Great question, and yes—you can keep birds from nesting under a street bench without harming them. I’ve dealt with this around a park bench, and the best results come from making the space unusable, not from scaring or hurting the birds.
First, check for an active nest. If there are eggs or chicks, leave it alone until the young have fledged. In many places, disturbing an active native bird nest is illegal. Once the bench is empty, act quickly, ideally before nesting season gets going.
The most effective humane bird deterrent is a physical barrier. Attach galvanized hardware cloth or bird netting tightly across the underside of the bench. Use a small mesh—about 1/2 inch or smaller—so birds cannot push through. Pull it taut and fasten it to the bench frame with staples or zip ties, trimming edges so there are no gaps. Birds need a stable ledge or cavity, and the barrier removes it.
If the bench has a flat, open underside, install a sloped panel instead. A piece of wood, plastic, or corrugated sheet fixed at a 45-degree angle will make nesting impossible because birds cannot build on a smooth slope. This is a quiet, low-maintenance solution.
Also seal small gaps where the seat meets the frame or armrests. Pigeons, sparrows, and starlings often wedge nests into those joints. Use hardware cloth or stainless steel scouring pads to block them, but avoid loose fibers that birds could pull out and use as nesting material.
You can add a mild visual deterrent, but don’t rely on it alone. Reflective tape or a small hanging pinwheel may startle birds for a few days, yet many birds get used to them quickly. Use visual aids only alongside a physical barrier.
For a safe scent option, try a non-toxic peppermint or citrus spray. Mix a few drops of pure peppermint oil with water and a tiny amount of mild soap, then spray the underside of the bench. Reapply after rain. Avoid sticky gels or glue traps, which can injure birds and other wildlife.
Keep the area clean. Remove loose twigs, grass, or feathers before they become a full nest. And if you want to give birds a better option, place a simple nest box or encourage dense shrubs a short distance away. That way they can settle safely without using your bench.
One quick note: if the bench is public property, check with the local council or parks department before attaching anything. Many will allow temporary zip-tie barriers or can install something themselves.
With a tight wire barrier or a sloped panel, you’ll solve most of the problem in one afternoon, and the birds will simply choose somewhere else.