What do Woodpeckers Eat and how do they find their food?

Woodpeckers primarily consume insects, particularly wood-boring invertebrates. They exhibit adaptability in their diet, incorporating fruit, nuts, seeds, and sap based on seasonal availability. Their foraging techniques include visual searching, probing, auditory cues, flycatching, ground foraging, and caching behavior.

Pileated Woodpecker (Dryocopus pileatus) with wood-boring beetle larvae.

Woodpeckers are Primarily Insectivorous

Woodpeckers are generally known as insectivores, with their diet largely consisting of insects and other invertebrates found in trees. They are particularly adept at extracting wood-boring insects, using their strong bills to excavate holes and their long, barbed tongues to capture prey.

Seasonal Adaptations

While insects are the mainstay of their diet, woodpeckers are flexible in their food choices, especially during different seasons.

  • Fruit and Nuts: During the non-breeding season, some species, such as flickers, incorporate fruit and nuts into their diet. This shift towards plant-based food sources likely occurs due to the reduced availability of insects during colder months.
  • Seeds: Several non-migratory species add seeds to their winter diet, further demonstrating their adaptability to seasonal changes in food availability.
  • Sap: Sapsuckers, as their name suggests, are specialized for feeding on tree sap. They drill wells in trees to access the sap and also consume insects trapped in the sap.
Downy Woodpecker (Picoides pubescens) preparing to consume a berry.

Woodpecker’s Unique Foraging Techniques

Woodpeckers employ various methods to find and secure their food:

  • Visual Searching and Probing: They locate prey on bark and in crevices by visually searching and probing with their tongues.
  • Auditory Cues: Woodpeckers can also detect prey within wood by listening for sounds, indicating where excavation might be fruitful.
  • Flycatching: Some woodpeckers and sapsuckers consistently engage in flycatching, catching insects in midair.
  • Ground Foraging: A few species, like Flickers, have adapted to foraging on the ground.

Caching Behavior

Several North American woodpeckers, including the Acorn Woodpecker, Red-headed Woodpecker, and Red-bellied Woodpecker, exhibit food caching behavior, storing food items for later consumption. Acorns are the most common cached item, but other nuts and insects are also stored.

Role of the woodpeckers foraging techniques in forest ecosystems

The dietary adaptations and foraging techniques of woodpeckers demonstrate their important role in forest ecosystems. By consuming wood-boring insects, they contribute to the health of trees. Additionally, their food caching behavior can aid in seed dispersal, further impacting the plant communities within their habitat.

Most woodpeckers chisels and drill dead wood and bark as part of their foraging technique. Some combine flycatching insects and ground digging for ants (Flickers).

Locating and Extracting Prey: Woodpecker Ingenuity

Woodpeckers utilize a combination of sensory cues and specialized adaptations to locate and extract insects hidden within trees. They are like skilled detectives, employing multiple tools to uncover their quarry.

Finding Insects:

  • Visual Searching: Woodpeckers visually inspect bark surfaces and crevices, looking for signs of insect activity, such as small holes or irregularities in the bark. Think of them meticulously scanning the tree’s surface for clues.
  • Probing: They also use their tongues to probe into crevices and under bark, exploring potential hiding places for insects. This is akin to a detective using a probe to search for evidence in tight spaces.
  • Auditory Cues: Perhaps most remarkably, woodpeckers possess the ability to hear insects within the wood.
    They can detect the subtle sounds of larvae feeding, scraping wood, or moving beneath the bark, allowing them to pinpoint the location of their prey. Imagine having such acute hearing that you can hear termites munching inside a wooden beam!

Extracting Insects:

Once an insect has been located, woodpeckers employ their specialized anatomy to extract it.

  • Powerful Bills: Their strong, chisel-shaped bills are perfectly adapted for excavating wood. They can hammer into the wood with remarkable force, creating openings to access their prey. Their bills act like miniature jackhammers, breaking through the wood’s defenses.
  • Long, Barbed Tongues: Woodpeckers possess exceptionally long tongues, often exceeding the length of their bills. These tongues are also barbed and sticky, allowing them to effectively capture and extract insects from deep within the wood crevices and tunnels. This is similar to a fisherman using a barbed hook to snag a fish from its hiding place.
Finding and extracting their prey often requires contortions and uso of the extendable tongue, as shown by this Red-bellied Woodpecker (Melanerpes carolinus) Photo: Wildreturn.

Tongue Structure and Mechanics:

The incredible extensibility of the woodpecker’s tongue is due to its unique skeletal structure.

