, along with recent evidence of the abandonment of historic roosting sites that have been successfully colonised by cane toads, recent research has suggested that the invasion of cane toads may have a significant negative impact on ghost bat populations in the region. Evidence to the support this hypothesis is varied, and widely falls into two main categories:

1. Investigation of ghost bat remains has revealed that predation on cane toads does occur and suggests that the species is susceptible to the bufotoxin produced by cane toads, despite the other 5 species within Megadermatidae being seemingly unaffected by toad toxins.
2. Habitat overlap and range patterns of the cane toad and ghost bats demonstrate correlation, with abandoned historical roosting sites being more moist and thus more susceptible to invasion by the cane toad, and drier sites less habitable to the cane toad remaining inhabited by ghost bats. However, the decline in ghost bat populations has been slower than those of other predators impacted by cane toads, suggesting that it is possible that the cane toad has not been the principal cause of M. gigas decline.

In addition to the cane toad, feral cats in the region represent a significant threat not just to the ghost bat but to worldwide biodiversity at all trophic levels.

Habitat Loss

While drilling near existing roosts has been shown to have lesser impact than originally hypothesized, the largest threat of extirpation specific to the Pilbara region has been the aforementioned increase in mining. Because mines provide a uniquely suited roost for the microclimate most beneficial to the ghost bat , the re-opening of mines in the region has represented an enormous reduction in usable habitat for the species.

Conservation

Reintroduction and Assisted Migration

Significant study has been performed regarding the potential for re-introduction of the species into abandoned historical roosts, along with the translocation of bats between colonies to further the genetic resilience of disjoint populations.

After a 2023 analysis of environmental factors at Drovers Cave National Park showed an extraordinary capacity to act as a thermal buffer with both ample prey for the ghost bat and the ability to limit the expansion to the cane toad (due to limitations of the toad's ability to survive in climates colder than 20°C), a management plan was developed and published in 2024 detailing a strategy for the reintroduction of ghost bats to the region.

Combating Invasive Species

The DCCEEW, Australia's federal environmental regulatory body, currently has multiple programs in place to research both impact of the cane toad and feral cats on the ecosystem and how their impacts and ranges can be mitigated.

Per the DCCEEW's 2015 threat abatement plan for feral cats, over 5 million dollars of federal funding has been allocated to both reducing current populations (via baiting, trapping, and other eradication methods) and isolating current populations (largely via island relocation and exclusion fencing)

The eradication of cane toad populations in Australia has been largely ineffective, and the current focus of conservation lies in managing the interactions between cane toads and invasive species and increasing the ability of native species to survive invasion by cane toads.