Cherries are a favored crop for many home growers, but the ripening fruit is highly appealing to birds like starlings, robins, and crows. Birds often target the fruit just as it begins to ripen, leading to significant crop loss. Protecting the cherries from this predation is necessary to ensure a successful yield.
Utilizing Physical Barriers (Netting and Cages)
The most reliable method for protecting cherries involves creating a physical separation between the fruit and the birds using netting. Bird netting, often made from durable, UV-stabilized materials like polypropylene, provides an effective barrier. Knotless designs are generally preferred because they are less likely to snag the tree or entangle birds.
Choosing the proper mesh size is important for effective exclusion. Sizes ranging from 0.62 to 0.7 inches (16 to 20 millimeters) are effective against common pest birds while still allowing for air and light penetration.
For smaller trees, the netting can be draped directly over the canopy, but ensure the net does not rest on the fruit, which would allow birds to peck through the mesh. For larger trees, creating a simple structure or cage around the tree is more effective. This framework, built from materials like PVC piping or metal stakes, keeps the netting fully suspended away from the branches and should be slightly taller than the tree for adequate clearance.
Sealing the barrier at the base is crucial once the net is draped over the tree or structure. Birds will readily access the fruit from below if the bottom edges are left open. The netting should be gathered tightly around the trunk and secured with twine, clips, or a bungee cord, or the edges can be anchored to the ground.
Employing Sensory Deterrents (Sight and Sound)
While physical netting offers the best protection, sensory deterrents are often used to supplement efforts or for trees too large to net practically. Visual deterrents rely on motion and light reflection to confuse and frighten approaching birds. Reflective flash tape, which is holographic and inexpensive, can be tied to branches to sparkle and flutter in the breeze.
Other shiny objects, such as old CDs, aluminum pie tins, or Mylar balloons, create a similar effect when hung near the ripening fruit. Predator decoys, shaped like owls or snakes, may also be placed within the tree canopy to suggest danger. However, birds are intelligent and quickly learn that stationary objects do not pose a real threat.
The effectiveness of these visual tools diminishes rapidly as birds become accustomed to them, a process known as habituation. To maintain effectiveness, these objects should be moved frequently, perhaps every few days, to a new location around the tree. Combining movement with the light generated by the reflective tape provides a more complex stimulus that is harder for the birds to ignore.
Auditory deterrents, such as electronic noisemakers or simple wind chimes, can also be employed to startle birds away. Some commercial devices utilize high-frequency ultrasonic sounds or broadcast bird distress calls, which can be effective initially. Continuous use of the same sound or frequency allows birds to adapt, suggesting that variable-frequency devices or a combination of different auditory methods may prolong their usefulness.
Adjusting Harvest Timing and Tree Management
Cultural practices and tree structure adjustments can reduce the period during which cherries are vulnerable to bird damage. Pruning the cherry tree to a manageable height and shape, such as a central leader or open vase system, makes the application of netting or other barriers much easier. This shaping involves removing upward-growing branches and maintaining an open canopy, which also improves air circulation and light penetration.
Keeping the tree height contained prevents the top canopy from becoming a target that is out of reach for protection efforts. Pruning sweet cherries to a central leader encourages an upright growth habit, while tart cherries often respond well to a modified central leader or open center structure. This proactive management allows for full coverage when the fruit begins to color.
A simple strategy to minimize loss is to harvest the cherries slightly earlier than peak ripeness if bird pressure is high. This approach removes the fruit before the window of maximum vulnerability, which occurs just as the cherries fully soften and turn their darkest color. Another concept is to plant less-favored fruit nearby, such as mulberries, which ripen around the same time as cherries and can act as a sacrificial crop to distract the birds.