By Patrick Koby
Geographic Range
The great-tailed grackle, Quiscalus mexicanus, was historically almost exclusively found in South and Central America, but human alteration of the environment has caused the birds to expand their range to include parts of the United States and Canada (Christensen, 2000). Their current range in the United States is north to eastern Oregon, with individuals sighted as far north as Canada (Sauer et al., 1997), south to northwest Peru, and as far east as Western Arkansas (Jaramillo, 1999).
Biogeographic Regions:
nearctic 
(native ); neotropical (native ).
Habitat
The great-tailed grackle is found in a variety of habitats, including groves, thickets, farms, towns, city parks, (Peterson, 1990), mangroves, and marshes (Jaramillo, 1999).
Aquatic Biomes:
coastal .
Wetlands: marsh .
Other:
urban ; suburban ; agricultural ; riparian .
Physical Description
The male great-tailed grackle is a large blackbird that appears purple-glossed. He averages approximately 45 cm in length and has a long ample tail. A potential identification problem exists between the boat-tailed grackle and the great-tailed, but the tail of the great-tailed tends to be wider and longer. The female is brown with a pale breast, and averages 35 cm in length. Both sexes have distinctive yellow eyes as adults (Peterson, 1990).
Some key physical features:
endothermic ; bilateral symmetry .
Reproduction
Spring
Early in the spring males establish small territories and begin the process of attracting females. The breeding is polygynous, and the females nest in the territory of one male. Several females will nest in a single male's territory, and mate with him. First year males are excluded from breeding but young females are not. The main display is the "ruff-out" which is accompanied by a song. In the "ruff-out" the tail is fanned while the body feathers are ruffed and the head is arched upwards as it sings. The wings are drooped and quivered or held out towards the sides. The male courtship display differs in that it is more exaggerated, the bill is pointed down rather than up, and the wings are rapidly quivered while the bird produces distinctive "cheat" notes. The female may respond by drooping and quivering the wings as the tail is cocked and gives "che" calls. (Jaramilo 1999)
Mating systems:
polygynous .
First year males are excluded from mating, but young females (1 yr.) are not (Jaramillo, 1999). The breeding season begins in early April. Nesting occurs in colonies of few to thousands, with the nests placed close together. The males tend to avoid confrontation with low key disputes. The females will fight over the choice of nest sites, and will steal nest building materials from one another. Clutch sizes tend to average 3 to 4 eggs, and females incubate them for 13 to 15 days. The young are born altricial and leave the nest at 20 to 23 days (Harrison, 1978).
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous .
Chicks are born immobile, downless, with their eyes closed, and need to be fed by a parent. The males do not participate in nesting or care of the young.
Parental investment:
altricial ; female parental care .
Lifespan/Longevity
A banded great-tailed grackle lived at least 12.5 years. (USGS, 2002)
Behavior
Great-tailed grackles prefer to roost and forage in large groups, particularly in the non-breeding months. In the winter foraging tends to occur in single sex groups. (Jaramilo, 1999)
Key behaviors:
flies; motile ; sedentary ; territorial ; social .
Food Habits
The great-tailed grackle is known to eat insects, lizards, aquatic invertebrates and vertebrates, fruit, grain, and grass seed (Sibley, 2001). They are also known to remove and eat ectoparasites from livestock. Male nestlings appear to require more food than females of the same age (Ehrlich et al., 1988).
Primary Diet:
omnivore .
Animal Foods:
reptiles; fish; eggs; insects; terrestrial non-insect arthropods.
Plant Foods:
seeds, grains, and nuts; fruit.
Economic Importance for Humans: Negative
Adult males are nearly granivorous (Jaramillo, 1999)
Ways that these animals might be a problem for humans:
crop pest.
Economic Importance for Humans: Positive
May aid in agricultural pest control.
Conservation Status
IUCN Red List: [link]:
Least Concern.
US Migratory Bird Act: [link]:
No special status.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
Over the past 30 years the great-tailed grackle has expanded its range in the U.S. at a rate of greater than 2.5% annually. This expansion is due to human modification of the landscape. Irrigation in arid areas, urbanization, and increasing cropland have all contributed to this expansion of range.(Christensen 2000)
Contributors
Patrick Koby (author), University of Arizona.
Todd McWhorter (editor), University of Arizona.
