Old World harriers include:
- Spotted harrier (Circus assimilis). Found throughout most of Australia, and sometimes in Tasmania.
- European marsh harrier (Circus ranivorus). Resident of northern Kenya, Uganda, eastern Zaire, and Angola.
- Marsh harrier (Circus aeruginosus). Resident of western Europe, central Asia, and Japan; winters in Africa and southern Asia.
- Black harrier (Circus maurus). Resident of southern Africa.
Harriers in North America and their status are as follows:
- Northern harrier (Circus cyaneus). Has disappeared from many of its former nesting areas. Decline attributed to loss of habitat and effects of pesticides. In 1970, 20% of the eggs examined were found to exhibit shell thinning. Today the population appears to be declining in parts of North America.