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The population of yellow-billed magpies has been decimated since West Nile virus became established in California in 2004. As West Nile virus becomes prevalent in more northerly ranges, this may become an issue for closely related black-billed magpies.
Two different alarm calls have been described: a basic alarm and a staccato alarm. The basic alarm is a harsh rattling, which can vary in volume and speed of call depending on the danger, and may serve to incite mobbing behaviour. The staccato alarm is quicker, more excited and may represent the signal to flee from a more dangerous predator. A wide range of vocalizations has been documented in European magpies, more research is needed in North American species. Like other members of the corvid family, black-billed magpies are highly intelligent birds. When kept captive from a young age, black-billed magpies can be taught to speak a number of words and phrases.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
During the first half of the 1900’s, black-billed magpies were widely treated as pests due to their use of food crops, poultry, and livestock as part of their diet. Although determined efforts are still made to control magpie populations in certain agricultural areas, they are generally common throughout their range. Black-billed magpies are fully protected in the U.S. under the Migratory Bird Treaty Act but currently receive no protection in Canada.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Black-billed magpies occasionally cause damage to fruit and nut crops, especially if other food sources are in decline and they are aggregated in larger flocks. Black-billed magpies will eat the eggs and hatchlings of chickens and can have a negative effect on poultry production. They also gather in areas with livestock to eat the insects living in dung and to scavenge from dead or dying animals. Black-billed magpies have gained some notoriety by picking insects out of open wounds on the backs of livestock, which may eventually kill some animals due to infection, or by eating the eyes of new-born animals. Due to these negative effects on crops, livestock, and poultry, various anti-magpie techniques have been employed by agricultural producers, such as netting, frightening devices, and live trapping.
Negative Impacts: crop pest
Black-billed magpies eat pest species such as grasshoppers, cutworms (Agrotis larvae), and wireworm (Elateridae larvae), and can benefit agricultural areas by keeping down populations of these insects. When their natural foods are in abundance, black-billed magpies will not feed on food crops and livestock.
Positive Impacts: controls pest population
The sturdy nests built by black-billed magpies may last four years or more and are often reused by other birds. Owls and ducks may build their own nests on top or use the domed nest for shelter during the winter. Black-billed magpies have a symbiotic relationship with large ungulates such as deer, from which they sometimes eat ticks.
Fly maggots and wood ticks (Permacentor) will suck the blood of nestlings. Black-billed magpies may have many internal parasites such as roundworms (Nematoda), tapeworms (Cestoda), and flukes (Trematoda). These internal parasites may be due to their broad diet.
Mutualist Species:
Commensal/Parasitic Species:
Black-billed magpies, like other corvids, are opportunistic omnivores. They often forage for food on the ground and their diet can partially be determined by the small pellet that they regurgitate soon after eating. They primarily eat insects and their larva, as well as the eggs and hatchlings of songbirds. They also eat fruit and grain crops and small mammals like mice and meadow voles. Black-billed magpies scavenge for carrion and are often seen along roadsides picking at roadkill and human refuse. Black-billed magpies dig small depressions in the ground or the snow to store food.
Animal Foods: birds; mammals; eggs; carrion ; insects; terrestrial non-insect arthropods
Plant Foods: seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: omnivore
Black-billed magpies are found in western North America, with a range extending from northwestern Alaska through the prairie provinces of Canada to southern Manitoba, and south to northern Arizona, New Mexico, and western Texas. The boundaries of this range overlap with a region characterized by a cold, semi-arid, steppe climate. Black-billed magpie distribution may be limited by summer heat in the desert regions to the south, humidity to the east, and dense boreal forest to the north.
Biogeographic Regions: nearctic (Native )
Black-billed magpies inhabit rangeland and wooded country with open fields, usually close to water. Wooded areas and shrubby thickets are needed for nesting and as a means of escape if pursued, whereas meadows and clearings are used for foraging. The other habitat requirement is trees and shrubs that are strong enough to support their relatively bulky nests. These conditions are usually met in edge and riparian habitats. Farm sites and agricultural areas have these same qualities, which make rural human settlements ideal habitat. Refuse in agricultural areas also provide scavenging opportunities, such as open compost piles.
