The Great Lakes and St. Lawrence River were primary attractions for early settlers to the Mixedwood Plains, and not only as a travel route. The waterways supported a tremendous wealth of fish and other aquatic species that stimulated economic growth and regional development. The Great Lakes were once dominated by large, bottom-dwelling species such as Lake Trout, Whitefish, and Sturgeon. Walleye and Largemouth Bass flourished in sheltered bays and the warm, shallow Lake Erie.
For decades aquatic communities have suffered from the effects of intense commercial fishing and habitat destruction. Many spawning and feeding areas have been lost to siltation, pollution, and dredging. Centuries of overfishing forced the Great Lakes commercial fisheries to focus primarily on introduced non-native species, such as Rainbow Smelt, White Perch, and Common Carp. Today the St. Lawrence River and its marine habitats support a diverse collection of aquatic species, including Atlantic Tomcod, Northern Pike, baleen whales and the endangered Beluga Whale.
The introduction of various exotic species is also responsible for serious economic and ecological damage. Both the Sea Lamprey and Zebra Mussel, for example, have dramatically altered aquatic ecosystems. The Zebra Mussel, aggressively spreading through most of the ecozone s waterways since 1986, has disrupted food chains by reducing phytoplankton and zooplankton populations.
Numerous bird species, including the Cardinal, Green Heron, and Carolina Wren, are unique to the Mixedwood Plains Ecozone. Typical residents of remnant forest patches and urban greenspace include Blue Jay, Whip-poor-will, Red-headed Woodpecker, and Baltimore Oriole populations. The Long Point Biosphere reserve in southern Ontario now plays a vital continental role in the protection of migratory bird habitat. Attracted to extensive marshes for staging and overwintering purposes, roughly 280 bird species have been banded in the region since 1960. For the Henslow's Sparrow, however, habitat protection has been minimal. A native to meadows and abandoned agricultural fields in southern Ontario, the sparrow was declared endangered by COSEWIC in 1993. Long-term population declines are related to intense cultivation and urban sprawl.
Two of the three reptiles listed as threatened by COSEWIC reside within the Mixedwood Plains ecozone. The eastern Massasauga Rattlesnake, commonly perceived as dangerous, is restricted to diminishing wetlands in Ontario. Stretches of the St. Lawrence River, as well as lakes St. Clair, Erie, Ontario, and Champlain, are home to the increasingly rare Spiny Softshell Turtle.
Forests and grasslands support a wide variety of terrestrial organisms in the Mixedwood Plains. Characteristic mammals include White-tailed Deer, Black Bear, eastern Cottontail, and Grey and Black Squirrels. Foxes and wolves make appearances outside urban settings, while coastal wetlands and tributaries provide crucial habitat for beaver and muskrat. Although many species have lost varying degrees of habitat to urban expansion, a handful have proved resilient. Nuisance animals, such as raccoons, house mice, and groundhogs, have found special niches within urban ecosystems and thrive there.