Potential for spillover predation on native fauna by dingoes in peri-urban and agricultural landscapes in Australia's lowland Wet Tropics

Morrant, Damian Stuart (2015) Potential for spillover predation on native fauna by dingoes in peri-urban and agricultural landscapes in Australia's lowland Wet Tropics. PhD thesis, James Cook University.

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Abstract

The lowlands of the Wet Tropics Bioregion (LWT) in north-eastern Queensland, Australia (situated between 18°37' S and 146°09' E, and 16°48'S and 145°41'E) is home to a broad range of threatened and/or endemic fauna species. Dingoes, Canis dingo, in the lowland Wet Tropics (LWT) are perceived to pose a threat to biodiversity conservation because of their predation on species listed as Vulnerable, Endangered, or Critically Endangered under the Nature Conservation Act 1992 (QLD) or Environment Protection and Biodiversity Conservation Act 1999 (Cth) (threatened fauna). These threats are likely to be greatest in periurban areas where dingoes may be subsidised by anthropogenic food resources, enabling them to reach relatively high population densities and thus exert significant predation pressure on threatened fauna.

I investigated three main aspects to determine whether dingoes actually pose a threat to biodiversity conservation in the LWT, and whether public perceptions and attitudes match ecological reality: 1) dingo movement ecology; 2) dingo prey use; and 3) public perceptions and attitudes towards dingoes. My working hypothesis was that, although dingoes may be perceived to pose a threat to fauna populations in the LWT, their patterns of activity, land use and prey selection are more likely to lead them to prey on abundant, generalist mammals rather than on threatened fauna.

I investigated dingo movement patterns in the LWT by GPS tracking nine dingoes to determine whether their temporal and spatial activity patterns suggested that they are likely to interact with threatened fauna, or whether an abundance of anthropogenic food subsidies increases the risk of spillover predation. I generated home ranges using five estimators, two of which have been used by past researchers to quantify dingo home ranges, and three which more-effectively capitalise on the high fix rates possible with modern GPS telemetry. I used two methods to determine the location of rest areas. Subsequent data were analysed using Compositional Analysis of habitat use, and Generalised Additive Models to establish the ways in which dingoes partition their diel activity patterns among human-modified and natural habitats. The results enabled me to make predictions about habitat use, potential prey types, relative prey use, modes of prey acquisition, and the ways in which foraging strategies might respond to changes in prey density. Mean home ranges were similar to those estimated by other studies for dingoes in eastern Australia, and suggest that dingoes in the LWT do not rely on anthropogenic food subsidies. Dingoes were active throughout the day and night but were most active during daylight. When dingoes were most active they were more likely to be in open, disturbed habitats than other habitat types, and when resting they were more likely to be in relatively-dry forests and woodlands, particularly wet sclerophyll. Rainforest was rarely used. It seems that dingoes rest in forested areas, possibly to avoid persecution by humans, and periodically move into open habitats (primarily sugarcane) to hunt. These observations match past suggestions that dingoes, as pursuit predators, are best suited to hunting in open habitats.

I identified the diet of dingoes in the LWT and the potential threat posed to native fauna by using an established predation-risk assessment for threatened fauna, analysing scats and stomach contents, and generating Bayesian stable isotope mixing models using isotope values from the hair of dingoes and potential prey. The predation-risk assessment identified three ground-dwelling bird species that are likely to be threatened by dingo predation. An additional bird species, the estuarine crocodile, and six marine turtles were assessed separately, as their life history characteristics made them unsuitable for the risk assessment. These species may also be threatened by dingoes, and most are known to be susceptible to dingo and dog depredation. However, diet analysis did not identify any threatened species, and the primary prey of dingoes in the LWT was common, open-dwelling mammals. Separate Bayesian mixing models were generated using isotopic values from dingo hair, and four prey groups (agile wallabies; northern brown bandicoots & canefield rats; two melomys species; and green ringtail possums), and three habitat categories (primarily C3 vegetation – 'forest'; primarily C4 vegetation – 'open', and mixed C3 and C4 – 'mixed'). The models support the results of dietary analyses and identified that the most likely set of prey came from 'open' and 'mixed' habitats; 'forest' habitats were not an important source of prey.