Black-billed magpies are found at elevations up to 3000 meters and are considered non-migratory, although post-breeding movements and winter movements do occur. Some populations move to different elevations or areas after breeding. Distances of several hundred kilometers may be covered in this period, sometimes these movements are made in large groups.
Range elevation: 3000 (high) m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Other Habitat Features: agricultural ; riparian
The average lifespan of male black-billed magpies is 3.5 years, females live on average 2 years, although these numbers may represent relatively high levels of mortality of the young, with average ages being higher when first year mortality is not considered. The oldest banded bird was 15 years and one month old. The longest known lifespan in captivity is 20 years.
Range lifespan
Status: wild: 15 (high) years.
Range lifespan
Status: captivity: 20 (high) years.
Typical lifespan
Status: wild: 2.0 to 3.5 years.
Black-billed magpies are mid-sized birds with a long tail, represent up to half of their length. They range in size from 45 to 60 cm long, with a wingspan of 56 to 61 cm. Black-billed magpies weigh between 145 and 210 g. The head, upper breast, back, and tail are black. There are large patches of white on the wings and lower breast. They have heavy black bills and black legs. At a distance, black-billed magpies are mainly black and white but have colorful iridescent patches ranging from bronze to green on the tail, body, and wings. Sexes are similar in coloration, but females are about 10% smaller in size than males.
Black-billed magpies and yellow-billed magpies (Pica nuttalli) are the only two magpie species in North America. They are easily distinguished by the color of the bill and breeding range since yellow-billed magpies are found only in California. Black-billed magpies of North America were formerly considered a subspecies of Pica pica, but mtDNA evidence suggests that the two North American magpie species are more closely related and may share a common ancestor.
Range mass: 145 to 210 g.
Range length: 45 to 60 cm.
Range wingspan: 56 to 61 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; male larger
Known predators of black-billed magpies include American crows (Corvus brachyrhynchos), common ravens (Corvus corax), great horned owls (Bubo virginianus), northern harriers (Circus cyaneus), red-tailed hawks (Buteo jamaicensis), Swainson’s hawks (Buteo swainsoni), weasels (Mustela), mink (Neovison vison), domestic cats (Felis catus), raccoons (Procyon lotor), coyotes (Canis latrans), and red squirrels (Tamiasciurus hudsonicus). Mammalian predators and American crows are most likely to eat eggs or young nestlings. Birds of prey and common ravens are the biggest threats to fledgling birds. Black-billed magpies may roost in dense thickets and coniferous trees as an adaptation against great horned owl predation. The dome above the nest may act as protection from great horned owls and common ravens.
Groups of adult and juvenile birds cooperate in mobbing predators. This group behavior is usually effective in causing the predator to abandon the hunt. Black-billed magpies have different mobbing responses to predators that are most likely to attack at that particular stage. Although functioning as a defense mechanism, mobbing may also serve as an effective learning method to teach the young which animals are more dangerous and warrant a longer and more vigorous alarm call.
Known Predators:
Black-billed magpies form monogamous pairs throughout the breeding season and may form lifelong bonds. In some regions black-billed magpies switch mates almost yearly. Courtship displays involve the male flashing his wings and flaring his tail at the female. Females will call loudly during their fertile period. Males respond by courtship-feeding of females. These behaviors continue from mating to incubation of the eggs. Since other males may be attracted by the loud calls of the fertile female, males vigilantly guard their mates to prevent extra-pair copulations.
Mating System: monogamous
Black-billed magpies breed from late March to early June, depending on location. There is usually one brood per season, although a second brood may be attempted if the first is not successful. Females lay up to 9 eggs (average of 6) which are greenish-gray with brown markings. The eggs are 3.3 by 2.3 cm and are sub-elliptical to oval. The first egg hatches within 25 days of being laid, hatching is asynchronous with usually only one chick hatching per day. The chicks are born without feathers and the eyes remain closed for 7 days. Fledging takes place between 24 to 30 days after hatching. The parents feed the chicks in or near the nest for the first 3 to 4 weeks and the young are beginning to fend for themselves by weeks 6 to 8. Young become independent at about 70 days. Females are likely to nest in their first year, whereas males may not breed until their second or third year.
Breeding interval: Black-billed magpies produce one brood yearly.
