Lifespan, longevity, and ageing

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Maximum longevity: 22.9 years (wild)
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Untitled

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There are three recognized subspecies: Q. q. versicolor, often called the bronzed grackle; Q. q. quiscula, known as the Florida grackle; and Q. q. stonei, often referred to as the purple grackle. In areas where the bronzed and purple grackles overlap, a small amount of intermediate forms have been designated Q. q. ridgwayi, and show strong barring on the backs.

Albinism has been recorded fairly often in this species, but it is usually partial.

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Behavior

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Common grackles use physical displays and vocalizations to communicate. Common grackles produce one song type, which is individually distinctive and is probably used as identification. The harsh song is said to sound much like a squeaking, rusty gate. The male song is most often heard around the date of the first copulation, and its frequency decreases over the course of incubation. Females sing much less frequently than males, and appear to sing most often when song-answering with their mate.

Communication Channels: visual ; acoustic

Perception Channels: visual ; tactile ; acoustic ; chemical

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Conservation Status

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Common grackles are one of the most successful and wide-spread species in North America, with an estimated total population of 97,000,000 individuals. Eastern forests were cleared for agriculture in 1700s and 1800s, creating additional nesting habitat and increased food sources. The planting of shelterbelts has facilitated the spread of this species in the west. Common grackles are very common, and are killed as an agricultural pest in many parts of their range.

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

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Benefits

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Common grackles are one of the most significant agricultural pests today, causing millions of dollars in damage to sprouting corn. The roosting sites of common grackles and other blackbirds may harbor the fungus, which causes histoplasmosis, a human respiratory disease that can be fatal. However, only roost sites that have been used for more than 3 years tend to become infected. Nonetheless, this phenomenon is used as one of the primary justifications for killing large numbers of roosting blackbirds and starlings.

Negative Impacts: injures humans (carries human disease); crop pest

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Benefits

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Common grackles may help to control populations of crop pests.

Positive Impacts: controls pest population

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Associations

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Common grackles provide food for several birds and small animals as well as helping to control populations of insects and other prey. They also disperse seeds through their droppings during the parts of the year when seeds make up most of their diet.

Common grackle nests are occasionally parasitized by brown-headed cowbirds, although cowbird eggs in these nests are largely unsuccessful.

Ecosystem Impact: disperses seeds

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Trophic Strategy

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During breeding, common grackles' diets consist mainly of insects and other invertebrates. The diet may also include goldfish, minnows, crayfish, small frogs, salamanders, mice, and small bats, which are caught from the air. During migration and winter, common grackles eat mostly grains from farm fields and seeds, particularly corn and acorns. They also eat some fruits.

Common grackles are generally very opportunistic foragers, they follow plows in search of grubs, and even consume human garbage. Adults have been observed snatching earthworms from feeding robins. Grackles forage primarily on the ground, though they also utilize trees, shrubs, and other vegetation. These gregarious birds feed in large flocks, especially outside of the breeding season. They primarily use their bills instead of their feet to uncover food on the ground.

Animal Foods: birds; mammals; amphibians; fish; insects; terrestrial non-insect arthropods; terrestrial worms; aquatic crustaceans

Plant Foods: seeds, grains, and nuts; fruit

Primary Diet: carnivore (Insectivore , Eats non-insect arthropods)

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Distribution

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Common grackles range over almost all of eastern North America east of the Rockies, extending far into Canada in the summer breeding season.

Biogeographic Regions: nearctic (Native )

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Habitat

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Common grackles are found in open areas with scattered trees (preferably coniferous), including around human habitation. They can also be found in farmlands, orchards and swamps. Common grackles have adapted so well to human structures that they are quite common in open areas such as suburban developments, city parks and cemeteries. In fact, human alteration of forested habitats for agriculture has resulted in an expansion of the range of common grackles and an increase in their numbers.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest

Other Habitat Features: urban ; suburban ; agricultural

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Life Expectancy

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The maximum lifespan recorded is just over 22 years, although most do not live that long. About half of all common grackles reach adulthood.

Range lifespan
Status: wild:
22 (high) years.

Average lifespan
Status: wild:
275 months.

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Morphology

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Common grackles are medium-sized blackbirds. Their plumage is black, and has a sheen that is glossy and iridescent. Generally, their heads, necks and breasts are glossy purplish-blue or bluish-green. However, common grackles in different parts of North America have somewhat different colored plumage. In New England and in the West, the subspecies has a brassy bronze body coloration. East of the Allegheny Mountains, the body is purple, and in the southeast the feathers have a greenish hue. Common grackles have long, sharp, black bills and yellow eyes. Their tails are long and keel-shaped.

