Application of Repellent Gel to the Surfaces of Transmission Towers for Wild Bird Management

The repellent gel used in this study consisted of non-toxic ingredients and contained white pepper and capsaicin. A gel-treated artificial perch was compared with an untreated control using wild-caught Large-billed Crows (Corvus macrorhynchos) in an experimental cage. The repellent gel’s effectiveness was also evaluated in field experiments with Grey Herons (Ardea cinerea) by establishing treated and untreated areas at daytime roost sites on outdoor steel structures.

Both Large-billed Crows and Grey Herons spent significantly less time on the treated perch or area than on the corresponding untreated control; in particular, the time spent by crows on the treated perch decreased by more than 99% relative to the control perch. However, in the field experiments with herons, there was no difference in the number of individuals landing in areas with and without repellent gel.

The results suggest that repellent gels can effectively reduce location-specific use of transmission towers by Large-billed Crows and Grey Herons, primarily through tactile stimulation. However, because repellent gels may degrade or disappear after several months under field conditions, regular reapplication is required. Adhesion of the gel to birds’ feathers and legs may also result in the transfer of gel to other structures. Further research, including field trials conducted directly on transmission towers, is needed to improve the effective and practical use of repellent gels.