Stand Conditions Drive Swamp Rabbit Habitat Use in a Managed Bottomland Hardwood Forest

Elizabeth M. Hillard^1,*, Clayton K. Nielsen², and John W. Groninger³

¹Wildlands Network, Asheville, NC 28804. ²Cooperative Wildlife Research Laboratory and Department of Forestry, Southern Illinois University, Carbondale, IL 62901. ³Department of Forestry, Southern Illinois University, Carbondale, IL 62901. *Corresponding author.

Southeastern Naturalist, Volume 23, Issue 2 (2024): 135–150

First published early online: 28 May 2024

Abstract
Bottomland hardwood (BLH) forest ecosystems within the Lower Mississippi Alluvial Valley exist in narrow corridors composed of frequently flooded mature forests and complemented by afforested younger forest patches due to BLH afforestation efforts. Sylvilagus aquaticus (Swamp Rabbit), a BLH forest-specialist species, require a diversity of habitat conditions, but little information exists on fine-scale Swamp Rabbit use of mature and young forest habitats and the conditions that may influence Swamp Rabbit habitat use. We addressed this literature gap by assessing use of habitat by Swamp Rabbits in afforested and mature BLH stands in southern Illinois during March 2014–March 2016. At 746 plots (area = 3.15 m², 60 m x 60 m spacing), we used Swamp Rabbit fecal pellets to quantify Swamp Rabbit habitat use and identified 9 habitat variables known to be important to Swamp Rabbits. We then created 18 a priori generalized linear models to evaluate variation in Swamp Rabbit habitat use relative to habitat variables each study year. Individual forest stands strongly influenced Swamp Rabbit habitat use in all 3 study years in addition to macro-habitat variables (i.e., distance to water, distance to afforested–mature stand interface) and micro-habitat variables (i.e., woody stem density, herbaceous ground cover) in some years. We found that both mature and afforested stands were used by Swamp Rabbits but that edaphic conditions specific to stands likely affected flooding and water inundation in localized areas impacting habitat conditions and thus Swamp Rabbit use. While we found increased ground vegetation and woody stem density had positive impacts on habitat use by Swamp Rabbits in 2014, these variables were no longer significant predictors of Swamp Rabbit occupancy when flooding was severe in 2015 and the following year, 2016. These results point towards water inundation from flooding as the main driver of Swamp Rabbit habitat use when it limits terrestrial habitat and the availability of vegetation resources important for food and hiding cover. Because Swamp Rabbit habitat use is driven by habitat at the stand scale, habitat management can focus on managing stands with more consistently dry conditions to provide all necessary habitat elements when lower elevations are unavailable due to inundation. This research underscores the annual variability of these forest ecosystems and the importance of incorporating forest vegetation dynamics, hydrogeomorphology and flooding incidence and severity into management plans for Swamp Rabbits.

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