The Dogma of the 30 Meter Riparian Buffer: The Case of the Boreal Toad (Bufo boreas boreas)
Citation
Michael C Goates, The Dogma of the 30 Meter Riparian Buffer: The Case of the Boreal Toad (Bufo boreas boreas): .
Summary
We tested the adequacy of standard 30 m riparian buffers for semi-aquatic vertebrate species, using the boreal toad (Bufo boreas boreas) as an example. We monitored toad populations in south-central Utah using radio telemetry during the summers of 2003 and 2004. We found 30 m buffers inadequate for protecting boreal toads and suggest this is likely true for other species as well. Managers must consider several factors when constructing buffers: (1) Buffer requirements may vary by time of year. While we located toads most often in wet habitats, toads commonly utilized upland habitats in late summer, occasionally at distances greater than 100 m from water. (2) A single year’s observation may not be sufficient to establish adequate [...]
Summary
We tested the adequacy of standard 30 m riparian buffers for semi-aquatic vertebrate species, using the boreal toad (Bufo boreas boreas) as an example. We monitored toad populations in south-central Utah using radio telemetry during the summers of 2003 and 2004. We found 30 m buffers inadequate for protecting boreal toads and suggest this is likely true for other species as well. Managers must consider several factors when constructing buffers: (1) Buffer requirements may vary by time of year. While we located toads most often in wet habitats, toads commonly utilized upland habitats in late summer, occasionally at distances greater than 100 m from water. (2) A single year’s observation may not be sufficient to establish adequate buffers. Toads moved into upland habitats more often and at greater distances from water ( 30 m) during the wetter, cooler weather conditions of 2004 than in 2003. (3) Buffer requirements may differ by sex. Male toads appeared to have stronger selection for wetland habitats than females. Females moved greater distances from water than males, often outside of buffer areas. (4) Buffer requirements may differ by location. 30 m buffers contained 82.4% of all observations, though results varied between 50.0 and 97.2%, depending on breeding location. Finally (5) All habitat requirements should be considered when establishing buffers. Many small, unmapped streams and seeps utilized by toads for hibernation were located outside buffer zones. After ground truthing and extending 30 m buffers around these habitats, the percentage of all observations within 30 m buffers increased to 92.4%. Managers need to be aware of the accuracy of digital and other mapping sources used in creating buffers and to incorporated all critical habitats in conservation buffers. Our boreal toad example suggests that ground truthing may be the most important factor in establishing effective buffer zones.