I gauged the knowledge and perceptions of WT residents toward the economic, social and ecological costs and benefits of dingoes, free-roaming domestic dogs and dingo × dog hybrids (wild dogs) in general, and their attitudes toward dingoes in particular, via a survey of WT households. A sub-component of this investigation focussed on costs and benefits to native fauna. An attitude typology was developed, and analysed using Principal Component Analysis and Generalised Linear Mixed Models. Descriptive statistics were generated from questions about wild-dog, dingo/human conflict, and public knowledge and perceptions of. Most WT residents believed that 'wild dogs' were a problem and were supportive of a number of methods of managing wild dogs There was strong support for a suite of potential management options for controlling free-roaming domestic dogs and limiting hybridisation, including desexing of domestic dogs in areas where there are wild dog problems, increased powers for council officers to penalise pet owners who allow their animals to roam unrestrained, and fitting pig dogs with tracking collars to allow relocation by their owners should they escape. Respondents perceived a range of costs of wild dogs but their primary concerns were predation livestock and threatened fauna, and disease transmission. However, almost one third of respondents believed that wild dogs provide social, economic, and/or environmental benefits, and the most-commonly cited benefit related to the dingo's role as a trophic regulator. Men and cattle farmers generally held the most negative attitudes toward dingoes; however, cattle farmers showed a strong desire to learn about them.

I synthesised the results of my data chapters to determine whether dingoes actually pose a threat to threatened fauna and whether public perceptions and attitudes toward dingoes match ecological reality. My results suggest that dingoes in the LWT hunt abundant mammals in open habitats and are generally unlikely encounter threatened taxa. Thus, rather than posing a threat to native fauna populations, dingo predatory behaviour may represent an important ecological service. If dingoes do pose a threat to biodiversity conservation in the region it is likely to be in natural areas where remnant vegetation provides habitat for rare and threatened species; however, current dingo management practices tend to focus on areas where dingoes come into conflict with humans, primarily on agricultural holdings.

However, some members of the public perceive that dingoes pose a threat to native fauna. The attitudes and beliefs of the public drive management decisions, and it is important that public perception of wildlife is informed by tangible evidence. Given the knowledge gaps in relation to the trophic effects of the dingo, and the potential implications of such knowledge gaps for biodiversity conservation, management decisions relating to dingoes in the LWT must be based on scientific evidence rather than anecdote. Management should focus on maintaining stable dingo packs in areas where they may be beneficial, unless shown to be otherwise, whilst concurrently aiming to quantify their impacts at targeted sites in natural habitats where they may not be.

Item ID: 41168
Item Type: Thesis (PhD)
Keywords: agricultural pests; animal tracking; biodiversity conservation; Canis dingo; dingo; dingoes; endangered species; food; forest and woodlands fauna; habitats; home ranges; invasive species ecology; lowland Wet Tropics; movement ecology; perceptions; pest control; pests; predation risk assessment; predators; Queensland; terrestrial ecology; Wet Tropics; wild dogs
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Publications arising from this thesis are available from the Related URLs field. The publications are:

Butler, James R.A., Linnell, John D.C., Morrant, Damian, Athreya, Vidya, Lescureux, Nicholas, and McKeown, Adam (2014) Dog eat dog, cat eat dog: social-ecological dimensions of dog predation by wild carnivores. In: Gompper, Matthew E., (ed.) Free-Ranging Dogs and Wildlife Conservation. Oxford University Press, Oxford, UK, pp. 117-143.

Date Deposited: 02 Dec 2015 00:13
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060208 Terrestrial Ecology @ 34%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050103 Invasive Species Ecology @ 33%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 33%
SEO Codes: 96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960403 Control of Animal Pests, Diseases and Exotic Species in Farmland, Arable Cropland and Permanent Cropland @ 34%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 33%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960505 Ecosystem Assessment and Management of Forest and Woodlands Environments @ 33%
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