Adult common grackles are 28 to 34 cm long. Females are smaller and duller than males and have a shorter tail. Males usually weigh about 122 g while females weigh around 94 g. Young common grackles look similar to adults, but have brown plumage and brown eyes.

Range mass: 92 to 131 g.

Range length: 28 to 34 mm.

Other Physical Features: endothermic ; bilateral symmetry ; polymorphic

Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Associations

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Humans kill large numbers of common grackles to control populations in areas where they destroy crops. Fox squirrels, eastern chipmunks, rat snakes, domestic cats, gray squirrels, bullsnakes, and racoons eat the eggs and nestlings of common grackles. Red-tailed hawks, northern harriers, Cooper's hawks, short-eared owls, and great horned owls are predators of adult common grackles.

Known Predators:

  • humans (Homo sapiens)
  • fox squirrels (Sciurus niger)
  • eastern chipmunks (Tamias striatus)
  • rat snakes (Pantherophis obsoletus)
  • domestic cats (Felis silvestris)
  • gray squirrels (Sciurus carolinensis)
  • bullsnakes (Pituophis catenifer sayi)
  • raccoons (Procyon lotor)
  • red-tailed hawks (Buteo jamaicensis)
  • northern harriers (Circus cyaneus)
  • Cooper's hawks (Accipiter cooperii)
  • short-eared owls (Asio flammeus)
  • great horned owls (Bubo virginianus)
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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Reproduction

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Common grackles are usually monogamous, though polygyny occasionally occurs. Pair formation begins in flocks in early spring. Formation of pairs is indicated by flights and mutual displays between a single female and multiple males. A male and a female show preference for one another by flying together, usually with the female in the lead. As the pair-bond is established, the pair leaves the flock to fly and sing together.

The female of a pair typically chooses the nest site. Though this is usually done after pair formation, females sometimes chosen sites several weeks before pairing with a male. From pair formation through incubation, the male remains in close association with his mate by perching near her, following her, and engaging in mutual displays. This pattern exhibited by the male probably functions to guard against extra-pair copulations. Once incubation has begun, his attentiveness decreases steadily.

Adult common grackles sometimes function as helpers to other birds of the species. In one recorded case, two males frequently showed up at the same nest to feed the young, and there was no antagonistic behavior between them. It is assumed that one of the males was the father of the offspring.

Mating System: monogamous ; cooperative breeder

Common grackle nests are built by the female, usually in coniferous trees, though more unusual sites have been documented. These include woodpecker holes, on rafters, under the eaves of barns, in the crannies of ospreys' large nests, and in clumps of cattails. The nests are large and bulky, constructed of woody stems, leaves and fine grasses. Other materials may be used, including fishing line, feathers, manure and tape. The nest cup is lined with mud, and finally fine grasses and horsehair.

Copulation begins soon after the female has completed the nest. She lays 1 to 7 eggs (usually 5 to 6). The eggs are smooth-textured, and highly variable in color. They are typically light blue to pearl gray, though they range from nearly white to dark brown. Some are scrawled with blackish brown, especially at the larger end, and others are spotless. The female incubates the eggs for 12 to 14 days. At this time, about half of common grackle males desert the female and the nest. Those that remain participate in parental care after hatching.

During incubation, various displays and calls are given by both sexes. Parental care, including brooding and feeding, is performed mainly by the female, although males have been observed feeding young. The food supply is monopolized by more aggressive nestlings. The young leave the nest about 12 to 15 days after hatching, and remain near the nest for another 1 to 2 days. The adults continue to feed the young for several weeks.

Common grackle nests are sometimes parasitized by brown-headed cowbirds, but the cowbird eggs in these nests are largely unsuccessful. Common grackles are usually single-brooded, but can double-brood in some areas. Common grackles breed between March and July.

Breeding interval: Common grackles breed once yearly. Common grackles are usually single-brooded, but can double-brood in some areas.

Breeding season: Common grackles breed between March and July.

Range eggs per season: 1 to 7.

Average eggs per season: 5.

Range time to hatching: 12 to 14 days.

Range fledging age: 12 to 15 days.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

Average birth mass: 105 g.

Average eggs per season: 5.

