Date of this Version
Proceedings 18th Vertebrate Pest Conference, ed. R.O. Baker & A.C. Crabb. Published at University of California, Davis, 1998.
The purpose of this study was to determine if continued monitoring and removal of beavers (Castor canadensis) from previously controlled beaver damage sites resulted in less additional damage than not monitoring such sites. Beavers were removed from 34 sites in nine southeast Texas counties from August 1996 through March 1997. Sixteen sites subsequently were monitored monthly and, if beavers had reinvaded, they were removed and the additional damage value was recorded. The remaining 18 sites were not monitored monthly, but they were visited for a final survey at the end of the study. The value of additional damage was recorded at that time. Damage following reinvasion occurred more often when sites were not monitored (5 of 7 sites, compared to only 2 of 7 reinvaded, monitored sites). In addition, when damage occurred at reinvaded sites, monetary value appeared to be greater without monitoring (average $940, n=5) than with monitoring (average $125, n=2). The larger average damage values for reinvaded unmonitored sites compared to reinvaded monitored sites would be important to landowners when deciding if property should be monitored. Factors that made some sites susceptible to reinvasion were also evaluated. Significantly more beavers were taken initially, per site, in the reinvaded sites compared to all other sites. This implies that better habitat and higher beaver density were the most important factors in determining a site's susceptibility to reinvasion.