Thousands of kilometres of power lines exist and more are planned. Ungulates that range over large areas are likely to encounter power lines, but a synthesis of power line effects on ungulates is lacking. Reindeer (Rangifer tarandus tarandus) are suspected to avoid power lines up to distances of 4 km. In contrast, some forest ungulates preferentially forage in power line rights-of-way, cleared areas under power lines. We reviewed the factors that possibly influence avoidance and attraction effects of power lines on ungulates, construct a conceptual framework, and make suggestions on how to mitigate avoidance effects through power line routing and rights-of-way management. Power line construction, noise and electromagnetic fields are possible sources of disturbance, while rights-of-way management influences habitat use under power lines. Disturbance and altered habitat use can induce barrier and corridor effects, thereby influencing connectivity. Species-specific effects influence behavioural disturbance and habitat use. We found little evidence for behavioural disturbance of reindeer or forest ungulates under power lines. Forest ungulates could benefit from browsing in power line rights-of-way if they are managed to provide abundant and preferred forage as well as sufficient cover. However, power lines may facilitate access for hunters and predators. As a precaution, construction of power lines should be avoided in calving areas. To establish a causal relationship between the construction of power lines and potential avoidance, before-after-impact-control studies are recommended. More research is needed to make recommendations for the optimal design of power line networks.
Key words: Power lines, rights-of-way, ungulates, disturbance.