Signaling systems in Australian wild dogs: Who's calling and who cares?
Alarm and distress vocalizations are important anti-predator strategies for many species. An alarm call is a particular vocal response to potential or actual danger, whereas a distress call is an involuntary emotional response to a similar situation and/or stimuli. Alarm and distress calls are often associated with prey species. Australian wild dogs (dingoes, feral dogs and their hybrids) have been observed utilizing similar strategies in response to intense human interactions. We analyzed the spectral (frequency and amplitude shifts) and temporal (call length) components of vocalizations recorded from trapped wild dogs and compared these to vocalizations from captive individuals under non-stressful situations. (i) Vocal responses to trapping are not restricted to distress calls. (ii) The structure of wild dog vocalizations differs across sites, suggesting local dialects or individual differences exist. (iii) Age and social status may affect the type of call elicited by an individual. Understanding the differences in vocalizations of wild dogs in varying environments is vital to the success of remote acoustic monitoring endeavors and to the improvement of wildlife management as a proxy for individual stress. Understanding how vocal communication varies across groups will aid in understanding the evolution of the dingo.
Cautionary considerations for positive dingo management: a response to the Johnson and Ritchie critique of Fleming et al. (2012)
Johnson and Ritchie (2012) have provided a criticism of our opinion piece (Fleming et al. 2012). There is some common ground, but we remain unconvinced by their view that our reasoning was unsound or beside the point. In this response, we discuss where Johnson and Ritchie have provided unconvincing evidence to refute our seven considerations, and reiterate and demonstrate why these considerations remain important. The mesopredator release or suppression hypothesis in Australian ecosystems must be objectively evaluated before positive management of dingoes and other free-ranging dogs is recommended or implemented. Adaptive comanagement of free-ranging dogs can be used for both biodiversity conservation and the mitigation of livestock predation but caution must be exercised when considering using free-ranging dogs as a conservation tool.
Quantifying effects of wild dogs, domestic dogs and humans on the spread of rabies in Australia
Rabies is a preventable viral zoonosis that causes inflammation of the brain, and eventually death, in infected mammals. With few exceptions, including Australia, terrestrial rabies can be found worldwide. More than 55,000 deaths from rabies infection are reported annually; these are mainly in Asia and Africa where the primary reservoir is the domestic dog.
Despite ongoing control efforts in Indonesia, canine rabies remains a disease of critical concern there. Although rabies is not endemic in Australia, at less than 300km away in Indonesia, a rabies incursion is a likely and imminent threat.
To improve preparedness for a canine rabies outbreak in Australia, I collected data on a number of extant dog populations in northern and eastern Australia. I used a range of methods including self-administered questionnaires, GPS telemetry collars, camera trapping and mark-recapture studies. Using my own data and parameters collected from the wider literature, I developed state-transition models to determine how rabies could spread through these dog populations. Finally, I used these same models to evaluate a range of control strategies, including dog removal and vaccination, to identify the most effective options for reducing impacts in Australian communities following a rabies incursion.
Model outputs suggested that rabies will progress differently within functionally different dog populations present within Australia. Restrained domestic dogs posed limited risk for rabies transmission, because interactions with other dogs were limited and generally supervised by owners. Free-roaming domestic and hunting dogs will likely play an important role in rabies transmission in some situations only, primarily based on their ability to roam, access to other free-roaming dogs and their interactions within and between dog groups. Wild dogs (including dingoes) proved the most critical type of dog for rabies spread and maintenance in Australia, because they are widely distributed, often in high abundance, roam over large distances and frequently interact.
I found that time to detection for rabies in wild dogs will likely be lengthy, probably due to low infection rates prior to an epidemic and limited contact with humans, relative to the other categories of dog that I studied. Further, the capacity of authorities to implement effective control strategies for wild dogs will likely be restricted because of limited access to individual animals. The economic costs of controlling a rabies outbreak involving wild dogs will be substantial and likely equivalent to the costs for extensive aerially-based wild dog control that are currently used in some areas of Australia (~Aus$34 km-2).
Australia’s current plans to address rabies incursions, which were developed in the 1990s are clearly outdated. My findings reveal that revision of these plans, taking specific account of relevant differences between restrained domestic dogs, free-roaming domestic dogs and extensive wild dog populations is necessary to ensure that Australia is adequately prepared for the arrival of canine rabies.
