Improving morphological diet studies with molecular ecology
I’m sure you all know by now that many wildlife species are threatened by invasive predators. Diet studies are often used to understand the specific impacts of predators, to guide management actions. Traditionally, this has meant sorting through scats and gut contents to identify as many prey remains as possible. Of course there are limitations to this approach: only hard body parts tend to survive the digestive tract and many of these will be too damaged for identification. Which is where DNA comes in useful… But how to compare data from new DNA-based diet studies with old morphology-based studies? In this paper, the authors focused on island birds, which turn out to make tasty snacks for rats and cats. They evaluated the taxonomic resolution of previous morphological studies (how often could prey remains be identified to species level…), developed genetic resources for DNA-based identification of bird remains, then tested both morphological and molecular approaches on the same dietary samples. Molecular tools enabled higher taxonomic resolution in many cases, but using both approaches together is likely to provide greater confidence in results.
Catastrophic cat predation: A call for predator profiling in wildlife protection programs
And while we’re on the topic of cats… whilst it might be possible to completely eradicate introduced cats from smaller islands, this is (sadly) unlikely to ever be achieved over large areas like, say, the entire Australian continent. In this case, a more strategic use of resources would be to work out the best way to control cats to achieve conservation aims. This paper tells of the sad demise of a group of western quolls (Australian marsupial carnivores) following their reintroduction to the Flinders Ranges National Park. All quolls were wearing radiocollars, which allowed recovery of their remains for autopsy and investigation into the causes of death. Eleven out of the 41 quolls released were killed by cats, despite the fact that a quoll would make a fairly large and aggressive target. Assorted evidence, including DNA, bite pattern analysis and cat gut content analysis, pointed the finger of blame squarely at a select group of quoll-killers: big male cats. So, in this case, rather than spending a fortune trying to eradicate all cats from the Flinders Ranges, selectively targeting these big males might actually have a better outcome… at least for quoll conservation.
This longread in Nature about songbird poaching and conservation in Cypress captures the essence of conservation. Specifically, it highlights the competing interests of multiple stakeholder groups, how science informs conservation, how science is disputed in conservation, how cultural norms influence the use of natural resources, that geopolitics can often be a factor when designing conservation plans, and the ironic and sad economic relationship that wildlife trade is increasingly lucrative as resources become scarcer until one day the resource is gone.