The gray-faced buzzard was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[2] Gmelin based his account on the "Javan hawk" that had been described in 1781 by John Latham from a specimen in the Leverian collection that had been obtained in February 1780 at Princes Island off the westernmost cape of Java during Captain Cook's last voyage.

[3][4] The gray-faced buzzard in now one of four species placed in the genus Butastur that was introduced in 1843 by the English naturalist Brian Houghton Hodgson.

Wind support and geographic features (i.e. islands) enable the birds to migrate in an oceanic flyway.

Grey faced buzzards set out on their autumn migration and head south in flocks from late September to mid-October.

As with most buzzards, these birds utilize rising air currents to gain altitude and cover great distances by soaring during migration.

Taiwan lies on a major migration route for the grey faced buzzard, and large numbers may be seen moving southward in October along the Hengchun Peninsula, and northward in late March and early April along the terraced mountains of Taichung and Changhua.

They perch on a tree or a utility pole adjacent to an open habitat, such as rice fields, cropland, and clearings, and swoop down to capture with their feet small animals occurring in Satoyama.

A variety of prey including frogs, small mammals, lizards, snakes and insects were taken at levees and grass-arable fields.

Fledglings are fed by the parent birds around the nest for about two weeks, and then become independent, starting to move a long distance.

[9] Historically, the greatest threat to the grey-faced buzzard in Taiwan has been the uncontrolled hunting of the species in the Baguashan and Hengchun Peninsula areas.

A basic plan for "Creating a wood Grey-faced buzzards can live" by Toyota City of Aichi Pref.

In the Toyota natural Observation Woods, which contain a Satoyama Landscape with Yatsuda, Toyota City has taken the initiative in creating the habitat of frogs grey-faced buzzards prey on and maintaining their foraging grounds by weeding and water management of private fallow rice fields.