Ecosystem engineers play fundamental ecological roles by modifying landscapes in ways that affect a variety of taxa and by creating refugia that otherwise would not be present. Burrow-creating organisms (tortoises, prairie dogs, aardvarks) are widely distributed globally and could provide ecological services like thermal refugia for countless commensal species. A specific species where there has been little investigation into the ecological role of their burrowing behavior is the nine-banded armadillo (Dasypus novemcinctus). Over the last several decades, nine-banded armadillos have dramatically increased their range, resulting in abundant populations throughout the southeastern United States. We hypothesize that armadillos serve as ecosystem engineers that provide habitat for a multitude of native species. More specifically, we theorize that their burrows provide thermal refugia during periods of inclement weather, especially in areas where no other burrowing animal is present. This hypothesis was tested through research conducted on Little St. Simons Island, Georgia from October 2016 to October 2017. Nine game cameras were deployed in beach and dune habitats around the island to document the commensal use of various burrows. A burrow scope was also used to assess the extent to which commensal species were utilizing burrows, including ones not monitored with game cameras.
Results/Conclusions
Over our year-long research sampling period, we found a total of 15 commensal species using armadillo burrows on Little St. Simons Island. These species included six herpetofauna taxa, six mammalian taxa, 3 avian taxa, and one crustacean. While herpetofauna seemed to use the burrows primarily as thermal refugia, the mammals and birds predominantly used the burrows as foraging grounds. The most predominant commensal species using these burrows were determined to be hispid cotton rats (Sigmodon hispidus) and eastern diamondback rattlesnakes (Crotalus adamanteus). These species made up 24% and 15 % respectively of all animals detected during the study, including nine-banded armadillos (22%). Given the variety of commensals found during this research project, it is without question that a diversity of species do indeed take advantage of armadillo burrows. This research exemplifies the need for further investigation into the commensal use of armadillo burrows, as these burrows created by non-natives could help ensure the widespread availability of refugia offering protection from extreme environmental conditions shaped by climate change. Furthermore, examining the possible ecological benefits provided by the armadillos will assist land managers in determining if armadillo establishment should be prevented through invasive species management or monitored as a recently established native.