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Open Access Publications from the University of California

Changes in Taxonomic Nomenclature and Conservation Status of Ground Squirrel Species: Implications for Pesticide Labeling and Use of Zinc Phosphide Pesticide Products

  • Author(s): O’Hare, Jeanette R.
  • Eisemann, John D.
  • Fagerstone, Kathleen A.
  • et al.

The taxonomic classification of species and their protection status have important pesticide regulatory implications, particularly regarding product label language. Changes in nomenclature may cause confusion for both pesticide applicators and regulators. Such changes may also result in the naming of new species in need of protection, or conversely species whose protected status may no longer be warranted. Over the past several years there have been gradual taxonomic changes within the genus Spermophilus. This change has resulted in splitting Townsend’s ground squirrel (Spermophilus townsendii) into 3 distinct species. In addition to S. townsendii, the Piute ground squirrel (Spermophilus mollis) and Merriam’s ground squirrel (Spermophilus canus) are now recognized. The Townsend’s ground squirrel, as now classified, is restricted to a small region in southwestern Washington. The species with the largest distribution, that was formally included in S. townsendii, is now the Piute ground squirrel (S. mollis). Zinc phosphide pesticide products are used to control a number of ground squirrel species including Townsend’s. However, based on the revised nomenclature, populations of the 2 new species (Piute and Merriam’s ground squirrels) may not be controlled using these zinc phosphide products under existing labels, even though those same populations were previously considered Townsend’s ground squirrels and could be controlled with zinc phosphide products. Potential conflicts with state and federal laws regarding protection of certain species must also be considered. The reclassification of Townsend’s ground squirrel recognizes new species and existing subspecies that are protected or are being considered for protection. In addition, subspecies of the Idaho ground squirrel (Spermophilus brunneus) are afforded various levels of protection under federal and state laws. A discussion of temporal taxonomy changes, geographic distribution, and conservation status of the “Townsend’s ground squirrel” complex and the Idaho ground squirrel is presented here to support the decision process needed to develop appropriate label language for zinc phosphide pesticide products.

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