Different birds gather food in different ways depending on their diets and bill shapes, allowing each species to take advantage of unique foods within the same habitat and range without strong competition. Understanding how birds forage and noticing subtle variations between feeding birds can help birders better identify species by their behavior.
Types of Foraging
Foraging is the simple act of gathering food, either for immediate consumption or future storage. This act is anything but simple, however, and bird bills are highly evolved with different shapes and lengths to gather preferred foods best. Bird tongues, senses, talons, and flight abilities also play great roles in how they forage, and there are many different ways birds can gather food.
- Scratching: This involves birds using one foot or both feet simultaneously to remove or loosen debris from the ground to reveal seeds, bugs, or other food. This is a common foraging behavior for many ground-feeding birds, including sparrows, grouse, quail, and towhees.
- Gleaning: Birds use careful, meticulous picking of food from a surface such as a tree, branch, grass, or leaves. Nuthatches, chickadees, and tits glean in trees; warblers often glean from leaves, and thrushes often glean from the ground.
- Hawking: With hawking, birds snatch food, usually insects, with the bill while in flight and consuming it without perching. This is the most prevalent feeding method for swifts, swallows, martins, and nighthawks, but many warblers and flycatchers also practice hawking.
- Sallying: For sallying, birds catch insects in the air but return to a perch to feed. They often return to the same perch between several consecutive feedings. This is a common foraging behavior for many flycatchers and rollers.
- Scanning: Birds watch an area carefully for prey before suddenly attacking to pursue it. This is common for raptors that soar or hover over an area while looking for prey, and when they find it, their dive is swift and sudden to take it by surprise.
- Probing: Probing involves Inserting the bill into a crevice or beneath the ground's surface to seek out and extract food. This is common on beaches with sandpipers and other shorebirds, while woodpeckers probe trees in forests and hummingbirds probe flowers in gardens.
- Lunging: For lunging, birds dart quickly after prey to strike at it rapidly, often with pauses between hunting forays. This is typical foraging behavior for roadrunners and plovers, as well as for wading birds such as herons.
- Dabbling: Birds tip up while swimming to immerse the head, neck, and upper body to get at aquatic foods such as algae or other vegetation. Many ducks and geese use this behavior in shallow water.
- Dipping: With dipping, birds dip briefly into the water for food that is often seen rather than felt. Submersion may be partially or completely under the water, and gulls and dippers are experts at dipping while feeding.
- Diving: For diving, birds swim completely under the water to forage on vegetation or pursue prey such as fish or crustaceans. Mergansers and several types of ducks forage by diving, as do loons, anhingas, and penguins.
- Plunge Diving: Plunge diving involves diving into the water from a significant height to capture prey beneath the surface. This may be done bill-first, such as with pelicans or kingfishers, or feet-first, as with ospreys and eagles. Some raptors, such as the great gray owl, plunge dive into the snow while hunting.
- Skimming: With skimming, birds feel along the surface of the water to capture prey, such as insects or fish, at or just below the surface. Flamingos, avocets, and spoonbills are examples of surface-skimming birds, while more specialized birds such as black skimmers skim in flight.
Birds are opportunistic, intelligent feeders and often use a variety of feeding techniques, adapting their methods to best suit the current conditions of their habitat and prey. By understanding these major types of foraging, birders can better understand the behaviors they observe.
Other Foraging Behaviors to Observe
To feed successfully, birds not only use different foraging techniques but an entire range of related behaviors that help ensure successful feeding and an abundant diet. When you see foraging birds, watch for these other fascinating behaviors:
- Caching: Many birds store food for later use, creating stockpiles they can rely on if food sources become scarce. This is particularly noticeable in northern habitats and with species such as woodpeckers and jays that remain in the same range year-round.
- Lookouts: A flock of birds that forages together often has one or more lookout birds that keep sharp eyes trained for predators or other dangers. Flocks of geese and gulls often have multiple lookouts.
- Changing Techniques: Birds that glean for insects in spring and summer will then switch to scratching through leaf litter for seeds in fall and winter. This indicates seasonal changes in their diet as they adapt to the most abundant food sources at different times of the year.
- Mixed Flocks: Mixed flocks often forage in the same area, and each species has different foraging tactics. A winter flock, for example, may include chickadees gleaning from branches, nuthatches probing down tree trunks, and creepers probing up tree trunks simultaneously.
- Trapping: Some birds use traps to catch prey, even if they don't precisely set the traps themselves. Hummingbirds, for example, pluck insects from spiderwebs. Some birds have even been observed using bait, such as herons using bread from picnic areas to entice fish into hunting range.
- Casting Pellets: Birds that consume large quantities of inedible material, such as exoskeletons from insects or fur and bones from the prey, regurgitate pellets to rid their systems of that indigestible material. Ornithologists often dissect those pellets to analyze bird diets and popular food sources.
Gaining familiarity with how birds forage and recognizing various foraging techniques can help birders better identify different birds in the field and learn to appreciate their diverse behavior even more thoroughly.