The need to ground truth 30.5 m buffers: A case study of the boreal toad (Bufo boreas) Original Research Article

A buffer zone of 30.5 m is commonly used to protect species in riparian and wetland systems. This 30.5 m standard was developed to protect water quality, not biodiversity, and few studies have tested its effectiveness for protecting riparian and wetland species. We tested the standard implementation of 30.5 m buffers to determine if they protect critical habitat for semi-aquatic vertebrate species, using the boreal toad (Bufo boreas) as an example. Using radio telemetry of 84 toads in south-central Utah in 2003 and 2004, we found that the standard implementation of 30.5 m buffers did not protect all critical habitats for boreal toads. Managers should consider the following factors when establishing buffer zones: (1) Buffer requirements may vary by time of year. (2) A single year’s observation may not be sufficient to establish adequate buffers. (3) Buffer requirements may differ by sex. Finally (4), sites should be ground truthed prior to determining buffer zones. Critically, we found that many small streams and seeps used by toads were outside of buffer zones due to low resolution of GIS mapping layers. After ground truthing and extending 30.5 m buffers around these habitats, the average percentage of all observations within 30.5 m buffers increased from 82.4% to 92.4%. Our data suggest that ground truthing may be the most important factor in establishing effective buffer zones.