Alligator Snapping Turtle (Macrochelys temminckii) Occupancy Increases in Higher-Order Streams

Kyra S. Woytek¹, Daniel Saenz², Daniel J. Herrera³, William I. Lutterschmidt^1,*, and Christopher M. Schalk²

¹Department of Biological Sciences, Sam Houston State University, Huntsville, TX 77341.²USDA Forest Service, Southern Research Station, Nacogdoches, TX 75962.³North Carolina Museum of Natural Sciences, Raleigh, NC 27601. *Corresponding author.

Southeastern Naturalist, Volume 25, Issue 2 (2026): 254–269

First published early online: 26 June 2026

Abstract
Macrochelys temminckii (Alligator Snapping Turtle) is a large freshwater turtle that occurs in a broad range of stream orders in the southeastern US. The species has experienced range contraction and population declines throughout its range. Environmental DNA (eDNA) sampling is an effective method for indirect detection of the Alligator Snapping Turtle when trapping or radio tracking is not feasible. Environmental conditions and resource availability vary across stream orders, potentially influencing Alligator Snapping Turtle occupancy patterns and eDNA detection probabilities. In this study, we sampled eDNA to survey for the Alligator Snapping Turtle in the Sam Houston National Forest, TX, to determine if Alligator Snapping Turtle occupancy and detectability were correlated with stream order and its associated abiotic variables. We found that occupancy was indistinguishable among stream orders 1–4, but that occupancy was significantly higher in fifth-order streams, potentially due to more stable water temperature and greater resource availability. Furthermore, our models suggest that no abiotic variables significantly affected detection probability. This information provides a better understanding of how the Alligator Snapping Turtle may be distributed across stream orders and may help inform forest-management practices near streams where the species may occurion distributions and ecological impacts of these species in South Florida.

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