why do woodpeckers make holes in trees

Now is the time the trees begin to take a hammering as great spotted woodpeckers establish their territories. These starling-sized black and white birds don t have a song to advertise ownership of their chosen patch of woodland, so they make themselves known by drumming on dead trees with their powerful bills. It s a dramatic sound and some creative individuals will use other surfaces such as the metal plates on telegraph poles to create an even louder salvo. One bird even used a metal public address tannoy at a racecourse. Woodpeckers ought to get headaches as a result of those hammering blows; they don t because their skulls are cushioned by a matrix of minute pockets of air, supported by strengthened bone tissue. This natural shock absorber allows them not only to drum, but to excavate nest holes and peck in dead wood for insects. They re not averse to taking the eggs and nestlings of tits and other hole-nesting birds. Drumming is most intense between late January and April and you are more likely to hear it at this time of year. We take it for granted that the woodpecker makes the sound by striking the surface of a resonating object, but as recently as the 1940s, some people still maintained that the bird made the sounds vocally. The argument was finally resolved in 1943 when a birdwatcher named Norman Pullen settled the matter by placing a microphone inside a tree and watched the woodpecker as its bill struck the bark: the sounds matched the striking exactly.


Great spotted woodpecker populations have increased rapidly over the last 40 years, more than doubling their numbers. They have even crossed the Irish Sea, breeding in Northern Ireland in 2006 and the Republic of Ireland in 2009, for the first time. Garden feeding may have helped their increase, and the decline of starlings in woodlands has allowed them a wider choice of nest holes. Now you can hear their loud drumming and distinctive chik calls over most of the British Isles. You can follow BBC Earth on,
or. Illustration by Mike Hughes Got holes in your tree? A myriad of insects, often beetles or clearwing moths, have a larval form that chew wood. Some feed deeply within the tree while others such as Emerald ash borer feed just below the bark. Once larvae become adults, they chew out of the tree. We usually see the exit holes and not the critter that caused it. Once we know the species of tree we can generally narrow the possibilities to the usual suspects. A major precursor to borer attack is a tree under stress. Stresses can come in the form of too little or too much water, compacted soils, covered trunk flare due to planting too deep, poor tree selection for site and other site or environmentally related issues.


Unfortunately multiple stresses can occur at the same time. Proper tree planting and maintenance is critical to reduce borer attack. If however the holes in your tree occur in straight lines, either horizontal or vertical, than the damage is probably from Yellow-bellied sapsuckers. They are migratory woodpeckers traveling long distances, as far as Panama for the winter and into the northern parts of Canada in the summer. This woodpecker attacks Illinois trees during both spring and fall migrations. They can damage trees as they migrate through in March, April and May and again in the fall in September and October. Sapsuckers rarely hang around our area in summer. Yellow-bellied sapsuckers are medium sized woodpeckers about the size of a starling with a jumbled mix of white and black feathers. Sapsuckers are the only woodpeckers to have a vertical white stripe on the side. Male sapsuckers have a red crown and throat. Sapsuckers can be found migrating through residential areas, parks and cemeteries this time of year. As their name implies sapsuckers feed on tree sap. They peck shallow, one-quarter inch diameter holes. They feed on the sap as it runs out of the holes. Sapsuckers have brush-like tongues that capture the sap of trees by capillary action. They also feed on insects that are attracted to the sap, but much of their diet consists of tree sap.


Pines, spruces, birch, sweet gums and fruit trees are most commonly attacked and individual trees can be attacked year after year. Rarely does the woodpecker kill a tree in this area, but extensive feeding can weaken the tree. Large amounts of sap may run out of the holes made in pine trees, congealing and turning white on the trunk. Although this looks alarming, it appears to have little or no effect on tree health. Because there is no apparent effect on tree health in Illinois and migratory birds need all the help they can get, a viable option is to do nothing. If you want to protect favored trees while the birds are flying through, wrap individual trees with tree wrap, burlap, hardware cloth or other protective material during migration to prevent further damage. Remove the wrap when the migration time has passed. Remember woodpeckers are classified as migratory nongame birds and are protected by the Federal Migratory Bird Treaty Act. This federal law and its associated international treaty make it unlawful to kill or otherwise harm woodpeckers and most other birds. Plus it would be a very uncool thing to do. Great resource for all things bird Cornell Lab of Ornithology Information on wildlife and how to live peaceably with furred and feathered creatures of the world

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