Island meltdown: Demise of the Abrolhos painted button-quail Turnix varius scintillans in the face of multiple threats
Date of Award
Edith Cowan University
Master of Science by Research
School of Science
Robert A. Davis
Cheryl A. Lohr
Allan H. Burbidge
Island avifauna suffer high rates of extinction and decline. The major threats to island birds centre around the ecological impacts of invasive predators, competitors, and grazers. The Abrolhos Painted Button-quail (Turnix varius scintillans) is a subspecies that has been determined to be the 5th most likely taxon to become extinct in Australia. T. v. scintillans historically inhabited three islands in the Houtman Abrolhos archipelago off the mid-west coast of Australia. This study aimed to 1) confirm the status of T. v. scintillans on North Island and determine the main causes of decline, 2) model habitat variables with detections from camera traps to identify drivers of habitat use, and 3) identify, if any, spatio-temporal patterns of habitat use.
The last bird recorded on North Island was in 2006. Vegetation declines on North Island due to introduced Tammar Wallabies (Notamacropus eugenii derbianus) and predation by introduced House Mice (Mus musculus) were implicated as major threats. Between 2018 and 2021, 12,820 camera trap-nights on North Island failed to detect any signs of T. v. scintillans, suggesting local extinction. Introduced wallabies and mice combined with reduced rainfall have likely resulted in degradation of habitat critical for T. v. scintillans, which is now confined to just two islands. Preventing further introductions of mice, rats and feral cats is a high priority for limiting further declines of this subspecies.
I measured habitat parameters and modelled them against camera trap detections of T. v. scintillans to determine potential drivers of habitat use. I identified a strong positive correlation between detections of T. v. scintillans and the presence of Bush Rats on West Wallabi island. I found sandy substrates to be positively correlated with detections and limestone pavement sites to be negatively correlated, though both substrates were used by T. v. scintillans. No negative associations were identified between detections of T. v. scintillans and detections of other fauna species. In addition to spatial patterns, I used metadata from camera trap images to show shifts in habitat use from limestone to sand through the day, and spatial and temporal overlap with the ecologically similar Brush Bronzewing (Phaps elegans).
The key findings of this thesis demonstrate the impacts of invasive species on terrestrial, island birds and endorse the utility of camera traps as an ecological research tool, particularly for large-scale surveys on logistically difficult-to-access locations such as remote islands. These findings are applicable to the management of terrestrial biodiversity assets in the recently declared Houtman Abrolhos Islands National Park.
Access to this thesis is embargoed until 10th July 2024
Carter, R. (2023). Island meltdown: Demise of the Abrolhos painted button-quail Turnix varius scintillans in the face of multiple threats. Edith Cowan University. http://dx.doi.org/10.25958/2m4m-kf95