Publications

Addressing Threats and Ecosystem Intactness to Enable Action for Extinct in the Wild Species

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Type: Journal Article

Reference: Dalrymple, S.E., Abeli, T., Ewen, J.G., Gilbert, T.C., Hogg, C.J., Lloyd, N.A., Moehrenschlager, A., Rodríguez, J.P., & Smith, D. (2023). Addressing Threats and Ecosystem Intactness to Enable Action for Extinct in the Wild Species. Diversity 15, 268. doi.org/10.3390/d15020268

Abstract

The species listed as Extinct in the Wild (EW) in the IUCN Red List of Threatened Species consist of 84 plants and animals that have been lost from their indigenous range. EW species are therefore restricted to ex situ conservation facilities and often have populations founded with few individuals. Our analysis demonstrates that 60% of EW species are associated with ecoregions that have very low proportions of intact habitat. Furthermore, threats such as invasive species, pollution, and climate change affect just over half of EW species and compound the obstacles facing their reinstatement to the wild. Despite these bleak assessments, there are various options for EW recovery. We present five scenarios that encapsulate the circumstances facing EW species and suggest potential conservation action for each of these situations. We illustrate these scenarios using case studies of EW species that demonstrate how the various options of ex situ management, reintroduction, and assisted colonisation to new habitat can be used to address the very exacting requirements of EW species. Our aim is to present a broad review of the obstacles facing the recovery of EW species whilst inspiring action to prevent the extinction of the most imperilled species on the planet.

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Reproductive skew in a Vulnerable bird favors breeders that monopolize nest cavities

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Type: Journal Article

Reference: Stojanovic, D., McLennan, E., Olah, G., Cobden, M., Heinsohn, R., Manning, A. D., Alves, F., Hogg, C. & Rayner, L. (2023). Reproductive skew in a Vulnerable bird favors breeders that monopolize nest cavities. Animal Conservation. doi: 10.1111/acv.12855

Abstract

Reproductive skew occurs when a few individuals monopolize breeding output, which can act as a mechanism of natural selection. However, when population sizes become small, reproductive skew can depress effective population size and worsen inbreeding. Identifying the cause of reproductive skew is important for mitigating its effect on conservation of small populations. We hypothesized that superb parrots Polytelis swainsonii, which strongly select for the morphology of tree cavity nests, may be reproductively skewed toward pairs that monopolize access to nests. We use SNP genotyping to reconstruct a pedigree, estimate molecular relatedness and genetic diversity of wild superb parrot in the Australian Capital Territory. We successfully genotyped 181 nestlings (a census between 2015–2019) and showed they were the progeny of 34 monogamous breeding pairs. There was a strong reproductive skew – 21 pairs bred only once producing 40% of the nestlings, whereas 13 pairs bred two to four times, producing 60% of the total nestlings. Five of these repeat-breeders produced 28% of all nestlings, which was nearly triple the productivity of one-time breeders. Repeat breeders usually monopolized access to their nest cavities, but the few pairs that switched nests did not differ in fecundity from those that stayed. The cause of nest switching was unknown, but uninterrupted access to a suitable nest (not minor variations in morphology between nests) better predicted fitness of breeding superb parrots. Pedigrees offer powerful insights into demographic processes, and identifying reproductive skew early provides opportunities to proactively avoid irreversible loss of genetic diversity via conservation management. We identify new research questions based on our results to clarify the relationship between access to resources and breeding success.

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Assisted Colonisation as a Conservation Tool: Tasmanian Devils and Maria Island

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Type: Book Chapter

Reference: Hogg, C., & Wise, P. (2022). Assisted Colonisation as a Conservation Tool: Tasmanian Devils and Maria Island. In M. Gaywood, J. Ewen, P. Hollingsworth, & A. Moehrenschlager (Eds.), Conservation Translocations (Ecology, Biodiversity and Conservation, pp. 476-483). Cambridge: Cambridge University Press. doi:10.1017/9781108638142.029

Summary

Tasmanian devils are endangered due to an infectious clonal cancer that has reduced populations by up to 80 per cent since it first arose in 1996. As part of a management strategy for the species, an island population was established through an assisted colonisation event on Maria Island
National Park. The original scope of the Maria Island population was to establish and maintain a disease-free population of devils. The island is now used as a source site for these trial releases of devils to mainland Tasmania populations. The 2012 release cohort to the island had a high degree of relatedness. However, through dedicated management strategies, including contraception and selective harvesting, this situation has been rectified and the Maria Island population now represents a genetically diverse group. Monitoring, using traditional methods of trapping and camera traps, in addition to genetic monitoring, has been essential to the establishment and maintenance of the Maria
Island population.

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