The Common Grackle, an often-seen bird in much of east and north Texas, is the smallest of the three grackle species breeding in this state. This medium-sized bird is larger than other blackbirds found in Texas, and the combination of an all-black plumage, yellow eye, and longer, but not conspicuously long tail, separates Common Grackle males from others of its family in Texas. Females are duller and juveniles are dull brown.
These omnivorous and opportunistic birds eat a wide variety of foods: insects, vegetable matter and even young birds or eggs of smaller species. (Peer and Bollinger 1997).
DISTRIBUTION. During the 1987-1992 field work for the TBBA project volunteers found confirmed or probable breeding evidence for Common Grackle throughout the state except for the Trans-Pecos, western Edwards Plateau, South Texas Brush Country and Coastal Sand Plain areas (as defined by Lockwood and Freeman 2004). Northeast and north central Texas and the northern Panhandle had the densest concentration of records. Oberholser’s (1974) map shows many fewer records for the Panhandle, but is otherwise similar.
In winter birds moving south from areas to the north augment breeding populations. (Christmas Bird Count data; Sauer et al. 1996).
Outside Texas, Common Grackles breed from northwest Alberta east across southern Canada to the southwest tip of Newfoundland and south to the Gulf Coast. In winter northern breeders move south and east of a line from southern Minnesota through the lower Great Lakes to the central Maine coast and east of a line from southern Minnesota to north-central Texas (Peer and Bollinger 1997).
SEASONAL OCCURRENCE. Oberholser (1974) indicated abundance of Common Grackle is higher in Texas in winter as migrants from further north add to the resident population.
The breeding season extends from early March to August with egg dates from April 12 to June 17 (Oberholser 1974). TBBA field workers augmented this data, finding pairs building nests from April 24 to June 10, active around nests from May 14 to June 12, feeding nestlings or fledglings from April 6 to July 16, recently fledged young present from March 29 to August 17, adults carrying fecal sacs from March 30 to July 28, a nest with eggs on July 30, and nests with young from June 7 to July 20. May and June had the highest number of confirmed breeding reports.
BREEDING HABITAT. The elevational range in Texas of Common Grackles is from near sea level to 975 m (3200ft). Within this range the species is primarily found in forested regions or partially cut- over wooded areas. In the northeast, Pineywoods and bottom lands of the Big Thicket have the highest densities of Common Grackles. The species is also most common in towns, pastures and fields in areas where the other two grackle species are rare or absent. The Great-tailed Grackle (Q. mexicanus) prefers more open country with scattered trees, while the Boat-tailed Grackle
(Q. major) is a bird of fresh and salt water marshes near the coast (Oberholser 1974).
Common Grackles usually nest in small colonies of 20-30 pairs. Common nest sites are small tree, shrubs, roadside plantings, natural cavities, ledges, and cattail marshes. The nest is a bulky cup, made of forbs, Spanish moss, and debris, often reinforced with mud. The outside diameter is 18-23 cm (7-9 in), height 13-20 cm (5-8 in), and inner diameter 10-11 cm (4-4.5 in).
Average clutch size is about 5 eggs (range 1-7); Common Grackles nay re-nest after loss of the first clutch but second successful clutches have not been reported. The female incubates the pale blue or green eggs for 11.5-14 (mean 13.5) days. Cowbird rarely parasitize this species. Young birds fledge 10-17 days after hatching. (Harrison 1979, Peer and Bollinger 1997).
STATUS. Common Grackle is a common to locally uncommon breeder in the eastern two-thirds of Texas west through the High Plains and the central Edwards Plateau and south to the Guadalupe River drainage. From mid-September to late March, the population is abundant in the eastern third of the state, becoming increasingly less common westward (Lockwood and Freeman 2004).
Average counts on most Breeding Bird Survey (BBS) routes in the eastern two-thirds of Texas are 4-10 Common Grackles per 40 km (25 mi) route (Sauer et al. 2004).
Winter numbers, as measured by Christmas Bird Counts within 25 km (15 mi) diameter circles, range from >100 per count in the eastern third of Texas, decreasing to the west and south (Sauer et al. 1996).
Data from the 125 BBS routes in Texas on which Common Grackle has been detected produce a 95% confidence interval of -1.7 to 1.9% change per year (there is a 95% probability that the actual value will fall within these two figures). For the total range of Common Grackle in the United States and Canada, the species shows a statistically significant decline of 1.2% per year. Comparison of the 125 routes on which the Common Grackle was found in Texas with the 2765 for the total BBS area, suggests that the Texas breeding area makes up only about 5% of its total breeding area (Sauer et al. 2004).
Common Grackle numbers and range may suffer in future years from competition with the larger Great-tailed Grackle, whose range has expanded greatly east of the Rocky Mountains in recent years. Because these two species prefer different habitats, Common Grackle will continue to be found in the more heavily wooded areas of Texas, being displaced primarily in more open habitats preferred by Great-tailed Grackle, but marginal for Common Grackle. Text by Robert C. Tweit (2005).
Harrison, H. H. 1979. A field guide to western birds’ nests. Houghton Mifflin, Boston, MA.
Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.
Oberholser, H. C. 1974. The bird life of Texas, Vol. 2. University of Texas Press, Austin.
Peer, B. D., and E. K. Bollinger. 1997. Common Grackle (Quiscalus). In The Birds of North America, No. 271 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Sauer, J. R., S. Schwartz, and B. Hoover. 1996. The Christmas Bird Count Home Page, Version 95.1. Patuxent Wildlife Research Center, Laurel MD (Web site, http://www.mbr-pwrc.usgs.gov/bbs/cbc).
Sauer, J. R., J. E. Hines, and J. Fallon. 2004. The North American Breeding Bird Survey, results and analysis 1966-2003. Version 2004.1. USGS Patuxent Wildlife Research Center, Laurel MD (Web site, http://www.mbr-pwrc.usgs.gov/bbs).