Competition between the greater bilby and European rabbit at claypans in Currawinya National Park

Levay, Gabriella (2022) Competition between the greater bilby and European rabbit at claypans in Currawinya National Park. Honours thesis, University of Southern Queensland. (Unpublished)

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Greater bilbies (Macrotis lagotis) are a vulnerable marsupial native to Australia. They have numerous threats including competition and habitat destruction from introduced herbivores, habitat loss due to human activities, predation from introduced predators, and increased drought and fires due to climate change. European rabbits (Oryctolagus cuniculus) are considered to significantly impact bilbies through competition for burrows and food resources, as well as through destruction of habitat by overgrazing. However, the most common cause of failure in reintroduction efforts is predation by feral cats (Felis catus) and foxes (Vulpes vulpes), which rabbit presence may support higher numbers of. The Bilby Fence in Currawinya National Park is a ‘predator-proof’ fenced enclosure that bilbies have been released into to create an insurance population with the end goal being a self-sustaining population outside the fence. Claypans inside the Bilby Fence have been identified as being utilised by both bilbies and rabbits. Both bilbies and rabbits dig and occupy burrows underneath swamp paperbark (Melaleuca densispicata), a shrub commonly found around the edges of claypans. They likely use the claypans to forage for food as claypans retain water longer than the surrounding areas, leading to increased food availability. Competition between bilbies and rabbits was investigated at claypans in terms of overlap in activity at shared spaces and diet. This project will fill important gaps in understanding of how much bilbies and rabbits overlap in their diets at the same site during the study period, as well as provide insight into how they may compete or avoid competition by reducing time present in shared spaces. It should be noted that the study was performed during a period of abnormally abundant resources due to excessive rain before the study period; it would be better to conduct this study again in drier conditions more representative of the usual environmental conditions. It was hypothesised that bilbies utilise different areas of the claypans to rabbits to avoid interspecific competition with rabbits. Bilby tracks were present significantly more outside claypans than inside, while there was no significant difference in the number of rabbit tracks inside and outside claypans. There was no significant difference in the number of bilby and rabbit tracks overall, inside or outside claypans, although only five out of 10 transects (two inside and three outside) had both bilby and rabbit tracks present during the study. Based on the camera trap data there was no significant difference between the number of bilby and rabbit events overall, inside claypans, or outside claypans within the Bilby Fence. There was an 81.7% temporal overlap of activity based on the camera trap data. Bilbies were not observed foraging inside claypans but were observed foraging over 50% of the time outside claypans. Rabbits spent marginally more time foraging outside (35.8%) than inside (32.5%) claypans. The Proportional Similarity Index between bilby and rabbit scat contents was 0.25, indicating no dietary overlap. A higher proportion of invertebrates, seeds and sand were found in bilby scats, and a higher proportion of vegetative and fibrous plant material was found in rabbit scats. The hypothesis was not supported as during the study period, there was little overlap in diet to indicate interspecific competition between bilbies and rabbits and there was temporal and spatial overlap of their activities to suggest bilbies were not avoiding rabbits. This is possibly due to a low density of both species and an abundance of resources following plentiful rain before the study was undertaken; there was little dietary overlap and bilbies did not appear use different parts of the claypan to rabbits.

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Item Type: Thesis (Non-Research) (Honours)
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Sciences (6 Sep 2019 - 31 Dec 2021)
Supervisors: Murray, Peter; Allen, Benjamin
Qualification: Bachelor of Science (Honours) (Environment and Sustainability)
Date Deposited: 28 Jun 2023 23:40
Last Modified: 28 Feb 2024 01:47
Uncontrolled Keywords: Activity; Behaviour; Bilby; Bilby Fence; Camera trap; Claypan; Competition; Currawinya National Park; Dietary overlap; Macrotis lagotis; Oryctolagus cuniculus; Predator-proof fence; Rabbit; Semi-arid; Temporal overlap; Tracks
Fields of Research (2020): 31 BIOLOGICAL SCIENCES > 3109 Zoology > 310901 Animal behaviour
31 BIOLOGICAL SCIENCES > 3109 Zoology > 310904 Animal diet and nutrition
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280111 Expanding knowledge in the environmental sciences
18 ENVIRONMENTAL MANAGEMENT > 1806 Terrestrial systems and management > 180601 Assessment and management of terrestrial ecosystems

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