Great-tailed Grackle Quiscalus mexicanus Scientific name definitions

The Great-tailed Grackle is a large, sexually dimorphic, widely distributed blackbird. The male is glossy black with purple iridescence, a long keel-shaped tail, a massive bill, and yellow eyes. Flamboyant in its behavior as well as its plumage, the male has a large and varied vocal repertoire, and elaborate courtship and territorial displays. The female, about half the size of the male, is dark brown and has a smaller keel-shaped tail, and yellow eyes.

The Great-tailed Grackle is closely related to the Boat-tailed Grackle (Quiscalus major). The two species were considered conspecific during much of the 1900s, but have been shown to be reproductively isolated and were split in 1973. The Boat-tailed Grackle, which occurs in Florida and coastal areas of the Gulf states and the eastern United States, breeds in open marsh in coastal areas. In contrast, the Great-tailed Grackle, which occurs in the midwestern and western United States south to northern South America, breeds mainly in drier coastal habitats, typically in areas with scattered trees near standing water. It nests high in large trees, as well as in marsh vegetation. Inland, the Great-tailed Grackle more frequently nests in grasslands, agricultural areas, and towns, whereas the Boat-tailed Grackle is more likely to nest in marshy areas. The Great-tailed Grackle forages in open grassy areas, such as grasslands, pastures, and lawns, but also forages in trees or even around dumpsters in cities. Its diet is varied and includes arthropods, small vertebrates, plant matter, and human refuse.

The social mating system of the Great-tailed Grackle is polygynous, and individuals of both sexes are frequently non-faithful to their social mates. The male defends a small territory, comprising one to several trees, in which females nest. Only adult males acquire territories, and most territorial males are at least 3 years old. In contrast, females usually breed in their second year. Social bonds are ephemeral, and females may switch nesting trees and social mates within or between breeding seasons. The male defends nestlings and fledglings hatched in his territory from potential predators. Most parental care is provided by the female, but a few recent records indicate the adult male will feeding fledglings or nestlings. Fewer male than female nestlings survive, and adult male survival may be lower than adult female survival, resulting in a female-biased adult sex ratio.

During the 1900s, the Great-tailed Grackle experienced a rapid, large-scale expansion of its North American range. In 1900, the northern limits of its range barely extended into Texas, yet by 2020, the species had nested in at least 17 states and was reported in 21 states and 3 Canadian provinces. This explosive growth occurred mainly after 1960 and coincided with human-induced habitat changes, such as expansion of urbanization and irrigated cropland. This geographic expansion is reflected in the long-term (1967–2019) increasing population trend seen for the United States, a 0.9% per year increase. However, more recently (1987–2019), the United States trend was negative (–1.7% per year), primarily owing to a decline in Texas, though populations generally increased in California, Arizona, and New Mexico. The Great-tailed Grackle has also expanded its range in the Neotropics, though less dramatically so.