Breeding season: Black-billed magpies breed from late March to early June.
Range eggs per season: 9 (high) .
Average eggs per season: 6.
Range time to hatching: 25 (high) days.
Average fledging age: 27.5 days.
Range time to independence: 70 (high) days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Both sexes help to construct an elaborate, domed nest which may take between 5 and 7 weeks to complete. Males focus on building the 60 to 120 cm high dome, while females focus on the egg bowl, which is a mud cup lined with hair, grasses, bark strips, fibrous roots, and feathers. The female is the primary defender of the nest prior to and during egg laying, and males become the defender of the nest during incubation. Like other members of the corvid family, the female is the sole incubator and is almost totally reliant on the male to feed her during this period. Because the sexes have specialized roles, if either mate dies during incubation, the brood does not survive. Both male and female help to gather food for the nestlings after hatching. The female is presumed to eat the fecal sacs of the young. The post-fledging period, during which parents continue to feed their young, is much longer than in crows. This period may be instrumental in teaching the young how to recognize danger and what the most appropriate response is for a particular predator.
Parental Investment: altricial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Male, Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female); post-independence association with parents; extended period of juvenile learning
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 black areas on the wings and tail showing iridescent hints of blue or blue-green. It is one of only four North American songbirds whose tail makes up half or more of the total body length (the others being the yellow-billed magpie, the scissor-tailed flycatcher, and the fork-tailed flycatcher).
This species prefers generally open habitats with clumps of trees. It can therefore be found in farmlands and suburban areas, where it comes into regular contact with people. Where persecuted it becomes very wary, but otherwise it is fairly tolerant of human presence. Historically associated with bison herds, it now lands on the backs of cattle to glean ticks and insects from them. Large predators such as wolves are commonly followed by black-billed magpies, who 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 is one of the few North American birds that build a domed nest, which is made up of twigs and sits near the top of trees, usually housing 6–7 eggs. Incubation, by the female only, starts when the clutch is complete, and lasts 16–21 days. The nestling period is 3–4 weeks.
Externally, the black-billed magpie is almost identical to the Eurasian magpie (Pica pica), and is considered conspecific by many sources. The American Ornithologists' Union, however, splits it as a separate species (P. hudsonia), on the grounds that its mtDNA sequence is closer to that of California's yellow-billed magpie (Pica nuttalli) than to the Eurasian magpie. If this view is correct, the Korean subspecies of the European magpie, Pica pica sericea, should also be considered a separate species.[2]
It appears that after the ancestral magpie spread over Eurasia, the Korean population became isolated, at which point the species crossed the Bering Land Bridge and colonized North America, where the two American magpies then differentiated. Fossil evidence indicates that the ancestral North American magpie had arrived in its current range around the mid-Pliocene (3–4 mya) and that the yellow-billed magpie lineage split off rather soon thereafter due to the Sierra Nevada uplift and the beginning ice ages.[3] 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.
The black-billed magpie is a mid-sized bird that measures 45–60 centimeters (18–24 in) from tip to tail. The tail is made up of long, layered feathers, the middle pair of which protrude farthest of all. The beak is oblong and weakly curved toward the tip. 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. Males are, on average, six to nine percent larger and sixteen to twenty-four percent heavier than females, at 167–216 grams (5.9–7.6 oz), a wingspan of 205–219 millimeters (8.1–8.6 in), and tail lengths of 230–320 millimeters (9.1–12.6 in). Females weigh between 141–179 grams (5.0–6.3 oz), have wingspans of 175–210 millimeters (6.9–8.3 in), and tail lengths of 232–300 millimeters (9.1–11.8 in).[4]
The black-billed magpie can be distinguished from the similar yellow-billed magpie by its longer tail and by the colour of the beak.
The vocalizations of the black-billed magpie consist of a number of calls variously described as tweets, coos, purrs, shrills and squawks, but the most common is an alarm call, called a chatter, and described as a ka-ka-ka-ka, sometimes preceded with a skah-skah.[4] This call is very different from that of the Eurasian magpie, and is similar to that of the yellow-billed magpie.[5]: 185 At least one Black-billed, living with humans, has learnt to imitate human speech.[6]
The species is non-migratory. It 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. The range can extend as far east as northern Minnesota and Iowa, with casual records in northern Wisconsin and upper Michigan, but is thought to be limited further east and south by high temperature and humidity.[7][8] The species is absent in California west of the Cascades and Sierra Nevada ranges, where it is replaced by the yellow-billed magpie.
