Biting insects can be bothersome during warm weather. Parasitic deer ticks (which are known to carry Lyme disease) are a potential hazard. The trail passes through black bear habitat, although problems with bears are rare. More likely are problem encounters with domestic dogs. Skunks, raccoons, and porcupines are common and active after dark. Poisonous snakes are considered extinct along the route. Poison ivy is uncommon on the MSGT and it does not thrive on Mount Monadnock at all. Some water sources along the trail flow through inhabited areas or swamps and may be contaminated.