The black-billed magpie (Pica hudsonia), also known as the American magpie, is a bird in the corvid family found in the western half of North America. It is black and white, with the wings and tail showing black areas and iridescent hints of blue and blue-green. It was formerly treated as a subspecies of Pica pica (Eurasian magpie), but was separated as a species in its own in 2000 based on genetic studies.
This species prefers generally open habitats with clumps of trees, but can also commonly be found in farmlands and suburban areas. Historically associated with bison herds, it now lands on the backs of cattle to glean ticks and insects from them. Black-billed magpies commonly follow large predators, such as wolves, to scavenge from their kills. 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. Incubation, by the female only, starts when the clutch is complete, and lasts 16–21 days. The nestling period is three to four weeks. Black-billed magpies in the wild have a lifespan of six to seven years.
Black-billed magpies have a long history with humans, being featured in stories told by Indigenous tribes of the Great Plains. Where persecuted it becomes very wary, but otherwise it is fairly tolerant of human presence. 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. Today, they are considered a species of least concern by the IUCN, and they are commonly seen throughout their range.
Taxonomy and systematics
thumb|left|On the [[Yellowhead Highway near Jasper, Alberta ]]
The black-billed magpie was originally described in 1823 as "Corvus Hudsonius, Hudson's Bay Magpie" by Joseph Sabine in his report of an expedition to the North American Arctic. In previous encounters with the bird prior to its formal description, it had been presumed to be of the same bird as the magpies from Europe; Sabine wrote of it: The generic name Pica is the Latin word for magpie, and the specific name hudsonia is from the Hudson Bay, where it was first distinguished as distinct.
The American Ornithologists' Union (AOU) 1880 first checklist of American birds called it "American magpie", but in the 1957 fifth edition it was renamed to "black-billed magpie", without explanation but presumably as a distinguishing counterpoint to the related yellow-billed magpie. In this edition, the AOU applied the name "black-billed magpie" to the whole of Pica pica, though this name had no history of use in the species' main range in Europe.
The black-billed magpie was then widely considered conspecific with the Eurasian magpie until mtDNA studies showed a relatively high divergence between the two species. It was also shown that the black-billed magpie was more closely related to California's yellow-billed magpie (Pica nuttalli) than it was to Eurasian magpies. Black-billed magpies are also shown to have different social behaviour and vocalizations from the Eurasian magpie, further indicating separate species.
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. From there, the Eurasian and North American populations began to differentiate. The yellow-billed magpie lineage likely split off soon after due to the Sierra Nevada uplift and the beginning of an ice age.
Unlike most other members of the family Corvidae, the black-billed magpie is dimorphic in size and weight, though there can be overlap between the sexes. Males are, on average, 6–9% larger and 16–24% heavier than females, at , an individual wing chord of , and tail lengths of . Females weigh between , have individual wing chords of , and tail lengths of .
thumb|right|A juvenile with grey [[iris (anatomy)|irises and slightly visible pink mouth-lining|alt=A juvenile black-billed magpie in profile]]
Juveniles have less iridescence on their wings and tail, buffier scapulars and belly, and they lack the distinctive long tail feathers. Their rectrices are typically rounder and narrower, and have more black on their wing-tips compared to mature adults.
Distribution and habitat
Black-billed magpies are generally non-migratory, however some winter movement does occur. 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.
If regularly disturbed, black-billed magpie pairs will aggressively defend their nest. If the disturbances continue, they will eventually either move the eggs or abandon the clutch altogether. 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.
Black-billed magpies generally start breeding in late March, with the breeding season ending in early July. While they typically only nest once per year, a second nesting may take place if the initial nesting fails early. The average clutch size is six or seven eggs, however females may lay up to thirteen eggs.
thumb|left|Eating insects off the back of a cow
Black-billed magpies are also known to make food caches in the ground, in scatter-hoarding fashion. Flight is commonly interrupted by nonflapping phases. Descents from heights consist of repeated J-shaped swoops with the wings nearly closed.
Conservation status
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. The global population was estimated to be 6,000,000 mature individuals in 2025.
In Canada, however, the black-billed magpie does not appear on the list of birds protected by the Migratory Birds Convention Act. Provincial laws also apply, but in Alberta, magpies may be hunted and trapped without a license.
A detriment to the overall black-billed magpie population is toxic chemicals, particularly topical pesticides applied on the backs of livestock. Because black-billed magpies sometimes glean ticks off the backs of cattle, this proves a problem. However, in some areas, it has benefited from forest fragmentation and agricultural developments.
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Further reading
- Washington Department of Fish and Wildlife, Living with Wildlife; Facts about Magpies
- Black-billed magpie species account—Cornell Lab of Ornithology
- Black-billed magpie—Birds of the world