Wildlife of
Ontario

Primary Threats

• Highest in southern Ontario where wetlands, tallgrass prairie, and Carolinian forest remnants have been converted or isolated by development and agriculture. Along the Great Lakes, shoreline hardening, marinas, and cottage development reduce coastal wetland function that supports spawning fish, amphibians, and migratory waterfowl.
• Rapid growth in the Greater Golden Horseshoe (GTA-Hamilton-Niagara-Kitchener-Waterloo corridor) increases habitat fragmentation, road mortality, stormwater impacts to creeks, and pressure on ravines, kettle lakes, and wetlands. Urban expansion also stresses species at risk that depend on remaining sand barrens, alvars, and meadow complexes.
• Row-crop agriculture in southwestern and eastern Ontario drives drainage/alteration of wetlands and headwater streams, increases pesticide exposure, and contributes nutrient and sediment runoff to Lake Erie and Lake Ontario nearshore zones-affecting aquatic food webs and water quality.
• Nutrient loading (notably phosphorus) and sediment from watersheds contribute to harmful algal blooms and hypoxia, especially in western Lake Erie and some inland lakes. Legacy contaminants (e.g., PCBs, mercury) persist in parts of the Great Lakes and some northern watersheds, affecting fish consumption advisories and wildlife health.
• Great Lakes invaders (zebra/quagga mussels, round goby, sea lamprey, spiny water flea) alter food webs and native fish recruitment. On land, invasive Phragmites degrades coastal marshes (e.g., Lake Erie and Lake Huron shorelines), and forest pests like emerald ash borer reshape riparian and urban forests.
• Warming winters reduce ice cover on the Great Lakes, intensifying shoreline erosion and altering nearshore ecology; warmer waters stress coldwater fisheries (brook trout, lake trout in some inland systems). In the north, changing fire regimes, thawing peatlands, and shifting insect outbreaks affect boreal habitat stability and carbon storage.
• In the boreal forest, intensive harvest patterns and associated access can fragment mature conifer habitats and increase predator-prey imbalances, contributing to declines of forest-dwelling woodland caribou. Cumulative effects are amplified where forestry overlaps with roads, energy corridors, and settlements.
• Mining proposals and development (including in remote northern regions such as the Ring of Fire area) can create new roads, habitat fragmentation, and risks to sensitive peatlands and headwaters. Legacy mine sites and tailings can contribute localized metal contamination without strong remediation.
• Road networks, hydro corridors, and expanding access in northern Ontario increase linear disturbance that facilitates predators and human access into intact habitats. In the south, roads are a major mortality source for turtles and snakes, and barriers/culverts fragment aquatic habitats.
• Altered hydrology from drainage, channelization, dams, and water-level regulation affects wetlands and riverine habitats. Fire suppression in parts of the province can reduce early-successional and open-forest structures important for some birds and plants, while water control structures change spawning/nursery habitats for fish.
• Although many Great Lakes fisheries are tightly managed, localized overharvest risk persists for some populations and species (e.g., sensitive sturgeon populations and some inland lake fisheries) through combined recreational pressure, bycatch, and habitat constraints.
• Regulated hunting is a major management lever; however, in some regions harvest must be carefully balanced with population stressors (e.g., moose affected by parasites and climate, or localized pressures on waterfowl staging areas). Illegal take can be significant for some reptiles.
• Illegal collection and trade of Ontario reptiles-especially turtles (e.g., Blanding's, spotted, and other species)-remains a documented threat, compounded by their slow life histories and road mortality.
• White-nose syndrome has caused major declines in hibernating bats (little brown myotis, northern myotis, tri-colored bat). Additional concerns include ranavirus/chytrid impacts on amphibians and ongoing surveillance/preparedness for chronic wasting disease to protect cervid populations.
• High visitation at dunes and beaches (e.g., Lake Erie and Lake Huron shorelines) can disrupt nesting of beach-dependent birds and trample dune vegetation. Boating/wakes and nearshore recreation can degrade sensitive coastal wetlands and disturb colonial waterbirds.
• In southern and near-northern communities, conflicts with black bears, coyotes, deer, and Canada geese drive calls for lethal control and can reduce public tolerance for wildlife. In some northern areas, expanded access increases interactions that affect sensitive species and enforcement capacity.
• Small, isolated subpopulations-especially of turtles in fragmented southern landscapes and woodland caribou in the southern edge of their range-face reduced connectivity and potential loss of genetic diversity, increasing long-term extinction risk.
• Localized water withdrawals and groundwater use (e.g., in rapidly growing municipalities and some agricultural regions) can reduce baseflows and stress coldwater streams, wetlands, and dependent species during drought periods.