Population Decline and Landscape-Scale Occupancy of the Crawfish Frog (Lithobates areolatus) in Northwest Arkansas

Lithobates areolatus (Crawfish Frog) is an imperiled amphibian, unique among ranid frogs due to its obligate use of crayfish burrows, highly terrestrial behavior, and reliance on open-canopy habitats within the central USA. Currently listed as near-threatened by the IUCN, and as state endangered, threatened, or of greatest conservation need in every state where it occurs, L. areolatus could potentially serve as an umbrella species for biodiversity conservation in the region. However, few studies have sought to identify site characteristics most strongly associated with the occupancy of L. areolatus or rigorously assessed the status of populations across core areas of the species' range in Arkansas, Oklahoma, and Kansas. Within northwest Arkansas, we used an occupancy-modeling framework to 1) determine landscape characteristics that could serve as predictors of the occupancy of L. areolatus and 2) assess the status of current and historical populations. We completed 405 time-constrained auditory surveys across 81 potential and historical breeding wetlands of L. areolatus over two breeding seasons (March-April 2016 and 2017). Estimated occupancy and detection were 0.26 and 0.32, respectively. We did not detect L. areolatus at 37.5% (6/16) of historic breeding wetlands during our study, indicating these populations are likely extirpated. Occupancy probability was strongly related to density of prairie mounds within 1 km of breeding wetlands and was weakly related to clay and chert/gravel loam soil. Our results suggest that: 1) L. areolatus is widespread throughout northwest Arkansas but is threatened by the expanding human population, 2) detection probability is high under optimal conditions (cool temperatures [9-12 degrees C] and recent rain [within 24 hr]), and 3) prairie mound density is a useful proxy for upland habitat quality, likely reflecting minimal soil disturbance and presence of crayfish burrows.

Automated summary

Lithobates areolatus, or Crawfish Frog, is an imperiled amphibian with unique behaviors and habitat preferences. Its use of crayfish burrows and reliance on open-canopy habitats set it apart from other ranid frogs. This species has been listed as near-threatened by the IUCN and is protected in every state where it occurs. It could potentially serve as an umbrella species for biodiversity conservation in the region.