Measurements
Both Sexes
- Length
- 10.2–14.6 in
26–37 cm - Wingspan
- 15.4–19.7 in
39–50 cm - Weight
- 3.3–8.4 oz
93–239 g
Relative Size
- Smaller than a Fish Crow; larger than a Common Grackle.
Other Names
- Quiscale des marais (French)
- Tordo cola ancha (Spanish)
Cool Facts
- Fledglings that fall into the water can swim well for short distances, using their wings as paddles.
- The Boat-tailed Grackle has an odd mating system, called “harem defense polygyny,” that has much in common with deer and other big game. Females cluster their nests in a small area safe from predators, and males compete to see which one gets to defend and mate with the entire colony. But it’s not as simple as it may seem: though a colony’s dominant male mates far more often with the females, DNA fingerprinting shows that only about a quarter of the young are actually his. The remainder are fathered by males who the females mate with while away from the colony.
- The Boat-tailed Grackle was formally described in 1819 by the French ornithologist Louis Jean Pierre Vieillot, from a specimen collected in New Orleans, Louisiana.
- The oldest Boat-tailed Grackle on record was nearly 14 years old when it was caught and released by a South Carolina bird bander in 2003.
Habitat
Marsh
Boat-tailed Grackles breed abundantly in salt and freshwater marshes along the Atlantic and Gulf coasts. They are closely associated with saltwater and are rarely found more than about 30 miles from saltwater except in the Florida peninsula, where they occur across its breadth. Main breeding habitats include saltmarsh; marshes along rivers, lakes, impoundments, or ponds; and nearby upland habitats. They forage in city streets and plazas, cultivated fields, stockyards, open beaches, and saltmarshes. They stay in the same types of habitats during the nonbreeding season.
Food
Omnivore
Boat-tailed Grackles eat arthropods, crustaceans, mollusks, frogs, turtles, lizards, grain, seeds, fruit, and tubers. Inveterate scavengers and pirates, they also take food from humans, domestic animals, and other birds. They usually forage out in the open, in a wide variety of habitats that include floating mats, mudflats, beaches, roadsides, parking lots, dumps, cultivated fields, and cattle feedlots. They walk slowly over the ground or in shallow water, pecking or probing at soil, litter, or low vegetation. They often overturn debris, stones, and shells with their bills. In aquatic habitats they stand still and cock their heads to watch the water with one eye, then plunge their heads below the surface. They can pry open mussel shells and eat snails by forcing an opening between the tissue and the shell. Boat-tailed Grackles often dunk foods like bread, rice, and dog food in water before eating them.
Nesting
Nesting Facts
- Clutch Size
- 1–5 eggs
- Number of Broods
- 1-2 broods
- Egg Length
- 1.1–1.5 in
2.7–3.8 cm - Egg Width
- 0.7–0.9 in
1.9–2.4 cm - Incubation Period
- 13 days
- Nestling Period
- 13 days
- Egg Description
- Light blue, covered with brown and black scrawls.
- Condition at Hatching
- Partly covered with creamy tan down.
Nest Description
The female builds the nest by herself in about 8 days, starting with a shallow platform of long, coarse grass stems, leaves, or Spanish moss. On top of the platform she weaves an outer cup of grass stems and leaves around branches, and then adds an inner layer of wet mud and debris to create an inner cup about 3.5 inches across and just as deep. Finally she lines the nest with fine materials like pine needles and grass stems.
Nest Placement
Tree
Boat-tailed Grackles nest in cattails and other grasses of freshwater or brackish marshes, about 2 feet off the ground. Females choose an area secure from ground predators and out of the reach of floodwaters. Especially in the northern part of their range, they may nest in isolated trees or bushes near water, up to 13 feet off the ground. Nest trees include live oak, white mangrove, wax myrtle, redcedar, water oak, and cabbage palm.
Behavior
Ground Forager
Gregarious Boat-tailed Grackles roost communally in tall grasses all year round. During the breeding season, the nesting females stay on their nests, but males and nonbreeding females leave colonies to join roosts that may include other blackbirds and European Starlings. The harem mating system of these grackles is unique to birds in North America, though it’s shared by oropendolas of the American tropics. Individual males defend clusters of nesting females from other males. Only the high-ranked males, having established their status through displays and vigorous fights, get to mate in the colony, although DNA evidence indicates other males manage to mate with females away from the colonies. Boat-tailed Grackles often take advantage of humans for food and predator protection, through behavior like foraging in dumpsters and forming colonies on traffic islands. Their most serious predators are the yellow rat snakes that attack their nests, but they are also preyed upon by black rats, Norway rats, rice rats, alligators, and Purple Gallinules.
Conservation
Least Concern
Boat-tailed Grackles are fairly common within their restricted range, and their populations are stable. Their strict habitat use of marshes along a very narrow coastal range puts them at risk from coastal development, which is intense in many areas. Researchers recommend monitoring their numbers and maintaining coastal impoundments for nesting birds. Some people consider Boat-tailed Grackles to be pests because they are gregarious and noisy, their droppings are messy, and they may eat pet food, rice crops, and fruit-tree crops. People sometimes try to deter grackles and other blackbirds by shooting at them, or poisoning them (although Boat-tailed Grackles are legally protected under the Migratory Bird Treaty Act of 1918). In some places farmers have adopted less harmful methods of protecting their crops, including cutting down brushy roost sites, harvesting while grackles are busy nesting, and scaring the birds away with balloons or explosions.
Credits
- Post, W., J. P. Poston, and G. T. Bancroft. 1996. Boat-tailed Grackle (Quiscalus major). In The Birds of North America, No. 271 (A. Poole and F. Gill, eds.). The Birds of North America Online, Ithaca, New York.
- Bancroft, G.T. 1984. Growth and sexual dimorphism of the Boat-tailed Grackle, The Condor 86: 423-432. The Cooper Ornithological Society. [PDF]
- USGS Patuxent Wildlife Research Center. 2011. Longevity Records of North American Birds.
Migration
Year-round resident. Most individuals spend their lives within about 10 miles of their birthplace. The longest recorded movement comes from a second-year male that was banded in Charleston, South Carolina, and recovered in Daytona Beach, Florida, about 320 miles away by land.
Backyard Tips
Boat-tailed Grackles eat sunflower seeds, sorghum, millet, corn, and other bird seeds from feeders, particularly platform feeders.
Find This Bird
To see Boat-tailed Grackles, head to the southeastern or Gulf Coast and look for long-tailed black birds around marsh edges, boat launches, and parks. They often walk around boldly on long legs with their tails cocked up, searching for food. It is also common to see Boat-tailed Grackles perched on roadside utility wires. If you still can’t find one, head to a fast food restaurant in a beach town and scout around for discarded French fries—you’re almost sure to find grackles there.