Brooding and feeding of the altricial chicks are performed mainly by females, although there have been reports of males assisting in feeding the young. The food supply is monopolized by more aggressive nestlings. The young leave the nest about 12 to 17 days after hatching, though they remain near the nest for another 1 to 2 days. Adults continue to feed the young for several weeks. About half of all grackle males remain with the female through hatching and help in the parental care of the young.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Female); pre-independence (Provisioning: Male, Female)

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Ivory, A. 1999. "Quiscalus quiscula" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Quiscalus_quiscula.html
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Brief Summary

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The Common Grackle (Quiscalus quiscula) is an abundant and gregarious blackbird found in partly open situations with scattered trees, open coniferous and deciduous woodlands, forest edges, and suburbs. It breeds across approximately the eastern two thirds of Canada (from Alberta to southern Quebec) and the United States (from Montana, Colorado and easten New Mexico to the Atlantic and Gulf Coasts), with the winter range contracting to the southeast of the much broader breeding range. The range has been expanding westward in recent decades. Two forms (both appearing all black at a distance) were at one time recognized as distinct species: The "Bronzed Grackle", which occurs in most of New England and west of the Appalachians, has a bronze back, blue head, and purple tail; the smaller "Purple Grackle", found east of the Appalachians, has a narrow bill, purple head, bottle green back, and purple tail. Birds from the mid-Atlantic states show variable head color and a purplish back with iridescent bands of variable color. The familiar song of the Common Grackle resembles the sound of a creaking gate; the call note is a loud, deep chuck. Common Grackles are omnivorous . They forage mainly by walking on the ground or wading in very shallow water. Outside the breeding season, they usually forage in flocks. Common Grackles often nest in small colonies of 10 to 30 pairs (sometimes as many as 100 or more) and several males may perch in adjacent treetops to sing their creaking, grating songs. In courtship, the male fluffs out his body feathers, partly spreads his wings and tail, and delivers a short scraping song; he also postures with his bill pointing straight up. The nest is typically built in dense vegetation less than 6 m above the ground. The nest, which is built by the female, is a bulky open cup of weeds, grass, and twigs, usually with some mud added, and the inside is lined with fine grass. The 4 to 5 (sometimes as few as two or as many as 6) pale blue eggs are blotched with brown. Incubation is by the female only for 12 to 14 days. Both parents feed the young, bringing them mostly insects. The young leave the nest around 16 to 20 days after hatching. Common Grackles are present year-round across much of their range. Migration usually involves large flocks. In the north, migration takes place quite early in spring and rather late in the fall. (Kaufman 1996; AOU 1998; Dunn and Alderfer 2011)
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Comprehensive Description

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Quiscalus quiscula (Linnaeus)

The grackle has been reported very rarely as a cowbird victim. To the six earlier records (Friedmann, 1963:135) may be added 5 more: a parasitized nest in Greeley County, Nebraska (Bennett, 1974), 1 in Ontario (Ontario nest records files, Toronto), 1 at Seneca, Maryland, 22 April 1941 (in the Delaware Museum of Natural History); and 2 other records from New York State (Bull, 1974: 537). The record from Maryland is the first one involving the host subspecies Q. quiscula stonei (all the others refer to Q. quiscula versicolor). The

Nebraska record is the second for the cowbird race M. ater artemisiae.

It should be pointed out that numerous experiments have shown the grackle to be an accepter species (Rothstein, 1975a). Therefore, the small number of records of parasitism cannot be due to rejection behavior by the host, but must reflect an actual absence of parasitism by the cowbird. The reason for the lack of parasitism is not clearly known. The cowbird may avoid parasitizing species as large as the grackle, but the American robin and brown thrasher are nearly as large and have been found to be parasitized many more times than the grackle, even though they are rejecter species. Perhaps the grackle's colonial nesting may be a factor. It may be difficult for cowbirds to escape detection when entering grackle colonies. But many grackles do not nest in colonies, in which case other factors may be responsible for the low incidence of parasitism. In the nest card records files at Cornell University there are data on 1795 nests of the grackle, none of which contained cowbird eggs. (There were indefinite statements of 2 of them being parasitized, but nothing in the way of a reliable record). In the Ontario files at Toronto are data on 1399 nests, only 1 of which was parasitized.

