Woodpeckers are known for their distinctive pecking against tree trunks. The reasons behind this behavior are varied, offering insight into the complex lives of these birds.
Hunting for Food
A primary reason woodpeckers peck trees is to locate and extract food. They forage for insects and their larvae residing beneath bark or within wood. Woodpeckers possess strong, chisel-shaped bills for excavating and long, barbed tongues to capture prey from deep crevices. They often listen for insects moving inside the wood or tap on the tree to identify hollow areas where grubs might be present.
Some species, such as sapsuckers, create rows of small holes in tree bark to access sap. These holes allow sap to flow out, attracting insects that sapsuckers also consume. While insects are a main dietary component, woodpeckers adapt their diet seasonally, incorporating fruits, nuts, or seeds when insect availability is low.
Building a Home
Woodpeckers also peck to excavate cavities within trees for nesting and roosting. These cavities provide shelter, protecting them from predators and harsh weather conditions. The excavated space serves as a secure location for raising their young, and wood chips created during excavation often form a bed for eggs.
These birds frequently select dead or decaying trees, or those with internal heart rot, because softer wood makes excavation easier while maintaining structural integrity. Each breeding season, many woodpecker species excavate a new nest cavity, though some may reuse successful sites. Abandoned woodpecker cavities are subsequently utilized by many other cavity-nesting birds and animals that cannot create their own holes.
Sending a Message
Distinct from pecking for food or shelter, woodpeckers engage in “drumming” as a form of communication. This involves rapid, rhythmic striking on resonant surfaces, including hollow trees, metal poles, or even gutters. Drumming serves to attract mates during the breeding season and to establish or defend their territory from rivals.
Both male and female woodpeckers participate in drumming, often increasing this activity in late winter and early spring. The tempo, rhythm, and duration of drumming patterns vary between species, serving as an auditory signal. This behavior is primarily about producing sound rather than creating holes, allowing their messages to travel across distances.
What Happens to the Tree?
The impact of woodpecker pecking on trees varies depending on the type of activity. For healthy, mature trees, the foraging activity of most woodpeckers is not harmful and can even be beneficial by removing wood-boring insect pests. These birds often target trees already infested with insects or those that are dead or dying.
However, extensive activity by sapsuckers can cause stress or damage to certain trees. Their repeated drilling for sap, particularly in thin-barked species like birch or maple, can create wounds that may allow entry for disease or fungi. While rare, continuous sapsucker feeding around a tree’s circumference can potentially girdle it, which disrupts nutrient flow and can lead to the tree’s decline.