During the breeding season the preferred habitat is riparian areas with thickets. The predilection for open habitats with clumps of trees means that the species also breeds in some meadows and suburbs. Outside the breeding season, magpies can be found in their breeding habitat but also near feedlots, grain elevators, landfills, and around barns and houses.
Adult black-billed magpie pairs stay together year-round and often for life unless one dies, in which case the remaining magpie may find another mate. Divorces are possible: one South Dakota study found low rates of divorce (8%)[9] but one 7-year study in Alberta found divorce rates up to 63%.[10]
Black-billed magpies nest individually, frequently toward the top of trees. Only the nest tree and its immediate surroundings are defended, and so it is possible for nests to be somewhat clumped in a location. When this happens (usually in areas with a limited number of trees or with abundant food resources), a diffuse colony is formed. In this, the black-billed magpie is intermediate between the Eurasian magpie, whose nests are much more spread out because a large territory is defended around each nest, and the yellow-billed magpie, which is always loosely colonial.
Nests are loose but large accumulations of branches, twigs, grass, rootlets, bark strips, vines, needles, and other materials, with branches and twigs constituting the base and framework, while mud is used as anchor and in the nest cup. The nest cup is lined with fine rootlets, grass, and other soft material. Nests almost always include a hood or dome of loosely assembled twigs and branches, and usually have one or more side entrances. Nests are built by both sexes over 40–50 days, starting in February (though later in northern parts of the range). Old nests can be repaired and used, or a new nest can be built on top, with older nests thus reaching 120 cm high by 100 cm wide (48 inches high by 40 inches wide). Other bird species, including small hawks and owls, often use old magpie nests.
The breeding season for magpies is generally from late March to early July. They nest once a year, but may re-nest if their first attempt fails early. The female lays up to thirteen eggs, but the usual clutch size is six or seven. The eggs are greenish grey, marked with browns, and 33 mm (about 1.3 inch) long. Only the female incubates, for 16–21 days. The male feeds the female throughout incubation. Hatching is often asynchronous. Hatched young are altricial, brooded by the female but fed by both sexes. They fly 3–4 weeks after hatching, feed with adults for about two months, and then fly off to join other juvenile magpies. Fledging success (usually 3–4 young per nest) is lower than clutch size; this is not an unusual state of affairs in species with asynchronous hatching, as some nestlings often die of starvation.
Black-billed magpies reach sexual maturity at one or two years of age. The lifespan of the species in the wild is about four to six years.
The black-billed magpie is an opportunistic omnivore, eating many types of insects, carrion, seeds, rodents, berries, nuts, eggs, and also garbage and food from pets that are fed outside. Chicks are fed animal matter almost exclusively. Magpies typically forage on the ground, usually walking, sometimes hopping, and sometimes scratching with their feet to turn over ground litter. They sometimes land on large mammals, such as moose or cattle, to pick at the ticks that often plague these animals. They often follow large predators, such as wolves, to scavenge or steal from their kills.
Black-billed magpies are also known to make food caches in the ground, in scatter-hoarding fashion.[11] To make a cache, the bird pushes or hammers its bill into the ground (or snow), forming a small hole into which it deposits the food items it was holding in a small pouch under its tongue. It may, however, then move the food to another location, particularly if other magpies are in the vicinity, watching. Cache robbing is fairly common, so a magpie often makes several false caches before a real one. The final cache is covered with grass, leaves, or twigs. After this, the bird cocks its head and stares at the cache, possibly to commit the site to memory. Such hoards are short-term; the food is usually recovered within several days, or the bird never returns. The bird relocates its caches by sight and also by smell; during cache robbing, smell is probably the primary cue.[12]
Black-billed magpies often form loose flocks outside of the breeding season. Dominance hierarchies typically develop within such flocks, more linearly among males than among females. Dominants can steal food from subordinates. Aggressive interactions also occur at point sources of food. Surprisingly, young males appear dominant over adult males, though this may simply reflect the adults' better overall condition and consequent lack of motivation to engage in fights.[13] [14] Fights are rare and involve jumps and kicks. 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).[4]
Magpies often gather excitedly in trees near the body of a dead magpie, calling loudly, a poorly-understood behaviour called a funeral.[11] Some individuals may approach the body and peck at its wings or tail.
