Electrical Problems Caused by the Brown Treesnake
Brown Treesnakes are commonly encountered climbing on man-made structures. Since they can lift three-fourths of their body using the remaining quarter for support, even small cracks and imperfections in surfaces are enough to give them leverage. Power lines, wooden poles, and guy wires are no greater challenge for these snakes than a tree or exterior wall of a building. Snakes often cause problems by climbing guy wires leading to power poles supporting transformers, distribution lines, and high-voltage transmission lines. When the snakes simultaneously touch live and grounded conductors, they create faults, short circuits, and electrical damages. This results in frequent losses of power to parts of Guam and even island-wide blackouts. Such power failures, brownouts, and electrical surges, occurring on average approximately one every three days, damage electrical appliances and interrupt all activities dependent on electrical power, including commerce, banking, air transportation, and medical services. Power outages caused by snakes have been a serious problem on Guam since 1978, and the incidence of snake-caused outages continues to cause significant problems. Records show that more than 1,600 snake-caused outages occurred from 1978-1997.
Although precise cost figures are unavailable, it is conservatively estimated that these power outages cost several million dollars each year. Costs include: damage to electrical distribution equipment; increased maintenance and emergency repair crews during nighttime; loss of revenues during outages; damage to equipment of electrical consumers due to voltage drops, surges, and repeated outages; increased need for backup generators and transformers to protect against surges; and loss of goods and business by consumers during outages. These figures add up to a big problem for the utility companies and Guam's 100,000 inhabitants.
Attempts to control this problem include turning off one utility line identified as a major source of snake-caused faults. Since 1985, this line has been shut down from dusk to dawn, the hours when the snakes are most active. Snakes are so abundant in this area that snake traps placed on guy wires captured nearly as many snakes as similar traps placed in heavily forested areas. Alternately, an effort to exclude snakes from one principal transmission line on Guam with large disk barriers on guy wires and stainless steel flashing on poles was successful in reducing but not eliminating outages on that line. Snakes are still able to gain access to conductors by climbing on guy wires, wooden poles, and adjacent vegetation.
Current suggestions for control of snake-caused outages are threefold. The first is the recommended elimination of guy wires. Snakes are much more adept at climbing guy wires than the sheer vertical surfaces of concrete poles, as proven by behavioral studies and the low incidence of snakes on poles without guy wires. In areas where it is impossible or not economical to eliminate guy wires, they can be lowered to prevent snakes from reaching conductors. And finally, barriers can be used on existing guy wires accompanied by careful placement of extra wires and regular trimming of nearby vegetation to further prevent snakes from gaining access.
Guam has 23 major power distribution circuits run by the U.S. Navy and the Guam Power Authority (GPA). This compartmentalization of the electrical system reduces the chances of outages affecting the entire island or major geographic areas. However, major outages still occur. Many smaller Pacific Islands have fewer generating facilities and circuits, and if the snake becomes abundant on these islands, the damage to their electrical systems is more likely to affect the entire island or major municipal areas. Even Oahu, with a population of about 1 million, is subject to island-wide outages. One such outage caused by an electrical fire in an underground substation cost the island an estimated $20-60 million. Many Pacific Islands suffer power supply problems, but the frequency and severity of the outages on Guam would be devastating to an island with fewer alternate distribution lines and with less ability to shift to other generating facilities.