WESTERN TANAGER
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Friedmann, Herbert, Kiff, Lloyd F., and Rothstein, Stephen I. 1977. "A further contribution of knowledge of the host relations of the parasitic cowbirds." Smithsonian Contributions to Zoology. 1-75. https://doi.org/10.5479/si.00810282.235

Common grackle

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Common grackle
 src=
A grackle’s iridescent head and yellow eye.

The common grackle (Quiscalus quiscula) is a large icterid found in large numbers through much of North America. First described in 1758 by Carl Linnaeus, the common grackle has three subspecies. Adult common grackles have a long and dark bill, pale yellow eyes, and a long tail. Adults often have an iridescent appearance on their head, especially males. Common grackles are found in much of North America east of the Rocky Mountains.

Taxonomy

The common grackle was first described in 1758 by Carl Linnaeus in the tenth edition of Systema Naturae, as Gracula quiscula. It was assigned to the genus Quiscalus by French ornithologist Louis Jean Pierre Vieillot in his 1816 Dictionnaire d'histoire naturelle.[2]

Three subspecies are recognized:[3][4]

  • the Florida grackle (Q. q. quiscula) (Linnaeus 1758), the nominate subspecies
  • the purple grackle (Q. q. stonei) (Chapman, 1935)[5]
  • the bronzed grackle (Q. q. versicolor) (Vieillot, 1816)

Description

 src=
Iridescent male common grackle

Adult common grackles measure from 28 to 34 cm (11 to 13 in) in length, span 36–46 cm (14–18 in) across the wings, and weigh 74–142 g (2.6–5.0 oz).[6] Common grackles are less sexually dimorphic than larger grackle species, but the differences between the sexes can still be noticeable. The male, which averages 122 g (4.3 oz), is larger than the female, at an average of 94 g (3.3 oz).[7] Adults have a long, dark bill, pale yellowish eyes, and a long tail; their feathers appear black with purple, green, or blue iridescence on the head, and primarily bronze sheen in the body plumage. Adult females, beyond being smaller, are usually less iridescent; their tails in particular are shorter, and unlike the males, do not keel (display a longitudinal ridge) in flight and are brown with no purple or blue gloss. Juveniles are brown with dark brown eyes.

When grackles are in a group, they are referred to as a "plague."[8]

Distribution and habitat

CommonGrackle
Common grackle, mating display (Central Park NYC)
 src=
Common grackle (Quiscalus quiscula) in Central Park, New York

The breeding habitat is open and semiopen areas across North America east of the Rocky Mountains. The nest is a well-concealed cup in dense trees (particularly pine) or shrubs, usually near water; sometimes, the common grackle nests in cavities or in man-made structures. It often nests in colonies, some being quite large. Bird houses are also a suitable nesting site. Four to seven eggs are in a clutch.

This bird is a permanent resident in much of its range. Northern birds migrate in flocks to the Southeastern United States. The distribution of the common grackle is largely explained by annual mean temperature, and the species has expanded its range by greater than three-fold since the last glacial maximum, approximately 22,000 years ago.[9]

Ecology and behavior

Foraging and diet

 src=
Bird (grackle) close up, standing by 1 intact and 2 pulled corn sprouts. Common grackles damage corn by pulling up newly sprouted plants.

The common grackle forages on the ground, in shallow water, or in shrubs; it may steal food from other birds. It is omnivorous, eating insects, minnows, frogs, eggs, berries, seeds, grain, and even small birds and mice. Grackles at outdoor eating areas often wait eagerly until an unwary bird drops some food. They rush forward and try to grab it, often snatching food out of the beak of another bird. Grackles prefer to eat from the ground at bird feeders, making scattered seed an excellent choice of food for them. Grackles can be regularly seen foraging for insects, especially after a lawn trimming.

Grackles have a unique adaptation in the keel within their bill which allows them to crack and cut hard nuts or kernels. The keel projects downward from the horny palate and is sharper and more abrupt anterior. It extends below the level of the tomium and is used in a sawing motion to score open acorns or dried kernels. Large adductor muscle within their jaw compared to other icterids also makes this adaptation even more useful for opening hard seeds and acorns.[10]

Along with some other species of grackles, the common grackle is known to practice "anting", rubbing insects on its feathers possibly to apply liquids such as formic acid secreted by the insects.

