Ants are one of the most abundant insect groups, making them a consistently available food source for many avian species. This commonality has led to specialized foraging behaviors and nutritional adaptations in birds that actively seek out ant colonies. The interaction highlights the adaptability of birds to exploit an insect that possesses potent chemical defenses. This predatory relationship is not limited to feeding, however, as some birds have also developed a unique, non-dietary use for their six-legged counterparts.
Primary Bird Species That Hunt Ants
Birds that consume ants often fall into two primary foraging groups. Ground foragers, such as the Northern Flicker, American Robin, and various warblers, target ants found on the soil surface or within subterranean nests. The Northern Flicker, a type of woodpecker, is a particularly dedicated ant specialist, with ants constituting up to 45% of its diet during the warmer months. This bird uses its specialized anatomy, including a tongue that can extend up to two inches beyond its bill tip, to probe deep into ant mounds and tunnels.
The Flicker hammers its bill into the soil to excavate ant colonies, a unique hunting method compared to other woodpecker species that typically bore into wood. Once the nest is exposed, the bird laps up hundreds of adults, larvae, and pupae using its sticky, saliva-coated tongue. Other ground-dwelling birds, like thrushes and starlings, are more opportunistic, snatching ants from trails or disturbed soil. The second group consists of wood and bark foragers, including many other woodpecker species, which often drill into rotten logs and trees to extract carpenter ants and their brood. These birds utilize their strong beaks to open galleries and a barbed tongue to pull insects from the internal structure of the wood.
Nutritional Value and Preferred Ant Stages
Ants appeal to birds due to their exceptional nutritional content, particularly during certain life stages. While adult ants provide protein, their hard chitinous exoskeletons can be difficult to digest. Birds therefore preferentially target the softer, nutrient-dense larval and pupal stages, often mistakenly referred to as “ant eggs.” These soft-bodied life stages contain a higher proportion of digestible protein and fat, making them an ideal energy source for growing nestlings and adult birds preparing for migration or breeding.
Flying ants, or alates, are especially prized, as they are reproductive forms emerging for nuptial flights. These forms are packed with energy reserves, sometimes containing over 50% fat by dry mass. During synchronous mass flights, alates can temporarily make up a significant majority of a bird’s diet, providing a concentrated burst of fat that is easily converted into metabolic water and stored energy.
This fat intake is also instrumental in the absorption of carotenoid pigments, which birds cannot synthesize themselves. Birds acquire the yellow, orange, and red coloration in their feathers by consuming carotenoids; efficient absorption is directly linked to the amount of fat in the diet. The presence of formic acid, which ants produce as a chemical defense, poses a digestive challenge. Some species must crush or rub ants to neutralize or expel this acid before swallowing, a behavior that transitions directly into the topic of anting. Other species, like the Northern Flicker, appear to have a high tolerance, consuming large quantities of acid-spraying ants without pre-treatment.
Anting A Non-Dietary Use for Ants
Beyond consumption, many bird species engage in anting, a maintenance behavior that uses ants for external purposes. This involves intentionally applying ants to the feathers or skin, leveraging the insect’s defensive chemicals. The most common form is active anting, where a bird grasps a single ant in its bill and rubs it repeatedly over its plumage, particularly on the flight and tail feathers.
A less common method is passive anting, where the bird lies directly on an ant hill and allows the insects to swarm and crawl through its feathers. The primary theory behind this behavior is pest control, utilizing the formic acid secreted by ant species, most notably those from the Formicinae subfamily. Formic acid acts as a natural insecticide and fungicide, potentially deterring feather mites and lice or inhibiting the growth of bacteria that degrade plumage.
Anting is also hypothesized to serve a pre-ingestion function (the food-preparation hypothesis). By irritating the ant and causing it to spray its defensive acid onto the feathers, the bird effectively “detoxifies” the insect, making it more palatable before consumption. Regardless of the exact purpose, this widespread behavior across over 200 bird species demonstrates a complex exploitation of the ant’s chemical arsenal for hygiene or culinary preparation.