Large flocks of black birds, including European starlings, common grackles, and crows, cause several problems for property owners. Issues range from property damage due to corrosive droppings and the risk of disease transmission from accumulated feces, to disruptive noise from communal roosts. Their feeding habits can also devastate crops and garden seeds. Effective deterrence requires a multi-step approach: modifying the environment, blocking access with physical barriers, and employing sensory techniques to encourage relocation.
Removing Environmental Attractants
The foundational step in managing bird presence is eliminating the resources that draw them to an area. Bird feeders are a primary attractant; temporary removal for two to three weeks encourages flocks to find new feeding grounds. If feeders are used, switch the seed type, as blackbirds prefer cracked corn, millet, and general seed mixes. Offering straight safflower or Nyjer seed is a selective strategy, since safflower shells are difficult for larger blackbirds to crack, and Nyjer seed appeals mostly to smaller finches.
Sanitation practices also play a role in resource denial, especially in urban settings. Secure trash cans with tight-fitting lids to prevent access to discarded food. Fallen fruit or spilled seed beneath feeders should be cleaned up daily to eliminate easy ground-level foraging. Reducing standing water sources, such as overflowing bird baths or clogged gutters, removes accessible drinking and bathing spots, making the habitat less appealing for long-term roosting.
Passive Exclusion Methods
Passive exclusion involves installing fixed, physical barriers that prevent birds from landing or entering a specific location without inflicting harm. Bird netting is a versatile method, creating an impassable barrier over large areas like fruit trees, gardens, or beneath eaves. Netting should be properly tensioned to prevent sagging, which can entangle birds and reduce effectiveness.
For narrow surfaces where birds attempt to perch, such as window ledges or beams, bird spikes are an effective solution. These devices use blunt-tipped stainless steel or polycarbonate pins that create an unstable surface, preventing birds from landing without causing injury. Alternatively, tensioned wire systems can be installed along ledges using fine wires held taut by small posts, creating a subtle, unstable landing spot that birds avoid.
For areas like chimneys or vents, specialized caps and wire mesh screens block nesting access points. On wide ledges, installing a covering material at a steep angle, such as 60 degrees, eliminates the flat surface needed for roosting.
Active Deterrence Techniques
Active deterrence relies on sensory input, specifically visual or auditory stimuli, to frighten birds away. Visual deterrents utilize the birds’ natural aversion to unexpected movement and bright, shifting lights. Items like holographic flash tape or reflective Mylar balloons create unpredictable flashes of light and movement that birds find disorienting.
Shiny objects such as old compact discs or reflective spinners can be hung near roosting sites to act as visual alarms. Predator decoys, which mimic threats like owls or hawks, can also be used. However, decoys must be moved frequently to prevent the birds from becoming accustomed to the static threat.
Auditory methods use noise to signal danger. Species-specific distress calls are the most effective tool, as these recordings mimic alarm cries, signaling that the area is unsafe and prompting an immediate flight response. General noise-makers like propane cannons are less effective long-term because birds quickly acclimate to repetitive sounds. Ultrasonic devices are sometimes marketed as deterrents, but studies report limited effectiveness against common pest species.