E é verdade.
Wikipedia (Brown Rat):
Alberta is unusual in that rat infestation was eliminated by aggressive government action. Although it is a major agricultural area and has a fairly high human population density, it is far from any seaport and only a portion of its eastern boundary with Saskatchewan provides a favorable entry route for rats. They cannot survive in the boreal forest to the north, the Rocky Mountains to the west, nor the semi-arid High Plains of Montana to the south. The first brown rat did not reach Alberta until 1950, and in 1951 the province launched a rat-control program that included shooting and poisoning rats, and bulldozing, burning down, and blowing up rat-infested buildings. The effort was backed by legislation that required every person and every municipality to destroy and prevent the establishment of designated pests. If they failed, the provincial government could carry out the necessary measures and charge the costs to the landowner or municipality.
In the first year of the program, 64 tonnes of arsenic trioxide was spread in 8,000 buildings (8 kg/building) on 2,700 farms along the Saskatchewan border. In 1953 the much less toxic and more effective poison Warfarin was introduced, and since then the control program has consumed between 5 and 13 tonnes of Warfarin annually. By 1960 the number of rat infestations in Alberta had dropped below 200 per year and has remained low ever since.
Currently, only zoos, universities, and research institutes are allowed to own caged rats in Alberta, and possession of an unlicensed rat (including pet rats) is punishable by a $5,000 fine or 60 days in jail. The adjacent and similarly landlocked province of Saskatchewan initiated a rat control program in 1972, and has managed to reduce the number of rats in the province substantially, although they have not been eliminated.
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