Sugar Maples Make a Great Snack for Sapsuckers

 

Holes in rows caused by sapsuckers

What are the small holes that are spaced in horizontal rows across the bark in some trees? Sometimes there is a dark coloration of the bark below. What is causing this, and could it harm the trees? The holes are the result of the activity of sapsuckers, a species of woodpeckers feed on the tree’s sap.

     Sapsuckers are migratory birds that are most prevalent during the spring and fall. They prefer maple trees, but will also feed on pecans, Bradford pears, and several others. The birds choose these trees due to the high sugar content of their sap. It composes up to 20% of their diet and is especially crucial during the year when other food sources are in short supply. The birds also eat insects they find on the trees. They peck a small hole, roughly one-eighth to one-quarter of an inch in diameter and a depth of one-quarter of an inch in the tree's trunk. They will then use their tongue to suck up the sap. The holes are evenly spaced up, down, and around the trunk and appear as if a machine drilled them. Often the sap will flow down the trunk of the tree. It promotes the growth of black sooty mold. Sometimes these holes are mistaken for insects that bore into the tree trunks. However, the ones caused by insect borers are more randomly scattered throughout the tree.   

     The feeding activity of sapsuckers rarely causes harm to the trees. The holes they make are quite shallow. Many times trees can have hundreds of holes bored into their bark and not suffer at all. In rare cases, if the tree has been weakened due to other factors, such as drought or previous pest activity, there is a remote chance the sapsucker activity could harm the tree.

     The sapsuckers are not easily deterred, so begin the necessary control measures as soon as damage is observed. Use a burlap or hardware cloth to cover the trunk around the area being attacked by the sapsuckers. It will keep them away from the trunk.

Hanging reflective objects in the trees, like aluminum foil or shiny pinwheels, will also discourage the birds since they dislike bright or flashy objects. Leave these devices in place for a few weeks after you have noticed the activity has ceased to make sure the birds do not return. Repetitive loud noises, like a barking dog, can also scare them away. Another method of control is smearing a sticky bird repellent onto the tree trunk. There are several types of these products that are available at most garden centers. Although this material will not hurt the birds, it will cause a tacky feel to the tree's surface, creating discomfort to the birds, thus driving them away. One crucial factor to remember is sapsuckers are classified as migratory, nongame birds. The Federal Migratory Bird Treaty Act protects them. Killing them by shooting, using toxicants, or any other lethal method is illegal.    

   Sapsuckers are one of nature’s more exciting wonders. Usually, they are best left alone since they seldom pose a threat to the trees they feed.