The range expansion of the Great-tailed Grackle presents an instructive contrast to species that have been adversely affected by human activities. Its success and its role as a human commensal have made it an agricultural pest and an annoyance to many people, but they have also made it a convenient subject for study. Its behavior is well studied, particularly in Texas (1 Selander, R. K., and D. R. Giller (1961). Analysis of sympatry of Great-tailed and Boat-tailed Grackles. Condor 63: 29–86. Close , 2 Bailey, Z. E., and D. N. Griffin (1969). A study of selected phases of the life-history of the Boat-tailed Grackle in the Commerce (Hunt County, Texas) area. Inland Bird Banding 41: 3–11. Close , 3 Kok, O. B. (1970). Behavior of the Great-tailed Grackle (Quiscalus mexicanus). Ph.D. thesis, University of Texas, Austin, TX, USA. Close , 4 Kok, O. B. (1971). Vocal behaviour of the Great-tailed Grackle (Quiscalus mexicanus prosopidicola). Condor 73: 348–363. Close , 5 Johnson, K., E. DuVal, M. Kielt, and C. Hughes (2000). Male mating tactics and the mating system of great-tailed grackles. Behavioral Ecology 11(2): 132–141. Close , 6 Peer, B. D., and S. G. Sealy (2000a). Conspecific brood parasitism and egg rejection in Great-tailed Grackles. Journal of Avian Biology 31: 271–277. Close , 7 Logan, C. J. (2016a), Behavioral flexibility and problem solving in an invasive bird. PeerJ 4: e1975 Close , 8 Logan C. J. (2016b). How far will a behaviourally flexible invasive bird go to innovate? Royal Society Open Science 3: 160247. Close , 9 Logan, C. J. (2016c). Behavioral flexibility in an invasive bird is independent of other behaviors. PeerJ 4: e2215 Close , 10 Folsom M. A., D. Lukas, M. MacPherson, K. B. McCune, L. Bergeron, A. Bond, A. Blackwell, C. Rowney, and C. J. Logan (2020). Repeated parental care by adult male great-tailed grackles and its association with hormones, fitness, specific populations, and mating strategies. In principle acceptance by Peer Community in Ecology of the version on 15 June 2020. PCI Ecology. Close , 11 Blaisdell A., B. Seitz, C. Rowney, M. Folsom, M. MacPherson, D. Deffner, and C. J. Logan (2021). Do the more flexible individuals rely more on causal cognition? Observation versus intervention in casual inference in great-tailed grackles. Version 5, peer-reviewed and recommended by Peer Community in Ecology. PsyArXiv. Close ), and it has been the subject of several phylogenetic studies (12 Avise, J. C., and R. M. Zink (1988). Molecular genetic divergence between avian sibling species; King and Clapper Rails, Long-billed and Short-billed Dowitchers, Boat-tailed and Great-tailed Grackles and Tufted and Black-crested Titmice. Auk 105(3): 516–528. Close , 13 Freeman, S., and R. M. Zink (1995). A phylogenetic study of the blackbirds based on variation in mitochondrial DNA restriction sites. Systematic Biology 44(3): 409–420. Close , 14 Johnson, K. P., and S. M. Lanyon (1999). Molecular systematics of the grackles and allies, and the effect of additional sequence (cyt b and ND2). Auk 116:759–768. Close , 15 Lanyon, S. M., and K. E. Omland (1999). A molecular phylogeny of the blackbirds (Icteridae): five lineages revealed by cytochrome-b sequence data. Auk 116(3):629–639. Close , 16 Powell, A. F. L. A., F. K. Baker, and S. M. Lanyon (2008). A complete species-level phylogeny of the grackles (Quiscalus), including the extinct Slender-billed Grackle, inferred from mitochondrial DNA. The Condor 110(4):718–728. Close ). Literature also exists on its range expansion (reviews in 17 Dinsmore, J. J., and S. J. Dinsmore (1993). Range expansion of the Great-tailed Grackle in the 1900s. Journal of the Iowa Academy of Science 100(2): 54–59. Close and 18 Wehtje, W. (2003). The range expansion of the Great-tailed Grackle (Quiscalus mexicanus Gmelin) in North America since 1880. Journal of Biogeography 30(10):1593–1607. Close ; additional references in Distribution: Historical Changes to Distribution), and on methods of controlling the species (19 West, R. R., and J. H. Dunks (1969). Repelling Boat-tailed Grackles from sprouting corn with a carba-mate compound. Texas Journal of Science 21: 231–233. Close , 20 Rappole, J. H., A. H. Kane, R. H. Flores, A. R. Tipton, and N. Koerth (1989a). Seasonal variation in habitat use by Great-tailed Grackles in the Lower Rio Grande Valley. In Ninth Great Plains wildlife damage control workshop proceedings (A. J. Bjøgstad, D. W. Uresk and R. H. Hamre, Editors), USDA Forest Service General Technical Report RM-171. pp. 138–141. Close , 21 Rappole, J. H., A. R. Tipton, A. H. Kane, and R. H. Flores (1989b). Effects of grackle damage control techniques in citrus on nesting success of non-target species. In Ninth Great Plains wildlife damage control workshop proceedings (A. J. Bjøgstad, D. W. Uresk and R. H. Hamre, Editors), USDA Forest Service General Technical Report RM-171. pp. 129–132. Close , 22 Tipton, A. R., J. H. Rappole, A. H. Kane, R. H. Flores, and J. Hobbs (1989a). Use of DRC-1339 and PA-14 to control grackle populations in the Lower Rio Grande Valley. In Ninth Great Plains wildlife damage control workshop proceedings (A. J. Bjøgstad, D. W. Uresk and R. H. Hamre, Editors), USDA Forest Service General Technical Report RM-171. pp. 133–137. Close , 23 Tipton, A. R., J. H. Rappole, A. H. Kane, R. H. Flores, and D. B. Johnson (1989b). Use of monofilament line, reflective tape, beach-balls, and pyrotechnics for controlling grackle damage to citrus. In Ninth Great Plains wildlife damage control workshop proceedings (A. J. Bjøgstad, D. W. Uresk and R. H. Hamre, Editors), USDA Forest Service General Technical Report RM-171. pp. 126–128. Close , 24 Knittle, C. E., E. W. Schafer Jr., and K. A. Fagerstone (1990). Status of compound DRC-1339 registrations. Proceedings of the Vertebrate Pest Conference 14: 311–313. Close ).