It is Canada's national wildlife agency, with responsibility for the protection and management of migratory birds and nationally important wildlife habitats, endangered species, research on nationally important wildlife issues, control of international trade in endangered species, and international treaties. Wildlife management in Canada is a responsibility which is shared by the federal and the provincial / territorial governments, however CWS is also responsible for Canada's "National Wildlife Areas" which are federally protected natural areas.
CWS maintains personnel and research/operations facilities in all Environment Canada regions, namely: Atlantic Region, Quebec Region, Ontario Region, Prairie and Northern Region, and Pacific and Yukon Region.
In 1916, both nations signed the "Migratory Birds Convention", followed by the Parliament of Canada passing the Migratory Birds Convention Act in 1917, which gave the federal government responsibility for managing certain migratory bird species.
Federal responsibility for the conservation of birds and terrestrial mammals was concentrated in 1947 when the precursor to CWS was formed, the Dominion Wildlife Service (DWS). By 1970 it was apparent that federal responsibility was required for further wildlife management issues, such as mammals crossing the International Boundary with the United States, as well as Canada's maritime borders with France (St. Pierre and Miquelon), Denmark (Greenland), Russia and Norway. There were also serious problems mounting whereby increasing numbers of wildlife species were threatened with extinction.
In 1973 the Canada Wildlife Act was passed, giving the federal government authority to undertake wildlife research and, in cooperation with the provinces, to undertake wildlife conservation and interpretation activities. This act applies to all "non-domestic animals" in the nation.
CWS currently holds responsibility for 140 National Wildlife Areas across the nation in a variety of environments. CWS scientific experts also advise the federal and provincial governments during environmental impact assessments for various construction and development projects which might have an adverse impact on Canadian wildlife.