What is the difference between Grackles and boat-tailed grackles?

Grackles and boat-tailed grackles are two closely related species of birds in the Icteridae family. While they share some similarities, there are key differences between grackles and boat-tailed grackles in terms of their appearance, habitat, behavior, diet, and distribution.

Appearance

In terms of appearance, the most noticeable difference between grackles and boat-tailed grackles is in the tail. As their name suggests, boat-tailed grackles have a long, fan-shaped tail that resembles the back of a boat. Grackles have a more typical short, squared off tail.

Some key differences in appearance include:

• Size: Boat-tailed grackles are larger, measuring 18-24 inches compared to 11-13 inches for grackles.
• Tail: Boat-tailed grackles have a long keel-shaped tail, while grackles have a short squared off tail.
• Bill: Boat-tailed grackles have a longer, stouter bill than grackles.
• Colors: Male boat-tailed grackles have a deep purple-black body, while grackles are more iridescent black. Female boat-tailed grackles are brownish, while female grackles are darker gray-brown.
• Eyes: Boat-tailed grackles have bright yellow eyes compared to the pale yellow in grackles.

In terms of markings, the male boat-tailed grackle has glossy black plumage all over, while the male common grackle has more iridescent feathers showing purple, blue and bronze tints in good light. The female boat-tailed grackle is brownish-gray, and the female common grackle is darker grayish-brown.

Habitat

Boat-tailed grackles and common grackles also differ in their preferred habitats:

• Boat-tailed grackles are found in coastal areas, including saltwater marshes, mangroves, tidal flats and beaches.
• Grackles occupy more inland, freshwater wetlands and grasslands, along with agricultural areas, forests, and urban parks.

Boat-tailed grackles are rarely found more than 50 miles inland as they prefer coastal habitats. Their long tail helps them steer and maneuver over water surfaces where they forage.

Grackles have more generalized habitat preferences and can thrive in both natural and human-created environments like farmlands, pastures, and suburban areas.

Behavior

The behaviors of grackles and boat-tailed grackles also show some differences:

• Diet: Boat-tailed grackles forage on crustaceans, fish, and insects found in coastal waters. Grackles eat more terrestrial invertebrates, seeds, grains, fruits, and small vertebrates.
• Flocking: Boat-tailed grackles form massive flocks of 100,000+ birds in winter roosts. Grackle flocks are smaller, usually under 1,000 birds.
• Calls: Boat-tailed grackles’ calls are louder, more piercing and have a wider range of tones. Grackle calls are harsher and more abrasive.
• Nesting: Boat-tailed grackles nest in dense colonies in marsh vegetation. Grackles nest singly or in loose colonies in trees.

In terms of behavior, boat-tailed grackles are closely tied to the coastal marsh environment where they forage on aquatic prey. Grackles are more adaptable to a wider range of inland habitats.

Diet

The diets of grackles and boat-tailed grackles differ considerably:

• Boat-tailed grackles eat more marine-based foods including:
  • Fish
  • Shrimp
  • Crabs
  • Other crustaceans
  • Insects
  • Worms
• Grackles eat more land-based foods like:
  • Insects
  • Spiders
  • Snails
  • Earthworms
  • Small frogs and lizards
  • Grains
  • Seeds
  • Berries
  • Fruit
  • Bird eggs and nestlings
  • Carrion
  • Human food waste

Boat-tailed grackles are well adapted to utilize coastal food sources like small fish, crabs and shrimp. Grackles are generalist feeders and eat a wider variety of terrestrial invertebrates, plant material and human foods.

Distribution

In terms of distribution and range, grackles have a much wider distribution while boat-tailed grackles are limited to coastal regions:

• Boat-tailed grackles are found along the Atlantic and Gulf coasts from Connecticut to Texas, and along the Pacific coast from San Francisco Bay to central Mexico.
• Grackles are widespread across North America east of the Rocky Mountains from southern Canada to the Gulf of Mexico.

Here is a comparison of the range maps of each species:

As these maps illustrate, the boat-tailed grackle is restricted to coastal areas, while the common grackle occupies most of North America east of the Rockies.

Taxonomy

Grackles and boat-tailed grackles are closely related within the Icteridae family:

• Both are members of the genus Quiscalus
• However, they are separate species:
  • Common grackle: Quiscalus quiscula
  • Boat-tailed grackle: Quiscalus major

Some key differences in taxonomy:

So in summary, grackles and boat-tailed grackles diverged evolutionarily to become distinct species, but still share a close common ancestry in the genus Quiscalus.

Key identification differences

Here is a quick overview of some key identification points to distinguish grackles from boat-tailed grackles:

Remembering these key differences in size, tail shape, bill size, plumage coloration, eye color and habitat can help identify boat-tailed grackles vs common grackles.

Conclusion

In summary, while common grackles and boat-tailed grackles share some superficial similarities, they differ in a number of significant ways:

• Boat-tailed grackles are distinctly larger with a unique long, keel-shaped tail.
• Boat-tailed grackles inhabit coastal wetlands, while grackles occupy inland, freshwater habitats.
• Their diets also differ, with boat-tailed grackles consuming more fish and marine invertebrates.
• Grackles have a wider distribution across North America, while boat-tailed grackles are limited to the coasts.
• Their taxonomy indicates they are close relatives but separate species.

Paying attention to key identification features like tail shape, bill size, eye color and habitat can help distinguish these two closely related blackbird species.