  • Hyoid Apparatus: All birds have a hyoid apparatus, a set of bones that supports the tongue. However, in woodpeckers, this apparatus is highly modified.
  • Elongated Hyoid Horns: The hyoid apparatus extends into two long, slender “horns” that wrap around the skull, passing beneath the jaw bone and often even encircling the eye socket, depending on the species. These elongated horns act like springs, storing energy and allowing the tongue to be rapidly projected outward.
  • Muscular Control: When the woodpecker wants to extend its tongue, muscles contract, pulling the hyoid horns forward, which in turn thrusts the tongue outward with great speed and precision.

The combination of powerful bills, extensible tongues, and acute hearing makes woodpeckers highly effective predators of wood-boring insects. 

Sapsucker Foraging: A Specialized Approach

While all woodpeckers are known for their insect-extracting abilities, sapsuckers stand out with their unique foraging behavior centered around tree sap. Sapsuckers’ feeding strategy distinguishes them from other woodpeckers:

  • Sap as a Primary Food Source: Unlike other woodpeckers that primarily consume insects, sapsuckers have evolved to rely heavily on tree sap as a key component of their diet. Their name reflects this specialization, emphasizing their dependence on this sugary, nutrient-rich liquid.
  • Well Drilling: Sapsuckers are known for their distinctive well-drilling behavior. They create rows of small, shallow holes, called “sapsucker wells,” in the bark of trees. These wells allow access to the sap flowing in the tree’s phloem, the tissue responsible for transporting sugars. Imagine them as tiny, well-organized construction crews, meticulously creating access points to the tree’s sweet reserves.
  • Sap Consumption: Sapsuckers use their specialized tongues to lap up the sap that oozes from these wells. Their tongues are long and brush-tipped, enabling them to efficiently collect the flowing sap.
  • Insect Trapping: The sap wells also serve as traps for insects attracted to the sugary sap. Sapsuckers take advantage of this, consuming the insects caught in the sticky sap along with the sap itself. They essentially create their own insect-catching stations.
  • Learning from Adults: Interestingly, young sapsuckers learn the art of well-drilling by observing adults. This suggests that there’s a learned component to their foraging behavior, passed down through generations.

Sapsuckers drill rows of small, shallow holes, called “sapsucker wells,” in the bark of trees. These wells allow access to the sap flowing rich in sugars. Sap attracts other birds as well as insects that often get entrapped in the sap; adding to the nutritive value of the sap.

The impact of sapsucker foraging extends beyond their own nutritional needs.

  • Ecological Effects: Sapsucker wells create a valuable resource for other animals in the forest. Various species, including mammals, insects, other woodpeckers, orioles, hummingbirds, and warblers, also feed at these sap wells. They create a sort of “forest buffet,” providing nourishment for a diverse array of creatures.
  • Distinctive Scars: The wells drilled by sapsuckers leave characteristic scars on tree trunks that can persist for many years. These markings serve as a lasting record of the sapsucker’s presence, providing clues to researchers studying their distribution and habitat use.

Sapsuckers’ unique foraging behavior have not only evolved the physical tools but also the behavioral strategies to effectively exploit tree sap, contributing to the intricate web of interactions within forest ecosystems.

Woodpecker Caching: Why and how do they do it?

Woodpeckers, particularly North American species, exhibit a remarkable behavior known as food caching. This practice involves storing food, primarily acorns and nuts, for future consumption, especially during periods of scarcity. 

Caching provides a survival advantage, particularly for non-migratory species, by ensuring a reliable food supply during harsh winter conditions.

Reasons for Caching:

  • Seasonal Food Shortages: Woodpeckers primarily rely on insects and other invertebrates as their main food source. However, the availability of these food sources can fluctuate significantly throughout the year, particularly during winter when insect populations decline.

    Caching food allows woodpeckers to create a reserve of food to tide them over during these periods of scarcity.
  • Survival Advantage: This behavior provides a significant survival advantage, especially for non-migratory species that remain in their territories year-round. Having a readily available supply of stored food allows them to maintain energy levels and survive harsh winter conditions.

Types of Food Cached:

The types of food commonly cached by woodpeckers include:

  • Acorns: Acorns are the most frequently cached food item, likely due to their abundance and nutritional value.
  • Other Nuts: Woodpeckers also store other locally available nuts, including pinyon pine nuts, beechnuts, almonds, and pecans.
  • Insects: While acorns and nuts are the primary cached items, woodpeckers are also known to cache insects, providing a source of protein during times when insects are less readily available.

