This species prefers generally open habitats with clumps of trees, but can also commonly be found in farmlands and suburban areas.

The species also walks or hops on the ground, where it obtains food items such as beetles, grasshoppers, worms, and small rodents.

The black-billed magpie builds domed nests which are made up of twigs and are located near the top of trees, usually housing six to seven eggs.

Black-billed magpies have a long history with humans, being featured in stories told by Indigenous tribes of the Great Plains.

Due to their perceived negative impact on cattle and game birds, black-billed magpies were hunted as a pest during the 1900s, and their population suffered as a result.

Based on the black-billed magpie's smaller size and longer tail and wing length, it was classified as the subspecies P. pica hudsonia.

The generic name Pica is the Latin word for magpie, and the specific name hudsonia is in honour of the English explorer Henry Hudson.

The name Margaret was associated with chattiness in the early 15th century, and was applied to the magpie because its vocalizations were thought to sound like a person chattering.

[6][7] In 2000, the American Ornithologists' Union recognized the black-billed magpie as a separate species, Pica hudsonia.

[8] Fossil evidence suggests that the ancestral North American magpie arrived in its current range around the mid-Pliocene, approximately 3–4 mya, having crossed the Bering land bridge.

The yellow-billed magpie lineage likely split off soon after due to the Sierra Nevada uplift and the beginning of an ice age.

[9] A comparatively low genetic difference, however, suggests that some gene flow between the black-billed and yellow-billed magpies still occurred during interglacial periods until the Pleistocene.

[3] Unlike other members of the Corvidae family, the black-billed magpie is dimorphic in size and weight, though there can be overlap between the sexes.

While the exact reason for these movements is unknown, it is thought to be a result of postbreeding dispersal and a subsequent return to their nesting sites.

[3] This species ranges from coastal southern Alaska, southwest Yukon Territory, central British Columbia, Alberta, Saskatchewan, and Manitoba in the north, through the Rocky Mountains down south to all the Rocky Mountain states including New Mexico, Colorado, Utah, Wyoming, Idaho, and some bordering states as well.

[13][14] The species is absent in California west of the Cascades and Sierra Nevada ranges, where it is replaced by the yellow-billed magpie.

[7] Nests are loose but large accumulations of branches, twigs, grass, rootlets, mud, fur, and other materials.

Biologists who have climbed nest trees to measure magpie eggs have reported that the parents recognized them personally on subsequent days and started to mob them, overlooking other people in the vicinity.

Fledging success (usually 3–4 young per nest) is lower than the typical clutch size; this is not an unusual state of affairs in species with asynchronous hatching, as some nestlings often die of starvation.

[7] The black-billed magpie is an opportunistic omnivore, eating whatever is readily available, including carrion, insects, seeds, berries, and nuts.

Black-billed magpies primarily feed on animal matter during the summer, and in the winter switch to more vegetation.

Dominance is more generally established through displays, such as stretching the body laterally with the bill raised and the nictitating membrane of the eye flashing (only on the side of the opponent).

[24] In Canada, they arrive at the roosting site earlier in the evening and leave later in the morning on colder days.

They sleep with the bill tucked under the scapular (shoulder) and back feathers, adopting this position sooner on colder nights.

[29] When Lewis and Clark first encountered black-billed magpies in 1804 in South Dakota, they reported the birds as being very bold, entering tents and taking food from the hand.

When the bison herds were devastated in the 1870s, magpies switched to cattle, and by the 1960s, they had also moved into the emerging towns and cities of the West.

[33] Because of its wide range and generally stable population, the black-billed magpie is rated as a species of least concern by the International Union for Conservation of Nature.

[34] In the United States, black-billed magpies are protected under the Migratory Bird Treaty Act, but "[a] Federal permit shall not be required to control ... [magpies] when found committing or about to commit depredations upon ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in such numbers and manner as to constitute a health hazard or other nuisance".

[37] A detriment to the overall black-billed magpie population is toxic chemicals, particularly topical pesticides applied on the backs of livestock.