Squirrels are generally intelligent and persistent animals. In residential neighborhoods, they are notorious for discovering clever methods to circumvent obstacles in order to eat out of bird feeders. Tree squirrels also create minor annoyances by digging in planting pots and flower beds to pull out bulbs which they chew on, to either bury or recover seeds and nuts, and for building nests within human domiciles, including attics and basements. Squirrels use their keen sense of smell to locate buried nuts and can dig extensive holes in the process.
Although they are expert climbers, and primarily arboreal, squirrels also thrive in urban environments, where they have adapted to humans.
Squirrels are sometimes considered pests because of their propensity to chew on various edible and inedible objects. This characteristic trait aids in maintaining sharp teeth, and because their teeth grow continuously, prevents over-growth. Squirrels are often the cause of power outages. They can readily climb a power pole and crawl across a power line. The animals will climb onto transformers or capacitors looking for food. If they touch a high voltage conductor and a grounded portion of the device at the same time, they are then electrocuted and cause a short circuit that shuts down equipment. Squirrels have brought down the high-tech NASDAQ stock market twice and were responsible for a spate of power outages at the University of Alabama. To sharpen their teeth they will often chew on tree branches or even the occasional live power line. Rubber plates (squirrel guards) are sometimes used to prevent access to these facilities.
A decline of the red squirrel and the rise of the eastern gray squirrel has been noticed in Calgary.