Gopher Tortoise (Gopherus polyphemus) burrow associate communities are depauperate in modified landscapes

Abstract The Gopher Tortoise ( Gopherus polyphemus ) is considered a keystone species because its burrows provide refuge for an entire suite of other species (hereafter burrow associates) that occupy the habitats in which it resides. The Gopher Tortoise has declined across its range in large part due to habitat loss and land use change resulting in burrow abandonment or reduced burrow density, and the concomitant negative effects on burrow associate diversity have been well documented. However, under scenarios where Gopher Tortoise populations persist in modified habitat, the effect on community associates has received considerably less attention. In such instances, vegetation changes drive the loss of associate species, not the lack of suitable burrows. Here, we evaluated associations between Gopher Tortoise burrows and vertebrate burrow associates within test ranges and forested sites on Eglin Air Force Base, Florida. Specifically, we (1) determined how vegetation composition varies between forested sandhills and military test ranges, and (2) compared species richness, diversity, and community composition of burrow associates between habitats. We found that vegetation composition surrounding Gopher Tortoise burrows is highly variable, but in general test ranges had a simpler habitat structure and less diverse native plant communities than forested sites. As a result, we show that although military test range sites contain Gopher Tortoise burrows at comparable or higher densities than sites in natural longleaf pine sandhills, the community of vertebrate burrow associates in test range sites appears to be depauperate. Our results highlight that concern over habitat modifications may be warranted even in instances where Gopher Tortoise populations appear to be persisting. In the context of management that seeks to be beneficial to a wide array of burrow associates, efforts aimed at bolstering Gopher Tortoise populations in forested sandhills would be most prudent.