Tag Archives: trophic interactions

The case for a dingo reintroduction in Australia remains strong: a reply to Morgan et al., 2016

Authors: Thomas M Newsome, Aaron C Greenville, Mike Letnic, Euan G Ritchie and Christopher R Dickman

Published in: Food Webs (early view)

dingofootprint

We challenge the arguments of Morgan et al. in regard to the efficacy of dingo reintroductions Image credit: Daryll Bellingham via Flickr

In their paper “Trophic cascades and dingoes in Australia: does the Yellowstone wolf-elk- willow model apply?” Morgan et al. (2016) argue that the case for dingo reintroduction in Australia, based on trophic cascade theory, is “weak”. They conclude that, “because of climate instability, the strong top-down trophic responses reported from the Yellowstone National Park case study are unlikely to apply in arid and semi-arid south-eastern Australia and are speculative at best”.

We agree that dingoes (Canis dingo) are likely to exert different effects on ecological communities in Australia as compared to grey wolves (Canis lupus) in North America. A comparison of body sizes and dietary preferences between these canid species alludes to their functional ecological differences. Differences in the biological communities and climate between Yellowstone National Park and Australia also prevent direct comparisons of trophic cascade-processes between the two regions. These facts should not, however, preclude examination of the efficacy and consequences of dingo reintroductions in Australia.

We contend that Morgan et al. (2016):

  1. misunderstand the circumstances that make trophic cascades important to consider in Australia,
  2. do not acknowledge key reasons why dingo reintroduction has been proposed,
  3. haven’t recognised the different pathways by which dingoes could influence ecosystems via trophic cascades, and
  4. do not fully acknowledge literature and theory relevant to understanding the interplay of bottom-up and top-down processes in Australia.

Our reply is intended to assist managers and decision makers when deciding whether or not to reintroduce dingoes into Australian ecosystems.

Newsmen TM, Greenville AC, Letnic M, Ritchie EG, Dickman CR (2017) The case for a dingo reintroduction in Australia remains strong: A reply to Morgan et al., 2016, Food Webs, PDF DOI

Predators help protect carbon stocks in blue carbon ecosystems

Authors: Trisha B Atwood, Rod M Connolly, Euan G Ritchie, Catherine E Lovelock,
Michael R Heithaus, Graeme C Hays, James W Fourqurean and Peter I Macreadie

Published in: Nature Climate Change, September 2015

Tiger Shark

Tiger sharks in Shark Bay, Western Australia, create a landscape of fear where sea turtles and dugongs preferentially forage in seagrass microhabitats that are lower in predation risk and have allowed Cabon stocks. Image credit Albert Kok via Wikimedia Commons.

Abstract

Predators continue to be harvested unsustainably throughout most of the Earth’s ecosystems.

Recent research demonstrates that the functional loss of predators could have far-reaching consequences on carbon cycling and, by implication, our ability to ameliorate climate change impacts. Yet the influence of predators on carbon accumulation and preservation in vegetated coastal habitats (that is, salt marshes, seagrass meadows and mangroves) is poorly understood, despite these being some of the Earth’s most vulnerable and carbon-rich ecosystems.

Here we discuss potential pathways by which trophic downgrading affects carbon capture, accumulation and preservation in vegetated coastal habitats.

We identify an urgent need for further research on the influence of predators on carbon cycling in vegetated coastal habitats, and ultimately the role that these systems play in climate change mitigation.

There is, however, sufficient evidence to suggest that intact predator populations are critical to maintaining or growing reserves of ‘blue carbon’ (carbon stored in coastal or marine ecosystems), and policy and management need to be improved to reflect these realities.

Atwood TB, Connolly RM, Ritchie EG, Lovelock, CE, Heithaus MR, Hays GC, Fourqurean JM, Macreadie PI (2015) Predators help protect carbon stocks in blue carbon ecosystems, Nature Climate Change PDF DOI

Wired: The dingoes ate my kitten

The war between cat-lovers and bird-lovers may have found its compromise: larger predators. Dingoes may do a far better job than humans of keeping feral cats in check, and without the ethical baggage. In other words, if you want to kill a feral cat, get a wild dog.

That’s the message from Arian Wallech et al. in a recently published piece: Novel trophic cascades: apex predators enable coexistence. Wallach’s paper reinforces my research into the interactions between dingoes and feral cats in Australia. Using native predators to kill or scare off introduced predators could be our best bet; working with nature , not against it.

But can we apply our learnings to other contexts and ecosystems? Stan Gehrt of Ohio State University thinks so: he studies the much-maligned coyote — specifically a thriving urban population in Chicago — which seems to be keeping the local cats at bay.

Read the full article and reader comments at wired.com

Interspecific and Geographic Variation in the Diets of Sympatric Carnivores: Dingoes/Wild Dogs and Red Foxes in South-Eastern Australia

Authors: Naomi E Davis, David M Forsyth, Barbara Triggs, Charlie Pascoe, Joe Benshemesh, Alan Robley, Jenny Lawrence, Euan G Ritchie, Dale G Nimmo and Lindy F Lumsden.

Abstract

Dingoes/wild dogs (Canis dingo/familiaris) and red foxes (Vulpes vulpes) are widespread carnivores in southern Australia and are controlled to reduce predation on domestic livestock and native fauna.

We used the occurrence of food items in 5875 dingo/wild dog scats and 11,569 fox scats to evaluate interspecific and geographic differences in the diets of these species within nine regions of Victoria, south-eastern Australia.

The nine regions encompass a wide variety of ecosystems. Diet overlap between dingoes/wild dogs and foxes varied among regions, from low to near complete overlap. The diet of foxes was broader than dingoes/wild dogs in all but three regions, with the former usually containing more insects, reptiles and plant material. By contrast, dingoes/wild dogs more regularly consumed larger mammals, supporting the hypothesis that niche partitioning occurs on the basis of mammalian prey size.

The key mammalian food items for dingoes/wild dogs across all regions were black wallaby (Wallabia bicolor), brushtail possum species (Trichosurus spp.), common wombat (Vombatus ursinus), sambar deer (Rusa unicolor), cattle (Bos taurus) and European rabbit (Oryctolagus cuniculus). The key mammalian food items for foxes across all regions were European rabbit, sheep (Ovis aries) and house mouse (Mus musculus).

Foxes consumed 6.1 times the number of individuals of threatened Critical Weight Range native mammal species than did dingoes/wild dogs. The occurrence of intraguild predation was asymmetrical; dingoes/wild dogs consumed greater biomass of the smaller fox.

The substantial geographic variation in diet indicates that dingoes/wild dogs and foxes alter their diet in accordance with changing food availability.

We provide checklists of taxa recorded in the diets of dingoes/wild dogs and foxes as a resource for managers and researchers wishing to understand the potential impacts of policy and management decisions on dingoes/wild dogs, foxes and the food resources they interact with.

Davis NE, Forsyth DM, Triggs B, Pascoe C, Benshemesh J, Davis NE, Forsyth DM, Triggs B, Pascoe C, Benshemesh J, Robley A, Lawrence J, Nimmo DG, Ritchie EG, Lumsden LF (2015) Interspecific and Geographic Variation in the Diets of Sympatric Carnivores: Dingoes/Wild Dogs and Red Foxes in South-Eastern Australia. PLoS ONE 10(3): e0120975. PDF DOI