The common grackle (Quiscalus quiscula) is a widespread member of the blackbird family (Icteridae) across North America east of the Rocky Mountains. This species thrives in diverse environments, from marshes to urban centers, due to its dietary flexibility. Grackles are classic omnivores, meaning their diet shifts dramatically based on season and resource availability. Their opportunistic feeding habits allow them to exploit nearly any food source they encounter.
Plant-Based Staples and Seasonal Shifts
Plant matter forms a substantial part of the grackle’s diet, especially outside the breeding season when high-protein food is less critical. As granivores, they consume a wide range of seeds and grains throughout the year, targeting crops like corn (during sprouting) and small grains such as rice and wheat. Grackles have a sharp, hard keel on the upper palate of their bill, which functions like a saw to score and open tough food items. This allows them to process hard mast, such as acorns, which are often too difficult for other birds to crack. In late summer and fall, their diet shifts to include soft mast like berries and fruits, providing carbohydrates necessary for migration and winter survival when insects are scarce.
Essential Animal Protein Sources
Animal matter is an indispensable component of the grackle diet, making up a quarter to half of their food intake during the summer months. This high-protein intake is important during the nesting period when females are laying eggs and parents are feeding young. They consume a wide variety of invertebrates, including beetles, grasshoppers, spiders, caterpillars, and larvae, which they actively forage for on the ground. Beyond insects, grackles capture small vertebrates and aquatic life, wading in shallow water to catch minnows, crayfish, or amphibians. They are also opportunistic predators of other birds’ nests, consuming eggs and nestlings, and will hunt small mammals such as mice, especially following agricultural plowing.
Foraging Tactics and Urban Scavenging
Grackles employ several behaviors to acquire their varied diet, demonstrating their adaptability as foragers. They often walk along the ground, flipping over leaves and debris with their bills to uncover hidden insects and spiders. In aquatic environments, they wade in to snatch prey, and they have been observed stealing food from the beaks of other birds. A unique behavior is “anting,” where the bird allows ants to crawl over its feathers; this utilizes the formic acid secreted by the ants as a natural insecticide or parasite repellent. In human-dominated landscapes, grackles become effective scavengers, frequently targeting garbage receptacles, outdoor pet food, and leftovers at picnic areas.