LB 30-298 - CANCELLED - Spatial niche partitioning allows the coexistence of Nine-banded Armadillos (Dasypus novemcinctus) and Gopher Tortoises (Gopherus polyphemus) in a pine plantation

Background/Question/Methods:

Nine-banded armadillos and gopher tortoises cohabit pine forests in the southeastern United States but may compete for burrowing locations. It may be problematic because gopher tortoises are a declining species, while armadillos are invasive species expanding their range through northern and eastern parts of the country. A microhabitat selection study considering seven habitat parameters was conducted on a 13.35 ha plot on Moody Air Force Base near Valdosta, Georgia, to determine if they were using the same habitat. In addition, preference of habitat parameters was compared between burrow categories, such as armadillo burrow types based on location (on-berm and off-berm; berms are manmade soil mounds about 1m high) and gopher tortoise burrow types based on the age of occupant. Eighty-six burrows were randomly selected, and discriminant analysis was used to identify parameters that differentiate the locations of both species’ burrows from each other and from random sites (N = 250).

Results/Conclusions:

Armadillo burrows (N = 40) were found in areas with higher vegetation density, denser canopy cover, steeper slopes, and thicker ground cover than gopher tortoise burrows (N = 46). Steeper slopes, low visibility, and farther distance from edges separated armadillo burrows from random sites. Armadillos prefer to build burrows on berms that have steeper slopes, higher vegetation density, higher ground cover, less sunlight, and lower elevation than off berm burrows. Adult gopher tortoise burrows had higher visibility than other burrow categories. This is the first study to provide evidence that synoptic armadillos and gopher tortoises prefer to build burrows in different microhabitats. Spatial niche partitioning between the species explains the coexistence because site selection is not random, and each species has a strong association with specific parameters. So, this niche partitioning was probably driven by their physiology. However, the presence of co-opted burrows could explain competition and suggest a complex or mixed mechanism, and understanding this mechanism might aid in their habitat management.