Human-resource subsidies alter the dietary preferences of a mammalian top predator
Resource subsidies to opportunistic predators may alter natural predator-prey relationships and, in turn, have implications for how these predators affect co-occurring prey. To explore this idea, we compared the prey available to and eaten by a top canid predator, the Australian dingo ('Canis lupus dingo'), in areas with and without human-provided food. Overall, small mammals formed the majority of dingo prey, followed by reptiles and then invertebrates. Where human-provided food resources were available, dingoes ate them; 17% of their diet comprised kitchen waste from a refuse facility. There was evidence of dietary preference for small mammals in areas where human-provided food was available. In more distant areas, by contrast, reptiles were the primary prey. The level of seasonal switching between small mammals and reptiles was also more pronounced in areas away from human-provided food. This reaffirmed concepts of prey switching but within a short, seasonal time frame. It also confirmed that the diet of dingoes is altered where human-provided food is available. We suggest that the availability of anthropogenic food to this species and other apex predators therefore has the potential to alter trophic cascades.
Homo sapiens is the apex animal: anthropocentrism as a Dionysian sword
Anthropocentrism, where humans are central, is a natural human viewpoint, but a threat to objective ecological study. Human population, resource use and resource expectations are expanding, turning our ecological footprint into a deep rut. We believe that, while many studies deal with the consequences of human effects on ecosystems, the outcomes are viewed as if humans were observers rather than participants in ecosystems. Humans are the apex animal, manipulating most ecosystems with forestry, mining, agriculture, manufacturing and urbanisation: we engineer the landscape, the air, the water and even the climate. In many situations, humans are also the top predator, killing both our competitive mesopredators and their herbivorous prey. Leaving the top predator out of models reduces the alternative hypotheses and imposes directional bias on the responses of subordinate trophic levels. Our objective here is to discuss the roles of the human in the room and the consequences of ignoring them when designing experiments, proposing explanatory models and interpreting studies.
Signalling systems in Australian wild dogs: Who's calling and who cares?
Alarm and distress vocalizations are important anti-predator strategies for many species. Whilst there is some overlap, an alarm call is a particular vocal response to potential or actual danger, whereas a distress call is an involuntary emotional response to a similar situation and/or stimuli. Alarm and distress calls are often associated with prey species; however, Australian wild dogs (dingoes, feral dogs and their hybrids) have been observed utilizing similar strategies in response to intense human interactions. We analyzed the spectral (such as frequency and amplitude shifts) and temporal (such as call length) components of vocalizations recorded from trapped wild dogs and compared these to vocalizations from captive individuals under non-stressful situations. Data collection is on-going but we have early indications that (i) vocal responses to trapping are not restricted to distress calls, (ii) the structure of wild dog vocalizations differs across sites, suggesting local dialects or individual differences exist and (iii) age and social status may affect the type of call elicited by an individual. Understanding the differences in vocalizations of wild dogs in varying environments is vital to the success of remote acoustic monitoring endeavors; and to the improvement of wildlife management as a proxy for individual stress. Finally, understanding how vocal communication varies across these groups will aid in unravelling the evolution of the dingo.
As clear as mud: A critical review of evidence for the ecological roles of Australian dingoes
Top-predators have been reported to have an important role in structuring food webs and maintaining ecological processes for the benefit of biodiversity at lower trophic levels. This is thought to be achieved through their suppressive effects on sympatric mesopredators and prey. Great scientific and public interest surrounds the potential use of top-predators as biodiversity conservation tools, and it can often be difficult to separate what we think we know and what we really know about their ecological utility. Not all the claims made about the ecological roles of top-predators can be substantiated by current evidence. We review the methodology underpinning empirical data on the ecological roles of Australian dingoes ('Canis lupus dingo' and hybrids) to provide a comprehensive and objective benchmark for knowledge of the ecological roles of Australia’s largest terrestrial predator. From a wide variety of methodological flaws, sampling bias, and experimental design constraints inherent to 38 of the 40 field studies we assessed, we demonstrate that there is presently unreliable and inconclusive evidence for dingoes’ role as a biodiversity regulator. We also discuss the widespread (both taxonomically and geographically) and direct negative effects of dingoes to native fauna, and the few robust studies investigating their positive roles. In light of the highly variable and context-specific impacts of dingoes on faunal biodiversity and the inconclusive state of the literature, we strongly caution against the positive management of dingoes in the absence of a supporting evidence-base for such action.