The Boat-tailed Grackle (Quiscalus major), a large blackbird of the southeastern United States, was not distinguished from the Great-tailed Grackle (Quiscalus mexicanus) until the 1970s, but the two forms overlap on the coasts of Texas and Louisiana without interbreeding. The Boat-tailed Grackle is generally more closely associated with water, such as around marshes and beaches, although in Florida it may be found inland. These birds eat a range of foods, mainly taken from water, such as aquatic insects, snails, crayfish, crabs, tadpoles, frogs, and small fish, but also including terrestrial insects and the eggs and young of other birds. During some seasons, seeds and grains are an important component of the diet. Nesting is in colonies, generally near water. These birds are often very common within their range, which in recent decades has extended northward along the Atlantic coast to Long Island (New York, U.S.A.). The distribution extends southward through peninsular Florida and west along the Gulf Coast to southeastern Texas. There is generally little movement between seasons, although a few northern breeders may move south in the fall. The Boat-tailed Grackle is one of only about a dozen bird species that are endemic to the United States (i.e., found nowhere else in the world). (Kaufman 1996; AOU 1998)
- American Ornithologists' Union. 1998. Check-list of North American Birds, 7th edition. American Ornithologists' Union, Washington, D.C.
- Kaufman, K. 1996. Lives of North American Birds. Houghton Mifflin, Boston.
The Boat-tailed Grackle (Quiscalus major) was not distinguished from the Great-tailed Grackle (Quiscalus mexicanus) until the 1970s, but the two forms overlap on the coasts of Texas and Louisiana without interbreeding. The Boat-tailed Grackle is generally more closely associated with water, such as marshes and beaches, although in Florida it may be found inland. These birds eat a range of foods, mainly taken from water, such as aquatic insects, snails, crayfish, crabs, tadpoles, frogs, and small fish, but also including terrestrial insects and the eggs and young of other birds. During some seasons, seeds and grains are an important component of the diet. Nesting is in colonies, generally near water. These birds are often very common within their range, which has extended northward along the Atlantic coast to Long Island (New York, U.S.A.) in recent decades. The distribution extends southward through peninsular Florida and west along the Gulf Coast to southeastern Texas. There is generally little movement between seasons, although a few northern breeders may move south in the fall. (Kaufman 1996; AOU 1998)
- American Ornithologists' Union. 1998. Check-list of North American Birds, 7th edition. American Ornithologits' Union, Washington, D.C.
- Kaufman, K. 1996. Lives of North American Birds, Houghton Mifflin, Boston.
Global Range: RESIDENT: along Atlantic coast from Long Island and New Jersey south, throughout peninsular Florida, and west along Gulf coast to southeastern Texas (AOU 1983).
endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Length: 42 cm
Weight: 214 grams
Comments: Coastal salt marshes and barrier and sea islands, around ponds and streams (Florida peninsula), farmland, towns and cities. BREEDING: Nests generally near or over water, in willows, cattails, sawgrass, bulrushes; also up to 25 m in trees. See Dunham (1990) for information on nest-site selection in Florida.
Habitat and Ecology
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Comments: Eats various invertebrates, grain, some small vertebrates; forages on ground, mudflats, shallow water (Terres 1980).
Known prey organisms
This list may not be complete but is based on published studies.
Life History and Behavior
Lifespan, longevity, and ageing
Clutch size 1-5 (usually 2-3 in FL, Bancroft 1986). Two, some- times 3 broods/yr. Incubation 13-14 days, by female. Young tended by female, leave nest at 20-23 days. Nesting success varies greatly among localities & yrs. Usually colonial.
Molecular Biology and Genetics
Barcode data: Quiscalus major
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Quiscalus major
Public Records: 7
Specimens with Barcodes: 8
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
IUCN Red List Assessment
Red List Category
Red List Criteria
The boat-tailed grackle (Quiscalus major) is a passerine bird of the family Icteridae found as a permanent resident on the coasts of the southeastern United States. It is found in coastal saltwater marshes, and, in Florida, also on inland waters. The nest is a well-concealed cup in trees or shrubs near water; three to five eggs are laid.
