Preliminary field assessment of a cabergoline baiting campaign for reproductive control of the red fox (Vulpes vulpes)

The use of poison baiting to control foxes is impractical in urban areas and some wildlife reserves because of hazards to non-target animals. More acceptable methods of fox control in such environments are needed. Cabergoline is a dopamine agonist that has previously been demonstrated to have an abortifacient effect in cats (Felis catus) and dogs (Canis familiaris). The prolactin-inhibiting action of cabergoline may also result in cessation of lactation. Cabergoline has been shown to be completely palatable to foxes and is easily incorporated into a non-poisonous bait. The ability of bait-delivered cabergoline to effect the birth of viable fox cubs was tested in urban Melbourne and rural Bendigo. A sample of 51 natal dens were chosen for this study on the basis that they had been active for three consecutive years. Thirty treatment dens were randomly selected and each treated once during August and again during September 1994 with eight nonpoisonous Foxoff baits containing 170 mu g of cabergoline and 200 mg of tetracycline to act as a biomarker. The remaining 21 dens were used as controls. Baits were randomly placed by burial within a 50-m radius of the den. Activity of all dens was assessed until December 1994 for direct/indirect signs of fox cubs. Bait uptake was greater than 88% overall for the treatment dens. The resulting incidence of cubs was significantly lower in the treatment dens than in the controls. The potential for cabergoline to be used in urban areas and island populations as an adjunct to conventional control methods is discussed.