Coumatetralyl Efficacy Trial against Rodents in a Young Pine Plantation at Linwood, Natal Midlands

SYNOPSIS

Coumatetralyl rodenticide (in wax block formulation, trade name “Racumin rat and mouse bait blocks”) was tested at different densities for effectiveness against rodents in a stand of two to three-year-old Pinus patula in the Natal midlands. Live trapping for small mammals in sample plot was conducted before poison placement, then two and five weeks after poison placement. Small mammal species recorded that are potentially harmful to saplings were Mastomys natalensis, Otomys irroratus and Rhabdomys pumilio. Decreases in densities of these rodents were noted after five weeks of poisoning at 16% poison density (percent of saplings in sample plot with poison at base), and after two weeks of poisoning at 25 % and 50% poison densities. Faecal pellet counts of trap shy O. irroratus in each of the plots further indicated a decline in density due to poison placement. Some recommendations are made. Under no circumstances should raptor perches be used in the same areas as rodenticides, to prevent secondary poisoning from rodent carcasses.