Heemeyer, J. L., P. J. Williams, M. J. Lannoo. 2012. Obligate Crayfish Burrow Use and Core Habitat Requirements of Crawfish Frogs. Journal of Wildlife Management.
Abstract
Crawfish frogs (Lithobates areolatus) have experienced declines across large portions of their former range. These declines are out of proportion to syntopic wetland-breeding amphibian species, suggesting losses are resulting from unfavorable aspects of non-breeding upland habitat. Crawfish frogs get their common name from their affinity for crayfish burrows, although the strength of this relationship has never been formally assessed. We used radiotelemetry to address 4 questions related to upland burrow dwelling in crawfish frogs: 1) what burrow types are used; 2) what are the physical characteristics and habitat associations of crawfish frog burrows; 3) what are the home range sizes of crawfish frogs when burrow dwelling; and 4) where are crawfish frog burrows situated on the landscape? We tracked 34 animals, discovered another 7, and therefore identified 41 primary burrows. Crawfish frogs exclusively occupied crayfish burrows, which they used as both primary burrows (which they inhabited for an average of 10.5 mo of the year) and secondary burrows (temporary retreats occupied while exhibiting migration or ranging behaviors). Burrows were exclusively located in grassland habitats, although crawfish frogs migrated through woodlands and across roads to reach distant grassland primary burrow sites. Home range estimates while inhabiting burrows were on the order of 0.05 m2 (the area of the burrow entrance plus the associated feeding platform) or 0.01 m3 (the estimated volume of their burrow—when inhabiting burrows crawfish frogs move a greater distance vertically in their burrows than they do horizontally across the landscape). Crawfish frog burrows were located at distances up to 1,020 m from the breeding wetlands. To protect crawfish frog populations, we recommend a core habitat of at least 1.1 km around each breeding wetland. Within this core at least three critical habitat elements must be present: 1) an adequate number of upland crayfish burrows; 2) no landscape turnover of the sort that would destroy crayfish burrow integrity; and 3) landscape connectivity such that crawfish frog migration routes between burrows and breeding wetlands are maintained without reducing the probability of survival.