Researchers from the University of Georgia have made a breakthrough that could lead to greater understanding of invasive species, which are the biggest threat to biodiversity and have made Hawaii’s native species the nation’s most endangered and threatened.
A reason Hawaii’s invasive species are so hardy is that after death, their carcasses serve as nutrient resources for other invasive scavengers, according to a team from UGA’s Savannah River Ecology Laboratory. This finding may be critical to understanding successful island invasions, which lead to ecosystem impacts.
“It is essential to know where nutrient resources flow in a highly invaded ecosystem,” Olin E. Rhodes Jr., laboratory director, said in a statement.
The study was based on data collected from three locations inside Hawai‘i Volcanoes National Park and Pu‘u Maka‘ala Natural Area Reserve in June-August 2013 and July-September 2014. The team used camera traps and transmitters to monitor the consumption of 647 carcasses of invasive species, including amphibians, reptiles, small mammals and birds. Full results can be found at 808ne.ws/CarcassStudy Opens in a new tab.
“We wanted to see what was eating the invasive species that have significant populations on the island. And, we wanted to identify the percentages of carcasses eaten by invasive vertebrates and invertebrates,” team leader Erin F. Abernethy, an alumna of SREL and Georgia’s Odum School of Ecology, now at Oregon State University, said in a statement.
What they found, said Abernethy, “indicates a positive feedback loop.”
“The more non-native species invade an island, live and reproduce and die, the more nutrient resources they create for other invasive species through carcasses — synergistically refueling off of one another and further invading the ecosystem,” she said.
Abernethy said researchers discovered that vertebrates were skilled at acquiring large and small carcasses.
“They were adept and highly efficient at finding the smallest of resources — locating carcasses of coqui frogs, a small frog native to Puerto Rico — and geckos that only weighed a few grams, before invasive invertebrates had the opportunity to get to them,” she said.
Regardless of size, these animals represent a significant food source, Abernethy said. Prior research indicates there are as many as 91,000 coqui frogs for every 2.47 acres, she said.
Researchers noted invasive vertebrates, like mongoose and rats, removed
55 percent of the watched carcasses. Invasive invertebrate scavengers, including yellow jackets and fly larvae, removed 45 percent of them. These invaders did not leave carcasses for native species, including owls and hawks.
