Rarely are the activities of invasive species considered to be, at times, positive, but that may be the case with the armadillo populations in Coastal Georgia.
Like millennials and New Wave music, armadillos made themselves known on local barrier islands in the early 1980s. Since then, it appears they’ve been helping create habitat for not only themselves, but others.
University of Georgia graduate research assistant Zachary Butler and Little St. Simons Island ecologist Scott Coleman headed up a year-long study of armadillos on Little St. Simons that was presented at the Ecological Society of America’s annual meeting in New Orleans in August.
Butler said he became interested in looking into armadillo behavior while serving as an AmeriCorps member at the Georgia Sea Turtle Center.
“I was interested in the nine-banded armadillo because it is arguably one of the most unique mammals in the United States and the only representative from the order Cingulata that is currently established in North America,” Butler said. “Worldwide, this single species of armadillo has the largest distribution of any cingulate, with a range extending from as far north as Nebraska to northern Argentina.
“Yet, surprisingly, no studies have attempted to quantify the extent to which commensal species rely on nine-banded armadillo burrows and what benefits they may have as ecosystem engineers.”
During their research, Butler and Coleman looked into seeing whether the burrows armadillos create would be used by other creatures where no other borrowing animal exists — an issue of increasing frequency with the decline of the gopher tortoise.
“We knew that armadillos had arrived on LSSI in the early 1980s, but we weren’t really sure about their impacts on the island’s native flora and fauna,” Coleman said. “We wanted to gather additional information to better understand how these animals are impacting the ecosystems on LSSI.”
Through nine game cameras and a burrow scope — used on dozens of burrows around the island — they discovered several species using armadillo burrows, for varying reasons. Often seen were cotton rats and eastern diamondback rattlesnakes, which combined made up 39 percent of all sightings, while armadillos themselves were seen 22 percent of the time. In all, observed there were six different reptile or amphibian species, six different mammal species and three different bird species, along with ghost crabs.
Of course, armadillos are known to get into sea turtle nests during nesting season, which can present an issue. Across Georgia this nesting season — according to data submitted to seaturtle.org — armadillos figured fourth in reasons for nest losses, beat out by raccoons, wild hogs and ghost crabs. They were also fourth in reasons for egg losses, behind research, raccoons and ghost crabs.
“As part of my project, I’m working with Georgia DNR to answer questions about if armadillos really provide a significant threat to sea turtle nests compared to other predators,” Butler said. “Our objective is to analyze historical data collected on sea turtle nest predations from multiple barrier islands. Specifically, we are interested in comparing sea turtle nest predations by predator across the Georgia barrier islands since 2009.
“We hypothesize that over time and across islands, predation of sea turtle nest by armadillos is minimal compared to that of other predators such as raccoons, hogs and ghost crabs.”
Coleman said that while armadillos may create a positive impact thanks to burrow creation, it’s important to remember the larger impacts of invasive species.
“Exotic invasive species are the second-biggest threat to biodiversity, after development,” Coleman said. “Though some exotic invasive species may have some positive benefits, in most situations, the negative benefits outweigh the positive ones. Though we still have a lot to learn, and this study is just the beginning, there is evidence from this research that armadillos may have a positive impact on barrier island ecosystems.”