Roof rat populations in Santa Clara County, California

Northern Santa Clara County, California, has changed from an agricultural to an industrial-residential community in the past 10 to 15 years. Maturing shrubbery and fruit bearing trees in residential areas have provided ideal habitat for increased populations of roof rats. Advisory or educational control measures only met with partial response and little success in actually exterminating rats. It took an actual organized health department effort with diphacinone bait blocks to achieve adequate control in a given area of 400+ homes. An interesting legal complication is described as related to public rodent control on private property