Burrowing crayfish represent 15% of total crayfish species and 32% of imperilled species. Few life history studies exist for these species and more information is needed regarding their ecology, population status, distribution, and biogeography for effective conservation efforts. Challenges to gaining such information include sampling difficulty and small sample sizes. Collection efforts may be more efficient if activity patterns can be identified for species of interest. The goal of our study was to assess specific environmental indicators of burrowing crayfish activity patterns. We evaluated activity patterns of two primary burrowing crayfish species, Lacunicambarus erythrodactylus (Simon & Morris, Proc. Biol. Soc. Wash., 127, 2014, 572) and Procambarus holifieldi (Schuster, Taylor, & Adams, Zootaxa, 4021, 2015, 1) using laser‐triggered digital photography for one‐year periods in the Bogue Chitto Creek floodplain, Dallas County, Alabama, U.S.A. We predicted that activity would be related to time of day, season, groundwater depth, and precipitation. Activity by L. erythrodactylus covaried significantly with time of day, daylength, groundwater temperature, and relative air temperature, while activity by P. holifieldi covaried with time of day, season, groundwater temperature, and relative air temperature. Additionally, burrow chimney construction by P. holifieldi covaried with daylength, groundwater temperature, relative air temperature, and precipitation. Out‐of‐burrow activity for both species was greatest at night and during periods of relatively cool groundwater temperatures and relatively warm air temperatures, which may be linked to thermal regulation behaviour. The probability of chimney construction by P. holifieldi increased with increasing daylength and decreasing precipitation and was highest during periods of cool groundwater temperatures and air temperatures. A distinct lull in activity from October through March for both species was likely to be the result of reproductive behaviours such as period of egg production and incubation within burrows. Identifying peak out‐of‐burrow activity periods for burrowing crayfish will allow collection efforts to be focused on periods of greatest activity, thereby facilitating the study of burrowing crayfish behaviour.

Floodplain ecosystems host diverse surface‐water habitats (e.g., lotic, lentic, ephemeral) and groundwater features that support high levels of species diversity. Our understanding of species–habitat relationships within these complex ecosystems, however, remains incomplete, potentially hindering conservation efforts. Understanding associations between burrowing crayfish and habitat features of floodplains is particularly valuable because crayfish, through burrowing, play an important role in establishing aquatic‐terrestrial connections which enhance local biodiversity. Species of crayfish that persist in floodplains must burrow deep enough to access shallow groundwater. Consequently, burrow presence may indicate a preference for specific surface and subsurface habitat characteristics. The primary goal of our study was to evaluate specific habitat attributes as predictors of burrowing crayfish presence/absence, and our secondary goal was to evaluate species‐specific habitat associations with respect to the same environmental variables. We evaluated burrowing crayfish presence/absence and crayfish species composition with respect to groundwater depth, flood frequency (standing surface water), soil characteristics, and tree size in the Bogue Chitto Creek catchment, Dallas County, Alabama, U.S.A. Active burrows were expected at sites with access to water (a shallow water table) and at sites with environmental variables more conducive to burrow stability (fine‐grained soils and mature trees). Species composition was predicted to vary with groundwater depth and flood frequency. Groundwater depth was the primary driver of burrowing crayfish presence/absence in our system; active burrows were more likely to be present in areas with relatively shallow groundwater depths. Within occupied sites, differences in crayfish species composition were significantly associated with the degree of flooding during the 1‐year study period. Species associated with a high dependence on surface waters were collected alongside species dependent on burrowing to access groundwater, suggesting that the environmental features of floodplains satisfy a diverse set of requirements. In particular, sites offering a mosaic of accessible groundwater depths and floodplain pools may provide critical habitat for diverse assemblages of burrowing crayfish species. Our study revealed a strong association between the presence/absence of active crayfish burrows and the depth to groundwater, a result that supports using burrowing crayfish as indicators of accessible groundwater. This will be increasingly important in the context of how climate change might influence water availability and local species diversity.

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