Vertical lines of woodpecker holes

It is not unusual to see a vertical line of woodpecker holes on a tree. This is often the result of a pair of woodpeckers having created new nesting cavities in a favourite tree year after year. A favourite tree is one that has proved easy to excavate and which was successful for breeding. Sometimes such lines of holes are due to the birds having started a cavity and then abandoned it before moving on to another spot on the same tree trunk. It can also be the case that some of the holes in a line lead to the same, single cavity. That is, the cavity within the tree trunk has more than one entrance. But in this case, it is not clear whether this is by accident or by design. Woodpeckers also produce lines of holes when searching for tree dwelling prey. This example of a series of Black Woodpecker holes in a beech tree was taken by Szabolcs Kokay in the Zemplen Hills, Hungary.