Acorn woodpeckers are truly fascinating birds. For one, they don’t quite look like any other woodpecker species. But more than that, they have a complex social structure, unique cooperative breeding system, and remarkable habit of storing and protecting thousands of acorns. Living in large communal groups, these woodpeckers exhibit cooperative behaviors rarely seen in other bird species, with multiple breeding males and females working together to raise their young. Their intricate system of creating granaries, or storage holes in trees, to hoard acorns has captivated the attention of researchers and bird enthusiasts alike.
1. Acorn Woodpeckers Can Store Thousands Of Acorns In One Tree.
First things first, let’s find out why these woodpeckers were named after acorns. Not only do they eat acorns, but they have an impressive process for storing them. They choose dead tree limbs, fence posts, utility poles or even wooden barn walls and drill small holes. Acorns are collected from oak trees (or sometimes walnuts, pecans, pinyon pine nuts or hazelnuts) and stuffed tightly into the holes.
These woodpeckers wedge the nuts in so tight, that even hungry squirrels have a hard time getting them out. This acorn collection is called a granary, and can contain thousands upon thousands of acorns. These storage spaces ensure a steady supply of food during the winter.
2. Acorn Woodpeckers Work Together To Maintain Their Stash.
Acorn woodpeckers live in groups known as clans, which consist of 2 to 16 members. Within these clans, multiple breeding pairs and non-breeding helpers work together harmoniously to maintain their granary system. It’s an effort where everyone contributes by gathering and safeguarding acorns from thieves, like squirrels or other birds. In addition to drilling holes and collecting acorns, group members will survey the current store. Each hole is periodically checked, and acorns are moved to new holes if they become too lose.
3. Acorn Woodpeckers Have Unusual Plumage For Woodpeckers.
One of the most noticeable features of acorn woodpeckers is their striking appearance. While they have the common woodpecker colors of black, white and red, they are arranged quite differently. The most noticeable thing about them is their “clown face” of black, white and red with a light eye. Rather than facial stripes like many woodpeckers, they have solid blocks of color. Their back is solid black, with a black chest and long wispy dark stripes running down their white underparts.
4. Males And Females Have One Slight Difference.
At first glance you may not notice the difference between male and female acorn woodpeckers. To spot it, you have to look at their forehead. Males have white above the beak that is topped with a red crown. In females, there is a black section in-between the white above the beak and the red crown.
5. Acorns Aren’t The Only Food They Eat.
While they certainly spend a lot of time and effort on acorns and other nuts, they do have some diversity in their diet. They eat a lot of insects during the warmer months, including beetles, ants, and flying insects that they catch in the air. Hard-bodied insects may even be stored in tree bark. Fruits, flower nectar, lizards and seeds all round out their diet. They even sometimes consume tree sap like sapsuckers, working together to maintain a set of sap holes for many years.
6. Acorn woodpeckers nest in cavities.
When it comes to nesting, instead of building a traditional nest with the usual twigs and grass, acorn woodpeckers drill cavities into trees and wooden poles. As they dig, the wood shavings that naturally occur begin to line the bottom of the cavity, which then acts as the bedding material for the eggs.
Additionally, acorn woodpeckers reuse the same nesting hole year after year. Over time, a single tree can eventually resemble an apartment complex for woodpeckers with multiple holes accommodating families.
7. Acorn Woodpeckers Are Only Found In A Few States.
This species isn’t as widespread in the U.S. as other woodpeckers. They can be found along the west coast of Oregon and California, eastern Arizona, western New Mexico, and the Big Bend area of Texas. The rest of the population can be found in select areas of Mexico, Central America and even Columbia. Most stay in their local area year round, unless they are unable to store enough acorns to get through the winter. Due to their reliance on acorns, their habitat must either be in or very close to oak woodlands.
8. Acorn Woodpeckers Have Complex Social Structures.
Unlike many other bird species, acorn woodpeckers live in large, communal groups consisting of multiple breeding males and females, as well as non-breeding individuals. They work together to defend territories, raise young, and gather and store acorns, their primary food source. One of the most remarkable aspects of their social structure is their cooperative breeding system. There are males and females that breed, and those that don’t breed and are just “helpers”. The group mates together and works together to raise the group of young.
9. They Can Be Attracted To Yards.
If you happen to live near oak woodlands you may be able to attract these birds by hanging up suet feeders. They may even visit seed feeders, especially if you include some larger nuts.
Unfortunately, if they target the wood siding on your house, barn or shed as a good place to store acorns, they can be very hard to discourage. Some people have had luck with hanging strips of shiny ribbon or bird flashing, or using bird scare balloons. However if nothing works, switching to non-wooden siding may be the only option!
10. In the right habitat, they aren’t hard to find.
If you’re in the oak woodlands where they live, acorn woodpeckers shouldn’t be too hard to find. They like to perch at the top of bare trees, and have loud, squaking calls that sound a bit like parrots. In flight, their wing pattern helps give them away. Look for their black wing tips with a big patch of white, and their white belly and rump.
11. Females Destroy Each Others Eggs.
We mentioned their complicated social structure, and it gets even more complex in groups with several breeding females. All the egg laying females will put their eggs into one community nest. So one female will start, but then the next female ready to lay will destroy the eggs of the first female before she lays her own. This continues until all the breeding females in the group are ready to lay eggs. When all the females begin to lay at the same time, the eggs are kept.
12. acorn woodpeckers put on mating displays.
During the breeding season, acorn woodpeckers engage in displays to attract mates. These displays involve chases, rhythmic drumming, wing spreading, bowing, and impressive flight maneuvers that showcase their agility and strength.
13. Both sexes drum on drumming posts.
Both males and females engage in drumming, where they peck rapid-fire on a hard surface to create a loud, jackhammer-like sound. Drumming is used as a form of communication between woodpeckers. Acorn woodpeckers like to select dead, hollowed out tree limbs that produce a resonant sound. Favored limbs will be selected as drumming posts. Drumming occurs all year, but is most frequent during the spring to announce territory.
14. There are some concerns about the future of the acorn woodpecker.
While the population of acorn woodpeckers is not currently endangered, the loss of their habitats due to deforestation, slow oak forest regeneration, and urbanization poses a threat to these stunning birds. To ensure that acorn woodpeckers do not end up on the endangered species list, it is crucial to focus on conservation efforts that aim at preserving areas and protecting their habitats.
15. Acorn Woodpeckers are able to recognize past members of their group.
Research has shown that these impressive birds can recognize former members of their group years after they have left. Additionally, the acorn woodpecker uses vocalization to determine current group members.
16. They are seen as symbols of cooperation.
Acorn woodpeckers hold cultural significance for many different groups. They are seen as symbols of work, perseverance, and foresight, due to their planning and storing of acorns. In some Native American folklore, the acorn woodpecker has been seen as a symbol of cooperation and industriousness.
- “Individual Contributions to Cooperative Nest Care in The Acorn Woodpecker,” Ronald L. Mumme, Walter D. Koenig and Frank a. Pitelka, The Cooper Ornithological Society, 1990, sora.unm.ed
- “Acorn woodpeckers vocally discriminate current and former group members from nongroup members,” Oxford Academy, Michael A Pardo, Casey E Hayes, Eric L Walters, Walter D Koenig, September/October 2020, academic.oup.com
Amanda has a love for beekeeping and all things related to nature. She is also a small business owner, crafting various goods using the honey and beeswax harvested from her hives. Amanda resides in the tranquil mountains of West Virginia where she shares her home with her husband and beloved feline companions.