Magpies tend to roost communally in winter. Every evening they fly, often in groups and sometimes over long distances, to reach safe roosting sites such as dense trees or shrubs that impede predator movement, or, at higher latitudes, dense conifers that afford good wind protection.[15] In Canada, they arrive at the roosting site earlier in the evening and leave later in the morning on colder days.[16] At the roosting site, they tend to occupy trees singly; they do not huddle. They sleep with the bill tucked under the scapular (shoulder) and back feathers, adopting this position sooner on colder nights.[17] During the night, they may also regurgitate in the form of pellets the undigested parts of what they ate during the day. Such pellets can be found on the ground and then used to determine at least part of the birds' diet.[18]
Level flight appears slow and labored. As measured in wind tunnels, minimum and maximum sustained flight speeds are 14.5 km/h and 50 km/h (9 mph and 31 mph), respectively.[19] Flight is commonly interrupted by nonflapping phases. Descents from heights consist of repeated J-shaped swoops with the wings nearly closed.
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.[20] Magpies formerly followed American bison herds (from which they gleaned ticks and insects), as well as the bands of Plains Indians that hunted the bison so they could scavenge carcasses. 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. Today, black-billed magpies remain relatively tame in areas where they are not hunted. However, they become very wary in areas where they are often shot at or disturbed. During the first half of the 20th century, black-billed magpies were considered detrimental to game-bird populations (due to them sometimes stealing bird eggs) and domestic stock (pecking at sores on cattle), and were systematically trapped or shot. Bounties of one cent per egg or two cents per head were offered in many states. In Idaho, the death toll eventually amounted to an estimated 150,000. In 1933, 1,033 magpies were shot in Washington's Okanogan valley by two teams of bounty hunters. Many magpies also died from eating poison set out for coyotes and other predators.[21]
If regularly disturbed at the nest, magpie pairs will eventually either move the eggs[22] or abandon the clutch altogether, but in the first instance they will defend the nest aggressively. 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.[4] [23]
Many suburban songbird lovers dislike magpies because of their reputation for stealing eggs, but studies have shown that eggs make up only a small proportion of what magpies feed on during the reproductive season, and that songbird populations do not fare worse in the presence of magpies.[11]
A common misconception about magpies in general is that they like to steal bright or shiny things. This reputation belongs to the Eurasian magpie (Pica pica) rather than the black-billed magpie, and at any rate an experiment conducted at Exeter University has shown that the reputation is undeserved: Eurasian magpies displayed caution around shiny objects rather than being attracted to them.[24]
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.[1]
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".[25] State or local regulations may limit or prohibit killing these birds as well. The species is not threatened, and in some areas, it has benefited from forest fragmentation and agricultural developments. Like many corvids, however, it is susceptible to West Nile virus.
In Canada, however, black-billed magpies do not appear on the list of birds protected by the Migratory Birds Convention Act.[26] Provincial laws also apply, but in Alberta, magpies may be hunted and trapped without a license.[27]
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.[21]
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 black areas on the wings and tail showing iridescent hints of blue or blue-green. It is one of only four North American songbirds whose tail makes up half or more of the total body length (the others being the yellow-billed magpie, the scissor-tailed flycatcher, and the fork-tailed flycatcher).
This species prefers generally open habitats with clumps of trees. It can therefore be found in farmlands and suburban areas, where it comes into regular contact with people. Where persecuted it becomes very wary, but otherwise it is fairly tolerant of human presence. Historically associated with bison herds, it now lands on the backs of cattle to glean ticks and insects from them. Large predators such as wolves are commonly followed by black-billed magpies, who 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 is one of the few North American birds that build a domed nest, which is made up of twigs and sits near the top of trees, usually housing 6–7 eggs. Incubation, by the female only, starts when the clutch is complete, and lasts 16–21 days. The nestling period is 3–4 weeks.
