The Slovenian Air Force recently found three of its PC-9 trainers had suffered over $7,000 of damage to their wiring when the aircraft were left outside and field mice got into them. Mice love to chew on the insulation of the wiring, and carry off bits of it for use in their nests.
This is not a new problem. German troops in Russia during World War II quickly found that, especially in the cold weather, mice would find their way into the warmer engine compartments of vehicles, and chew on things, especially the insulation of electrical wires. This would sometimes render the vehicle unusable until the damaged wires were replaced. In one spectacular case, during late 1942, dozens of German tanks (of the 22nd armored division) were rendered immobile by the mice, a fact that was only discovered when the division was called to repel a Russian attack.
Most armed forces that operate in areas with this rodent problem, have developed procedures to minimize the risk of mice disabling their vehicles and equipment. But for anyone new to the area coming in, someone either has to warn them, or they will have to learn by experience.