Urban rodent control
Rodent control is vital in cities. New York City and cities across the state dramatically reduced their rodent populations in the early 1970s. Rio de Janeiro claims a reduction of 80% over only 2 years shortly thereafter. To better target efforts, London began scientifically surveying populations in 1972 and this was so useful that all Local Authorities in England and Wales soon followed.
Natural rodent control
Several wildlife rehabilitation organizations encourage natural form of rodent control through exclusion and predator support and preventing secondary poisoning altogether. The United States Environmental Protection Agency notes in its Proposed Risk Mitigation Decision for Nine Rodenticides that "without habitat modification to make areas less attractive to commensal rodents, even eradication will not prevent new populations from recolonizing the habitat." The United States Environmental Protection Agency has prescribed guidelines for natural rodent control and for safe trapping in residential areas with subsequent release to the wild. People sometimes attempt to limit rodent damage using repellents. Balsam fir oil from the tree Abies balsamea is an EPA approved non-toxic rodent repellent. Acacia polyacantha subsp. campylacantha root emits chemical compounds that repel animals including rats.
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