Distribution, natural history, and conservation of Cambarus dubius in Pennsylvania.

Due to their burrowing lifestyles that make them difficult to sample, the distributions and habitat associations of most burrowing crayfishes are poorly understood. A distributional study was conducted in south-western Pennsylvania to better understand the range and habitat associations of the primary burrowing crayfish Cambarus dubius within the state. A total of 790 new sites and six previously surveyed sites were sampled between the Chestnut Ridge and Allegheny Mountains, with the majority of these localities being roadside ditches. Crayfish were collected using a combination of burrow excavation, baited lines, and by hand. We utilised permutation-based t-tests to determine differences in habitat variables between sites with and without C. dubius and sites with and without any burrowing crayfish species. Cambarus dubius was collected from 61 total sites, and active crayfish burrows were observed at 137 additional sites. Cambarus carinirostris was collected from 13 sites, Lacunicambarus thomai was collected from six sites, and an exuvia of Procambarus acutus was collected from a stream at one site. New behavioural observations for C. dubius juveniles were observed while collecting specimens with baited lines. Sites with C. dubius had significantly more canopy cover and deciduous forest land cover and significantly less pasture-hay land cover than sites without C. dubius. Sites with burrowing crayfishes (all species) had significantly more canopy cover and deciduous forest land cover and significantly lower elevation, depth to the water table, percent sand substrate and pasture-hay land cover than sites without burrowing crayfish. In Pennsylvania, Cambarus dubius has not expanded its range in comparison to its historical range, and populations appear to be concentrated primarily in the southern valleys of the Chestnut Ridge and Allegheny Mountains. [ABSTRACT FROM AUTHOR]