Ontario has 3 species of weasels: the short-tailed weasel, the long-tailed weasel, and the least weasel. 

Weasels have sharp, large teeth, small eyes, and small ears. Weasels colouration changes with the seasons to provide a natural camouflage, turning brown to white in the winter. 

The short-tailed weasel is found throughout North America, males range from 10.6-11.2” and females range from 8.7-10.3” in length. The long-tailed weasel males range from 13.6-17.5” and females 11-13.4” in length. Weasels life span may reach 5 or 6 years but many will die early due to natural causes. The young are born in the spring after a 9 month gestation period. They will remain with their family units until late summer. 

Weasels will build loose structured dens with tunnels connecting it the out outside. They prefer woodlands, walls, fence rows, and are usually found near a water source. They are active year long, these bold creatures are very alert, release a musk when alarmed and will stamp their feet when annoyed. 

The carnivorous mammals prey on mice, rates, voles, chipmunks, shrews, rabbits, frogs, birds, bats, insects, etc. They may eat bird eggs and will also attack poultry. Weasels are stalkers, they trace scents and will pounce. Predators of weasels include humans, cats, dogs, coyotes, large snakes, owls, foxes, large hawks and parasites contracted from infected earthworms. 
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Though weasels can be an effective mice population manager, they can become pests for farmers and their poultry.