An updated description of the Australian dingo (Canis dingo Meyer, 1793)

A sound understanding of the taxonomy of threatened species is essential for setting conservation priorities and the development of management strategies. Hybridization is a threat to species conservation because it compromises the integrity of unique evolutionary lineages and can impair the ability of conservation managers to identify threatened taxa and achieve conservation targets. Australia’s largest land predator, the dingo Canis dingo, is a controversial taxon that is threatened by hybridization. Since their arrival <5000 yBP (years Before Present) dingoes have been subject to isolation, leading to them becoming a unique canid. However, the dingo’s taxonomic status is clouded by hybridization with modern domesticated dogs and confusion about how to distinguish ‘pure’ dingoes from dingo-dog hybrids. Confusion exists because there is no description or series of original specimens against which the identities of putative hybrid and ‘pure’ dingoes can be assessed. Current methods to classify dingoes have poor discriminatory abilities because natural variation within dingoes is poorly understood, and it is unknown if hybridization may have altered the genome of post- 19th century reference specimens. Here we provide a description of the dingo based on pre-20th century specimens that are unlikely to have been influenced by hybridization. The dingo differs from the domestic dog by relatively larger palatal width, relatively longer rostrum, relatively shorter skull height and relatively wider top ridge of skull. A sample of 19th century dingo skins we examined suggests that there was considerable variability in the colour of dingoes and included various combinations of yellow, white, ginger and darker variations from tan to black. Although it remains difficult to provide consistent and clear diagnostic features, our study places morphological limits on what can be considered a dingo

Lethal control of an apex predator has unintended cascading effects on forest mammal assemblages

Disruption to species-interaction networks caused by irruptions of herbivores and mesopredators following extirpation of apex predators is a global driver of ecosystem reorganization and biodiversity loss. Most studies of apex predators' ecological roles focus on effects arising from their interactions with herbivores or mesopredators in isolation, but rarely consider how the effects of herbivores and mesopredators interact. Here, we provide evidence that multiple cascade pathways induced by lethal control of an apex predator, the dingo, drive unintended shifts in forest ecosystem structure. We compared mammal assemblages and understorey structure at seven sites in southern Australia. Each site comprised an area where dingoes were poisoned and an area without control. The effects of dingo control on mammals scaled with body size. Activity of herbivorous macropods, arboreal mammals and a mesopredator, the red fox, were greater, but understorey vegetation sparser and abundances of small mammals lower, where dingoes were controlled. Structural equation modelling suggested that both predation by foxes and depletion of understorey vegetation by macropods were related to small mammal decline at poisoned sites. Our study suggests that apex predators' suppressive effects on herbivores and mesopredators occur simultaneously and should be considered in tandem in order to appreciate the extent of apex predators' indirect effects

Response to Allen ‘An alternative hypothesis to the conclusion of Colman et al. (2014)’

We respond to the criticisms of Allen regarding Colman et al., examining the differences in forest mammal assemblages between areas where dingoes were controlled and not controlled in southeastern Australia. Allen contends that Colman et al. did not show any evidence of dingo control in 'Treatment' sites; the positive relationship between dingo activity and small mammal abundance observed by Colman et al. was likely a product of bottom-up responses, and not due to indirect effects of dingo removal; and demonstrating trophic cascades resulting from top-predator control is only possible through manipulative experiments. In our response, we explain why we disagree with each of Allen's criticisms

Temporal variation in a savanna bird assemblage : what changes over 5 years?

Tropical savanna environments are characterised by annual and decadal patterns of resource change, which can affect the patterning of mobile fauna such as birds. In this study, we sampled 60 sites in northern Queensland, four times from 2004 to 2008. We investigated how the bird richness and abundance, and species turnover changed over the sample years and how this differed with vegetation structure. The mean abundance per site was highest in 2005 (92.1±12.0 individuals ha-1) and lowest in 2008 (46.6±3.3), whereas species richness per site was highest in 2004 (19.6±0.9 species ha-1) and lowest again in 2008 (14.7±0.8). Nine species were most abundant in 2004 coincident with extremely high rainfall preceding the survey in that year. Species turnover increased across all sites from 2004 to 2008 and the abundance of 13 species was best accounted for by differences in vegetation structure. Our study demonstrates that local bird communities in the semi-arid fringe of savannas can change rapidly, and mostly where vegetation is modified. This suggests that increased land-use and climate change in northern Australia could have significant effects on the avifauna over fairly short periods

A bird survey method for Australian tropical savannas

The tropical savanna of northern Australia is extensive and relatively homogenous compared to the open woodlands of temperate Australia. The avifauna of this biome is unevenly dispersed in the landscape. A standard count method for birds using a timed search along a 100-m transect with eight repeated counts per site over 4 days, has been used extensively over the past decade or more in these savannas, but its effectiveness has never been critically examined. We used data collected from across northern Queensland from 2004 to 2010, comprising 502 single-survey sites (each transect counted eight times) and 60 sites re-sampled four times from 2004 to 2008, to examine species records and accumulation of species over time with respect to time of day, increasing number of repeat counts(from 2 to 32 counts), species turnover, vegetation density effects and distance to first observation. Over 70% of the species in tropical savannas were easily observed and for 93% of the species vegetation structure did not alter detectability. Richness and abundance did not vary significantly across the day. We found that repeated sampling over multiple days, and at different times of the day, provides the best estimate of species richness at a site, and improved detectability