Your trees are suffering from damage imposed by a sapsucker (woodpecker). The sapsucker will peck holes in the bark, usually in a recognizable pattern, causing the tree to bleed sap. The bird may ingest some of the sugary sap for carbohydrates, but will return later to eat any insects that were attracted to the sap. Although unsightly, sapsucker damage is rarely lethal. If otherwise healthy, the tree will simply grow around the wounds.