Unpaved Roads as Overlooked Habitat for Florida Scrub Lizards, David Tevs (Georgia Southern University)
Each year, GTC awards 1-2 grants of up to $3,000 each to undergraduate and/or graduate students researching gopher tortoise biology and ecology, or other relevant aspects of upland habitat conservation and management within the range of the gopher tortoise. David Tevs was a Landers Grant recipient in 2022. Keep reading to learn more about his research on Florida scrub lizards in peninsular Florida.
For my master’s research, I examined how unpaved roads can act as alternative habitat for lizards adapted to conditions commonly associated with post-wildfire landscapes within the Ocala National Forest (ONF) in peninsular Florida. Previous work has already demonstrated that Florida scrub lizards (Sceloporus woodi; hereafter scrub lizards) are more likely to occur along unpaved roads than the interior of recently logged patches of sand pine scrub in ONF. However, little attention has been given to understanding how other aspects of scrub lizard biology are affected by unpaved roads, or if unpaved roads allow these lizards to occupy long-undisturbed patches of forest that would otherwise be unsuitable. Many of the abiotic conditions associated with recent wildfire (e.g., large amounts of bare ground, increased light availability) are replicated by the creation and maintenance of unpaved sand roads. Because scrub lizards are traditionally associated with recent disturbance, I expected lizards to be equally abundant along unpaved roads regardless of the adjacent habitat. I also expected dietary composition and ectoparasitism rates to be more consistent among lizards occurring along unpaved roads compared to interiors of different forest types.
During the summers of 2021 and 2022, I assessed relative abundance of scrub lizards along unpaved roads bordered by all six possible combinations of the predominant habitat types in ONF: recently disturbed sand pine scrub, long-undisturbed sand pine scrub, and recently disturbed longleaf pine sandhill. Recently disturbed sand pine scrub typically has limited if any canopy cover and a much greater availability of bare sand on the forest floor compared to long undisturbed sand pine scrub. Surveys consisted of myself and one of my lab mates walking in tandem along each road edge and scanning the road surface and adjacent habitat for scrub lizards, which I then captured using a noose. I also captured scrub lizards from forest interiors (> 15 m from the road edge) of recently-disturbed sand pine scrub and recently-disturbed longleaf pine sandhill. Collecting scrub lizards from the interiors of long-undisturbed sand pine scrub was infeasible due to the dense vegetation interfering with the noose capture technique. Following capture, I counted the number of ectoparasites (e.g. larval chigger mites) on each scrub lizard, and stomach flushed each lizard for dietary analyses.
I found that scrub lizards were equally abundant along unpaved roads regardless of surrounding habitat. This contradicts much of the published literature, which has shown this species is usually less abundant in long-undisturbed patches of sand pine scrub. However, previous studies did not account for the effects of unpaved roads. My results suggest the presence of these features in ONF allows scrub lizards to occupy patches of habitat that would otherwise be unsuitable. I also observed that the dietary composition and rates of ectoparasitism on scrub lizards were consistent along unpaved roads, regardless of the surrounding habitat. In contrast, several dietary metrics differed between interior patches of early successional sand pine scrub and longleaf pine sandhill. For example, scrub lizards within the interior of longleaf pine sandhill consumed more prey items on average than those within early successional sand pine scrub interiors. However, lizards from both habitats consumed a similar volume of total prey items. This suggests that scrub lizards inhabiting unmodified longleaf pine sandhills must consume relatively smaller prey (but more of them) to achieve a similar volumetric intake as their counterparts in recently disturbed sand pine scrub.
From these results, I can extrapolate that unpaved roads in ONF have the potential to greatly impact scrub lizard populations. By allowing lizards to occupy and move through otherwise inhospitable habitat (i.e., long undisturbed sand pine scrub), unpaved roads may help facilitate connectivity in an otherwise fragmented landscape. Additionally, unpaved roads appear to have more uniform biotic conditions (i.e., forage base and exposure to ectoparasites) than forest interiors of different habitats. Additional studies are still needed to understand how unpaved roads affect other upland fauna. Nevertheless, my results, combined with previous work showing scrub lizards are more abundant along unpaved roads than forest interiors, suggests these anthropogenic additions to the landscape may facilitate the persistence of Florida scrub lizards in ONF.
I am grateful to the Gopher Tortoise Council and my thesis advisors Drs. Lance McBrayer and Aaron Schrey for supporting my research. As this issue of the newsletter goes to press, I am heading west to begin a Ph.D. program at the University of Montana. While in Montana, I plan to continue studying the ecology of reptiles with a focus on evolution and management of montane lizards.