The core responsibility of the Canadian Wildlife Service are the protection and management of migratory birds, species at risk, and their nationally important habitats.

Functions of the Canadian Wildlife Service include scientific, regulatory, property management, policy, and financial support work.

Scientific monitoring of migratory bird and species at risk population sizes and distribution, wetlands and critical habitats occurs throughout Canada.

Wildlife research is predominantly waterfowl and seabird population ecology and toxicology, with a few scientists addressing reptiles, polar bears, and caribou.

[citation needed] CWS traces its history to the early 20th century with the decline and/or extinction of several species of migratory birds in eastern North America as a result of hunting, including the passenger pigeon.

Like trees, birds, mammals, and fish were generally viewed a resources to be responsibly managed for the purpose of generating long-terms economic returns."

Significant growth of the organization occurred during this period, and CWS began providing broader wildlife research and management services to National Parks.

Tony Keith, director of the National Wildlife Research Centre from 1976 to 1996, presented his work on PCBs and the environment to the Organisation for Economic Co-operation and Development (OECD).

David B. Peakall contributed to the OECD's adoption of "Minimum Pre-market Data" criteria regarding common standards for regulation and approval of new pesticides.

In 1976 the Committee on the Status of Endangered Wildlife in Canada brought together experts in all taxa from across the country and began preparing lists of species at risk using criteria consistent with the International Union for the Conservation of Nature.

The Fisheries Act (1986) transferred some responsibilities for aquatic ecosystem research to the Department of Fisheries and Oceans, but Canadian Wildlife Service also retracted from servicing the National Parks, cut caribou research in the Arctic, several interpretive centers opened in the early 1980s were closed by the late 1980s, and growth of the National Wildlife Areas and Migratory Bird Sanctuaries effectively ended during this period of time.

Attempts were made to eliminate the name "Canadian Wildlife Service" to something that reflected a broader role in biodiversity conservation, and the logo of the Loon adopted in the early 1980s was banned for use in official communications.

The changes were ushered in following a dramatic shift in human and financial resources away from migratory bird research and management to the administration and implementation of the Species at Risk Act.