Vocals

The grackle's song is particularly harsh, especially when these birds, in a flock, are calling. Songs vary from year-round chewink chewink to a more complex breeding season ooo whew, whew, whew, whew, whew call that gets faster and faster and ends with a loud crewhewwhew! It also occasionally sounds like a power line buzzing. The grackle can also mimic the sounds of other birds or even humans, though not as precisely as the mockingbird, which is known to share its habitat in the Southeastern United States.

Breeding

In the breeding season, males tip their heads back and fluff up feathers to display and keep other males away. This same behavior is used as a defensive posture to attempt to intimidate predators. Male common grackles are less aggressive toward one another, and more cooperative and social, than the larger boat-tailed grackle species.

Relationship with humans

The range of this bird expanded west as forests were cleared. In some areas, it is now considered a pest by farmers because of its large numbers and fondness for grain. Despite a currently robust population, a recent study by the National Audubon Society of data from the Christmas Bird Count indicated that populations had declined by 61% to a population of 73 million from historic highs of over 190 million birds.[11]

Unlike many birds, the common grackle benefits from the expansion of human populations due to its resourceful and opportunistic nature. Common grackles are considered to be a serious threat to crops by some, and are notoriously difficult to control; this usually requires the use of hawks or similar large birds of prey.[12]

Proposed magnetoreceptivity

Though the exact mechanism is poorly understood, several studies have examined the ability of the common grackle to interpret the Earth's magnetic field—or in this case, the variability of it. The common grackle (like most of its Quiscalus relatives) has been found to be attuned to a dynamic magnetic field to a scientifically significant degree.[13]

Gallery

References

  1. ^ BirdLife International (2018). "Quiscalus quiscula". IUCN Red List of Threatened Species. 2018. Retrieved 15 December 2018.old-form url
  2. ^ Oberholser, Harry (October 1919). "Races of Quiscalus quiscula". The Auk. 36 (4): 549–555. doi:10.2307/4073352. JSTOR 4073352.
  3. ^ "Quiscalus quiscula". Integrated Taxonomic Information System. Retrieved 28 May 2017.
  4. ^ Gill, Frank; Donsker, David, eds. (2017). "New World warblers & oropendolas, Bananaquit". World Bird List Version 7.2. International Ornithologists' Union. Retrieved 28 May 2017.
  5. ^ Chapman, Frank (January 1935). "Further Remarks on the Relationships of the Grackles of the Subgenus Quiscalus". The Auk. 52 (1): 21–29. doi:10.2307/4077103. JSTOR 4077103.
  6. ^ "Common Grackle". Cornell Lab of Ornithology.
  7. ^ "Quiscalus quiscula, common grackle". Animal Diversity Web.
  8. ^ Murphy-Hiscock, Arin (January 2012). Birds - A Spiritual Field Guide: Explore the Symbology and Significance of These Divine Winged Messengers. Adams Media. p. 86. ISBN 978-1-4405-2688-6.
  9. ^ Capainolo, Peter; Perktaş, Utku; Fellowes, Mark D.E. (2020-07-01). "Late Quaternary Range Dynamics in the Common Grackle Quiscalus quiscula". Ardea. 108 (1): 95. doi:10.5253/arde.v108i1.a8. ISSN 0373-2266.
  10. ^ Beecher, William (1951). "Adaptations for Food-Getting in the American Blackbirds" (PDF). The Auk. 68 (4): 420–422. doi:10.2307/4080840. JSTOR 4080840.
  11. ^ Strassburg, Matthew David (November 2011). The evaluation of Christmas Bird Counts as an indicator of population trends and habitat selection in blackbirds and starlings (PDF) (MSc). North Dakota State University. Retrieved January 19, 2019.
  12. ^ "Murder Most Fowl". Time Magazine. Archived from the original on January 27, 2007.
  13. ^ Schnell, Gary D.; Dubois, Robert L.; Hutchison, Victor H. (1992). "Natural and Induced Remanent Magnetism in Birds" (PDF). The Auk. 109 (1): 43–56. doi:10.2307/4088265. JSTOR 4088265 – via Department of Geology and Geophysics, University of Oklahoma.

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Common grackle: Brief Summary

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Common grackle  src= A grackle’s iridescent head and yellow eye.

The common grackle (Quiscalus quiscula) is a large icterid found in large numbers through much of North America. First described in 1758 by Carl Linnaeus, the common grackle has three subspecies. Adult common grackles have a long and dark bill, pale yellow eyes, and a long tail. Adults often have an iridescent appearance on their head, especially males. Common grackles are found in much of North America east of the Rocky Mountains.

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