Intrusion by animals into electric supply substations has been a problem experienced by most of the electric utility industry . The costs associated with outages caused by animals continue to escalate. Although animal problems differ in nature geographically, the damage to equipment, interruption of or loss of service to customers, and safety problems encountered by operating personnel result in the same general concerns. This guide identifies various animals, the problems they cause and mitigation methods. Further, it recommends criteria for applying mitigation methods, documents survey-reported effectiveness of various methods and recommends factors for evaluating effectiveness of methods once they are applied.