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Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE

Comparison of 0.005% and 0.01% diphacinone and chlorophacinone baits for controlling California ground squirrels (Spermophilus beecheyi)

Terrell P. Salmon A D , Desley A. Whisson B C , Are R. Berentsen A and W. Paul Gorenzel B
+ Author Affiliations
- Author Affiliations

A University of California, Cooperative Extension, 5555 Overland Drive, Suite 4101, San Diego, CA 92123, USA.

B Wildlife, Fish and Conservation Biology, University of California, One Shields Avenue, Davis, CA 95616, USA.

C Present address: Department for Environment and Heritage, South Australia, PO Box 39, Kingscote, SA 5223, Australia.

D Corresponding author. Email: tpsalmon@ucdavis.edu

Wildlife Research 34(1) 14-18 https://doi.org/10.1071/WR06092
Submitted: 27 July 2006  Accepted: 13 December 2006   Published: 27 February 2007

Abstract

Abstract. Diphacinone and chlorophacinone, first-generation anticoagulant rodenticides, are frequently used for control of California ground squirrels (Spermophilus beecheyi) in agricultural and rangeland areas in California, USA. Owing to growing concerns over the risks to non-target species associated with the use of these rodenticides, the USA Environmental Protection Agency (EPA) proposed that the concentration of baits for above-ground use should be reduced from 0.01% to 0.005% active ingredient. We conducted field trials to compare the efficacy of 0.005% and 0.01% chlorophacinone and diphacinone baits in broadcast and spot applications for control of California ground squirrels on rangeland. We found no significant difference in efficacy owing to bait type, concentration or application method. Repeat testing is needed in other habitat types (e.g. crop areas) where alternative foods might reduce the effectiveness of a 0.005% bait application.


Acknowledgements

Funding was provided by the California Department of Food and Agriculture Vertebrate Pest Control Research Advisory Committee (CDFA contract 00–0471). This study was conducted under the University of California Animal Use and Care Protocol #9493. Special thanks to Ralph Phillips of Kern County Cooperative Extension for help in locating the Bakersfield study site. We thank Cathie Joughin, Tim Hearne and Bill Whitney for access to their ranches and for their willingness to manage their livestock to accommodate the study. We also thank Henry Gonzales, Bill Taylor and Pam Everett of the King City office of the Monterey County Agricultural Commissioner’s office for logistical help and identifying cooperators. We are grateful to Fred Rinder of the Fresno County Agriculture Commissioner’s office and Les Wright of the Kings County Agriculture Commissioner’s office for supplying bait, sometimes on short notice. We appreciate help with bait application and carcass searching provided by numerous personnel from the California Department of Food & Agriculture and the University of California. We thank Nick Condos and Duane Schnabel of the California Department of Food and Agriculture, who served as the initial and final Study Directors, respectively.


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