No smell has research behind it. The lists of pigeon repellent smells you meet online run long. Peppermint oil, chili powder, cinnamon, vinegar. Nothing in the retrieved research tests them on pigeons. So the honest answer is that scent is the wrong tool, not that you picked the wrong scent. What the research does back is physical and dull, and it comes down to one move. Close the openings the birds are using.
A smell asks a pigeon to give up a ledge it already likes, and the bird gets a vote. It can shift six feet down the same sill and carry on. A blocked vent takes the vote away, because there is nothing left to stand on or nest in. Only one of those two approaches shows up in the extension research with real detail behind it.
Habituation is the reason scent bird repellents keep letting people down. Minnesota Extension records that some birds adapt to methods that alarmed them at first, so the deterrent fades out while the roost stays put. No time frame comes with that finding. You cannot plan around a clock nobody has measured, and no retrieved study tests a smell, a sound or a taste on pigeons in the first place.
A homemade pigeon repellent does have one real advantage, and it is not that it works. Sensory deterrents take less installation labor than netting. That is the single documented point in their favor. An hour with a spray bottle beats an afternoon on a ladder with netting, clips and a drill in one hand. But the cheap job is the one you keep redoing, and the birds sit through every round of it.
Cost is the other reason pigeon repellent smells get tried first. They are the cheapest thing on the shelf and the fastest thing to try, and there is nothing wrong with trying one. Just treat it as a stopgap. Nothing in the research says a scent moves a bird off a roost it has already picked, so the ledge you sprayed on Sunday can hold the same pair on Monday. If sealing the vent has to wait a week, spray in the meantime. The vent is still the job.
Spikes and porcupine wire have a related flaw. They do not work on smaller birds, which slip between the points and nest there anyway. The numbers on the box help even less. Warranty terms and break strengths come from the seller, and nobody outside the company checks them, so read those figures as marketing copy.
That leaves the physical work, which is the part that holds. To stop pigeons returning, close the way in. Lofts, steeples, vents and eaves get blocked with wood, metal, glass, masonry, 1/4 inch (6 mm) rustproofed wire mesh or plastic netting. Match the material to the opening and fasten every edge down. The full exclusion sequence runs longer than this answer, so work from that rather than from this paragraph alone.
Old nesting material carries nest mites and lice. Put gloves on before you clear a ledge, a vent or a loft, and keep them on for the whole job.
One thing works in your favor here. Pigeons, house sparrows and European starlings are the birds not protected by state or federal law. The rest are. So if the birds are pigeons, sparrows or starlings, you can seal your own building without a permit question hanging over the work. Spend that room on mesh, screws and a ladder. The scent aisle has nothing behind it, and the ledge is still occupied in the morning.
Read the full article: Bird Netting That Works Without Trapping