Caching Techniques:

Woodpeckers employ various methods for storing their cached food:

  • Crevices and Bark: Most species, with the exception of the Acorn Woodpecker, store food in natural crevices in trees, cracks in bark, or under loose bark.
  • Acorn Woodpecker Granaries: The Acorn Woodpecker, however, exhibits a unique and highly specialized caching behavior. This species drills holes specifically for food storage in trees, telephone poles, or fence posts. These storage sites are referred to as “granaries,” and they can hold vast quantities of acorns. One study documented over 60,000 acorns in a single granary.

Acorn Woodpecker and Cooperative Breeding:

The Acorn Woodpecker’s caching behavior is closely tied to its social structure. This species practices cooperative breeding, with groups of birds sharing the responsibility of filling, defending, and utilizing the granaries. This communal approach to food storage ensures a more reliable food supply for the entire group, enhancing their chances of survival.

Evolutionary Significance:

Woodpecker food caching behavior is thought to have evolved from a more basic behavior:

  • Lodging Food Items: Woodpeckers often wedge hard food items, such as nuts, into crevices to hold them in place while they pound them open with their bills. This behavior of lodging food items may have served as a precursor to caching, gradually evolving into the more complex practice of storing food for future consumption.

The food caching behavior of woodpeckers highlights their adaptability. By creating reserves of food during times of plenty, they increase their chances of surviving seasonal fluctuations in food availability.

The Unique Social System and Granaries of Acorn Woodpeckers

Acorn Woodpeckers (Melanerpes formicivorus) are known for their unique social system and specialized food storage habits, which are closely intertwined.

Acorn woodpecker (Melanerpes formicivorus) and granary. Photo: Ingrid Taylar.

Cooperative Breeding

Unlike most woodpecker species that form monogamous pairs, Acorn Woodpeckers live in social groups that practice cooperative breeding, where multiple males and females breed and raise young together. These groups can include up to 12 individuals, with multiple females laying eggs in a single nest

However, competition exists even within cooperative groups. Females may remove the eggs of other females to improve the hatching success of their own eggs. This behavior ensures that only a manageable number of eggs are incubated at a time, leading to better survival rates for the chicks.

Young birds from previous years often stay with the group, assisting in territory defense and raising the next generation of offspring. This cooperative breeding system provides a number of benefits, including:

  • Increased reproductive success for the group as a whole, as more adults are available to help raise young.
  • Enhanced survival for individual birds, especially during times of food scarcity or when facing threats from predators.
  • Opportunities for young birds to learn valuable skills from experienced adults before establishing their own territories.

Granaries: Communal Food Storage

The cooperative breeding system of Acorn Woodpeckers is closely linked to their remarkable food storage habits. Unlike other woodpeckers that might occasionally cache food, Acorn Woodpeckers are dedicated hoarders, creating elaborate communal storage sites called granaries.

  • Specialized Construction: These granaries are not simply natural crevices or spaces under bark. Acorn Woodpeckers actively drill holes in trees, telephone poles, or fence posts specifically to store acorns. They meticulously select trees or structures with suitable surfaces for drilling and acorn storage.
  • Massive Scale: Granaries can be incredibly extensive, containing thousands of acorns. A study about Acorn Woodpecker granaries reported a single granary holding over 60,000 acorns. This impressive feat of food storage reflects the cooperative nature of Acorn Woodpecker groups.
  • Group Defense: The entire group works together to fill, maintain, and defend their granaries. This cooperative effort ensures a reliable food supply for all members of the group, particularly during the winter months when other food sources are scarce.
  • Granaries and Acorn Availability: The Acorn Woodpeckers’ reliance on their granaries is so significant that they will even abandon their territories and wander in search of new food sources if their stored acorns run out. This highlights the critical role that granaries play in their survival.

The Acorn Woodpecker’s unique combination of cooperative breeding and communal food storage makes them a fascinating example of social complexity and adaptation in the bird world. Their granaries are a testament to their cooperative nature and their remarkable ability to plan for future needs.

In conclusion, woodpeckers are highly specialized and adaptable foragers, playing vital roles in forest ecosystems through their insect consumption and food caching behaviors. Their diverse feeding strategies and unique adaptations demonstrate their remarkable ingenuity in finding and securing food resources.

See also: Regional Guides to the Woodpeckers of North America

Additional resources:

References and Sources:

  • Allaboutbirds.org)
  • Gill, Frank B., 1994. Ornithology – 2nd Edition, W. H. Freeman and Company.
  • The Sibley Guide to Bird Life and Behavior, 2001. Chris Elphick, John Dunning, and David Sibley (eds). Alfred A. Knopf, New York.

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