Obligate crayfish burrow use and core habitat requirements of crawfish frogs.

摘要

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 and how do they function to affect crawfish frog survivorship; (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 with respect to breeding wetlands? We tracked crawfish frogs to 34 burrows, discovered another 7 occupied burrows, and therefore report on 41 burrows. Crawfish frogs exclusively occupied crayfish burrows as primary burrows, which they inhabited for an average of 10.5 months of the year. With one exception, crawfish frogs also used crayfish burrows as secondary burrows - temporary retreats occupied while exhibiting breeding migrations or ranging forays. Burrows were exclusively located in grassland habitats, although crawfish frogs migrated through narrow woodlands and across gravel roads to reach distant grassland primary burrow sites. Home range estimates while inhabiting burrows were 0.05 m2 (the area of the burrow entrance plus the associated feeding platform) or 0.01 m3 (the estimated volume of their burrow). Crawfish frog burrows were located at distances up to 1,020 m from their breeding wetlands. To protect crawfish frog populations, we recommend a buffer (core habitat plus terrestrial buffer) of at least 1.2 km around each breeding wetland. Within this buffer, at least 3 critical habitat elements must be present: (1) extensive grasslands maintained by prescribed burning and/or logging, (2) an adequate number of upland crayfish burrows, and (3) no soil disturbance of the sort that would destroy crayfish burrow integrity.Digital Object Identifier http://dx.doi.org/10.1002/jwmg.357