Indianapolis is situated in the Southern Great Lakes forests ecoregion which in turn is located within the larger temperate broadleaf and mixed forests biome, as defined by the World Wide Fund for Nature.[89] Based on the United States Environmental Protection Agency's alternative classification system, the city is located in the Eastern Corn Belt Plains, an area of the U.S. known for its fertile agricultural land.[90]
Much of the decidious forests that once covered 98% of the region were cleared for agriculture and urban development, contributing to considerable habitat loss.[89][87] Indianapolis's current urban tree canopy averages approximately 33%.[91] A rare example of old-growth forest in the city can be found on 15 acres (6.1 ha) of Crown Hill Cemetery's North Woods in the Butler–Tarkington neighborhood.[92] The cemetery's 555 acres (225 ha) represents the largest green space in Center Township, home to an abundance of wildlife and some 130 species of trees.[93] Native trees most common to the area include varieties of ash, maple, and oak.[89] Several invasive species are also common in Indianapolis, including tree of heaven, wintercreeper, Amur honeysuckle, and Callery or Bradford pear.[94][95]
A 2016 bioblitz along three of the city's riparian corridors found 590 taxa.[87] Urban wildlife common to the Indianapolis area include mammals such as the white-tailed deer, eastern chipmunk, eastern cottontail, and the eastern grey and American red squirrels.[89] In recent years, local raccoon and groundhog populations have increased alongside sightings of American badgers, beavers, mink, coyotes, and red fox.[96][97] Birds native to the area include the northern cardinal, wood thrush, eastern screech owl, mourning dove, pileated and red-bellied woodpeckers, and wild turkey.[89] Located in the Mississippi Flyway, the city sees more than 400 migratory bird species throughout the year.[98][99][100] Some 57 species of fish can be found in the city's waterways, including bass and sunfish.[88] Some federally-designated endangered and threatened species are native to the Indianapolis area, including several species of freshwater mussels, the rusty patched bumble bee, Indiana bat, northern long-eared bat, and the running buffalo clover.[101]
In recent years, the National Wildlife Federation has ranked Indianapolis among the ten most wildlife-friendly cities in the U.S.