We have 8 types of bats here in Minnesota. However, of the 8 only 2 infest structures. Although both are colony animals, they exhibit very different behaviors. One type of bat, the little brown bat, lives in massive colonies. The big brown bat however lives in much smaller colonies. The little brown bat is structure loyal meaning the entire colony will return to their primary hibernacula, the primary infested structure each night. With this kind of bat, the large numbers of animals coupled with their loyalty to one structure in addition to their lengthy life span has devastating consequences on the attic spaces. Piles of guano feet high and feet wide are common with the little brown bats. In addition to the massive amounts of guano, these bats urinate all over the insulation package, rafters, and other attic structure as they move about. The urine creates a gut wrenching chemical signature/odor. Big brown bats in contrast are territorial meaning any structure within its geographical territory that has openings in the roofline or eves may be infested by a cross section of the much smaller colony. Smaller colony numbers while infesting many structures all at the same time means less guano and urine being deposited in the attic and eves of each home in the colonies queue. The smaller numbers mean less damage and lessen the need for attic restoration.
