Wallabies and Roads: Interactions and Management in an Urbanising Landscape Author Blacker, Amy Rachael Published 2014 Thesis Type Thesis (PhD Doctorate) School Griffith School of Environment DOI https://doi.org/10.25904/1912/123 Copyright Statement The author owns the copyright in this thesis, unless stated otherwise. Downloaded from http://hdl.handle.net/10072/367128 Griffith Research Online https://research-repository.griffith.edu.au Wallabies and Roads: Interactions and Management in an Urbanising Landscape Amy Rachael Blacker B.Sc. (Hons) Griffith School of Environment Science, Environment, Engineering and Technology Griffith University Submitted in fulfilment of the requirements of the degree of Doctor of Philosophy January 2014 Abstract Understanding the impacts of roads on wildlife and the natural environment is of increasing importance, especially in the context of widespread urbanisation. Macropods (mostly kangaroos and wallabies) are a diverse and widespread taxon in Australia that has been significantly affected by the presence of roads in various ways. Although a moderate volume of research has been conducted on the interactions between macropod species and roads in Australia, this a fraction of the research effort conducted on large mammals in Europe and North America. Research that encompasses a variety of aspects of interactions between roads and macropods (and wildlife in general) is needed to broaden our perspective on impacts and mitigation. Patterns of wallaby road mortality were investigated in a per-urban area of South East Queensland. Wallaby road-kill rates varied greatly; between 0.044 and 0.883 road-kills km-1 month-1 at the road or road section scale. Four wallaby mortality hotspots and several other areas of high mortality density were identified from the kernel density spatial analysis. Percent of commercial vehicle traffic (positively correlated) and distance to water (negatively correlated) were important spatial variables for determining the patterns of red-necked wallaby road-kill. Cumulative rainfall over the previous four weeks and maximum wind gust speed (both negatively correlated) were important temporal variables in determining the patterns of red-necked wallaby road-kill. Too few swamp wallaby road-kills were observed to be analysed. i Wildlife warning signs are a common mitigation measure used to reduce the incidence of wildlife-vehicle collisions, yet there is little evidence of their effectiveness. A public opinion survey was conducted primarily to compare the likelihood of driver response to eight wildlife warning sign designs. There were a total of 134 participants in the survey and three sign designs were ranked highly by participants. Animal-activated and vehicle speed-activated signs (not graphically displayed) were also highly likely to produce a response from drivers. Much more research into optimising the design of wildlife warning signs is needed to maximise driver response and improve the effectiveness of a relatively inexpensive road impact mitigation measure. Little is known of the behaviour of wildlife around roads, yet their behaviour can be a significant contributor to their susceptibility to road mortality. Red-necked wallaby behaviour during road-crossing events (N = 192 adults) and in response to vehicles (N = 166 adults) were investigated. Red-necked wallaby road-crossing behaviour varied greatly among individuals, yet was overall slightly more risky at the road with the highest traffic volume and speed limit. Here more wallabies paused (45%) more frequently (up to 9 times) during crossings and were more likely to emerge directly from the surrounding habitat onto the road without first stopping to assess the traffic condition. Wallabies were more likely to flee from approaching trucks (86% fled), as opposed to smaller vehicles (39% fled), and higher tolerance levels (lower response) to traffic was observed at the road with intermediate traffic volume. The tendency for wallabies to flee from approaching trucks may be a key contributor to their susceptibility to road ii mortality, as the percent of commercial vehicle traffic was identified as a contributing factor to patterns of red-necked wallaby road mortality. The activity budgets of wallabies (N = 186) were affected by the presence of roads. Foraging (mean allocation of time = 39.2-59.6%) and vigilance (mean allocation of time = 30.8-51.1%) were the dominant activities observed. Time allocated to foraging and grooming (mean allocation of time at roads = 2.3-3.0% cf. control = 4.7%) tended to be reduced near roads, with wallabies allocating more time to vigilance and locomotion (mean allocation of time at roads = 2.5-4.1% cf. control = 1.5%) than when they were further away from roads. Variance in time allocated to grooming also tended to be reduced at the road sites, although not significantly so. Vigilance rates were significantly higher near roads than away from roads, potentially increasing stress levels. Again, slightly higher tolerance levels were observed at the road with intermediate traffic volume. This study contributes to the body of knowledge of the interactions between macropods and roads, particularly in peri-urban landscapes. The contribution of commercial vehicles to wallaby, and possibly other wildlife, road mortality may have significant implications for the management of road mortality in some areas and the construction of new roads that are primarily for the transportation of heavy vehicles. This relationship needs to be explored further, as well as the behavioural contribution to road mortality risk. More research needs to be conducted, especially regarding the impact of roads on macropod population dynamics and viability and optimising mitigation measures that are able to be implemented in a wide range of landscapes. As seen with other wildlife species, declines in road-impacted peri-urban populations can occur relatively quickly, and iii thus should be regularly monitored and managed in order to be prevented or at least detected early. iv Statement of Originality This work has not previously been submitted for a degree or diploma in any university. To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made in the thesis itself. Amy Blacker v Table of Contents Abstract..................................................................................................................................................... i Statement of Originality .................................................................................................................... v Table of Contents ................................................................................................................................ vi List of Figures .........................................................................................................................................x List of Tables ........................................................................................................................................ xv List of Appendix Tables ............................................................................................................... xviii Journal articles arising from this thesis ................................................................................... xix Acknowledgements ........................................................................................................................... xx 1. Background and general introduction ............................................................................... 1 1.1. Introduction ............................................................................................................................. 1 1.2. Patterns of macropod road mortality ............................................................................ 5 1.2.1. Traffic volume ............................................................................................................. 7 1.2.2. Local road attributes ................................................................................................ 8 1.2.3. Landscape attributes ..............................................................................................10 1.2.4. Temporal variations ...............................................................................................11 1.2.5. Behavioural responses to vehicles ....................................................................14 1.2.6. Demographic biases................................................................................................15 1.2.7. Human aspects on macropod-vehicle collisions .........................................16 1.3. Movement and behaviour around roads ....................................................................19 1.4. The impact of roads on the viability of macropod populations.........................21 1.5. Road crossing structures and other mitigation devices for macropods and other wildlife ................................................................................................................23 1.5.1. Wildlife warning signs ...........................................................................................24 1.5.2. Road crossing structures and wildlife-exclusion fencing ........................25 vi 1.5.3. Warning reflectors, acoustic repellents and scent repellents ................32 1.6. Research gaps .......................................................................................................................34