A study of carnivorous scavenging activity in northern Tasmania and the Bass Strait Islands has highlighted the importance of carnivore conservation and the potential benefits of small prey species rewilding.
|Tasmanian Devil Conservation Park, Taranna, Tasmania, Australia (Sarcophilus harrisii). JJ Harrison/Wikimedia Commons/CC BY-SA|
Dr. Matthew Fielding of the ARC Center of Excellence for Australian Biodiversity and Heritage and the University of Tasmania led the study, which used strategically placed motion capture cameras and animal carcasses to monitor scavenger activity in three regions with varying populations of apex scavengers—Tasmanian devils and spotted-tailed quolls.
Smaller scavengers, such as native forest ravens and feral cats, were rewarded with less competition and more scavenging opportunities where these top scavengers were absent or sparse. However, their use of carcasses was inefficient, allowing partially consumed carcasses to remain in the environment for longer.
"Native scavengers like the Tasmanian devil and spotted-tailed quolls play an important role in the environment, but have recently declined on the Tasmanian mainland and have gone extinct on the Bass Strait Islands," says Dr. Fielding.
"We discovered that when these animals are removed from an ecosystem, smaller scavengers, such as feral cats, have greater access to food, which could lead to population growth and increased threats for small prey species such as woodland birds and small mammals."
"Because the Bass Strait Islands are home to some of Australia's most endangered bird species, such as the King Island Scrubtit and King Island Brown Thornbill, understanding these potential threats is critical."
While these smaller scavengers benefit from greater carcass access, they lack the scavenging efficiency of larger specialist scavengers such as the Tasmanian devil.
"We discovered that carcasses remained in areas without devils and quolls for the duration of the study, which could lead to an increased risk of carrion-borne diseases, with implications for livestock and human health." These findings show that native apex scavengers can fulfill their ecological functions even at low densities."
"Our findings highlight the importance of carnivore conservation and suggest that rewilding strategies—reintroducing top carnivores to areas where they are absent—could benefit small prey species and ecosystem health."
According to Dr. Fielding, the study adds to a growing body of evidence that feral cats actively scavenge, particularly when they perceive the little risk to themselves.
"Until recently, it was thought that cats rarely scavenged. In our study, feral cats scavenged nearly half of all carcasses in areas devoid of top carnivores. This suggests that when the perceived risk is reduced, scavenging can be an important food source for cats. Reducing such opportunities for cats may ultimately benefit native wildlife."
Journal information: Proceedings of the Royal Society B