Nesting Instinct
South American ovenbirds build cozy cavelike nests using mud, grass, and bark. Elaborate home-building behaviors, which are seen in all 240 ovenbird species, appear to be innate, or unlearned (Wuethrich, 1999, November 29). Their architectural aptitude seems to be the result of instinct.

Fritz Poelking/Age Fotostock