The male boat-tailed grackle is 37–43 cm (15–17 in) long and weighs 165–250 g (5.8–8.8 oz). Adult males have entirely iridescent black plumage, a long dark bill, a pale yellowish or brown iris and a long keel-shaped tail. The adult female is much smaller at 26–33 cm (10–13 in) long and a weight of 90–115 g (3.2–4.1 oz). She is also distinctive via her shorter tail and tawny-brown coloration, which covers the body apart from the darker wings and tail. The wingspan in adult birds is 39–50 cm (15–20 in). In standard measurements, this species measures 13–20 cm (5.1–7.9 in) along the wing bone, 11–20 cm (4.3–7.9 in) in tail length, 2–4.2 cm (0.79–1.65 in) along the culmen and 3.6–5.8 cm (1.4–2.3 in) along the tarsus. On average, the boat-tailed grackle weighs about 10% more than the closely related great-tailed grackle although the male of that species has an even longer tail.
Young males are black but lack the adult's iridescence. Immature females are duller versions of the adult female and have blotches or spots on the breast. The eye color of the boat-tailed grackle varies with range. Gulf Coast and inland birds have dark eyes, where as Atlantic birds have pale eyes.
The boat-tailed grackle was first described by French naturalist Louis Jean Pierre Vieillot in 1819. Its specific epithet major means "larger" in Latin. Despite its restricted range, there are four subspecies of the boat-tailed grackle, differing in size and iris color. The boat-tailed grackle was once considered the same species as the great-tailed grackle. The great-tailed species is generally quite similar of slightly smaller body size, but has a longer tail and lacks this species' distinct domed head shape. The common grackle, with which the boat-tailed species often overlaps along the Atlantic coastline, is noticeably smaller and shorter-tailed, as well as lacking the domed head shape.
These birds forage on the ground, in shallow water, or in shrubs; they will steal food from other birds. They are omnivorous, eating insects, minnows, frogs, eggs, berries, seeds, and grain, even small birds.
Boat-tailed grackles have established significant populations in several United States Gulf Coast cities and towns where they can be found foraging in trash bins, dumpsters, and parking lots.
This bird's song is a harsh jeeb, and it has a variety of typically grackle-like chatters and squeaks.
- BirdLife International (2012). "Quiscalus major". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- "FieldGuides: Species Detail". eNature. Retrieved 2013-03-05.
- Bancroft, GT (1984). "Growth and sexual dimorphism of the Boat-tailed Grackle". Condor 86 (4): 423–432. doi:10.2307/1366822. JSTOR 1366822.
- "Boat-tailed Grackle, Life History, All About Birds – Cornell Lab of Ornithology". Allaboutbirds.org. Retrieved 2013-03-05.
- New World Blackbirds: The Icterids by Alvaro Jaramillo & Peter Burke. Christopher Helm Publishing (1999), ISBN 978-0713643336
- CRC Handbook of Avian Body Masses, John B. Dunning Jr. (ed.). CRC Press (1992), ISBN 978-0849342585.
- eBird.org: Grackles – Are you getting them right?
Names and Taxonomy
Comments: Formerly regarded as conspecific with Q. MEXICANUS, but sympatry without interbreeding known from Louisiana to Texas (AOU 1998). A sister taxon of Q. MEXICANUS and probably constitutes a superspecies with it (AOU 1998). See Avise and Zink (1988) for information on genetic divergence between Q. MEXICANUS and Q. MAJOR. Most closely related to Q. NIGER, according to a phylogeny based on morphological characteristics (Bjorklund 1991). However, mtDNA data indicate that Q. MAJOR and Q. MEXICANUS are sister taxa (Zink et al. 1991). Often placed in genus CASSIDIX (AOU 1998).