How our proprietary bird repellent works

Bird Free is a pigeon repellent formulated to stimulate three senses of the bird: sight, smell and touch. These three stimuli combine to create avoidance learning in birds.


Bird Free’s proprietary gel mixture contains pyranine, the same colouring agent used in highlighters. This fluoresces when excited by UV radiation, causing the gel to glow with ultraviolet light. Invisible to humans, the UV light creates an impression on the bird similar to shimmering fire (hence the name Fire Gel™), causing it to avoid landing on surfaces treated with Bird Free. This avoidance reaction is observed immediately after Bird Free is applied.


Bird Free contains peppermint oil, long known as an effective bird repellent. Studies have shown that the menthol contained in peppermint derivatives acts as a primary repellent in birds due to its action on olfactory and trigeminal nerve endings located in the bird’s nose, mouth and eyes. (The trigeminal nerve is closely related to the olfactory nerve. It conveys facial sensations to the central nervous system.) The odour quality and pungency of the menthol is sensed by the olfactory and trigeminal systems of the bird, respectively, and creates a strong aversion response.

Synergy between visual and olfactory stimuli

In effect, these two stimuli, visual and olfactory, act together in synergy, warning the bird not to approach. As a result, birds quickly learn to keep away from surfaces treated with Bird Free repellent.

In the video showing the avoidance reaction, pigeons that used to sit on the chimney every morning learnt within a day of Bird Free being installed not to go near it. A video of the same chimney taken in October 2016, three years after Bird Free was applied, shows many pigeons flying over the chimney, but none land on it.


While the vast majority of birds are deterred by Bird Free's visual and olfactory stimuli and will not come into contact with the gel, where nests have been removed and treated with Bird Free a nesting bird will often be seen attempting to return to the nesting site immediately after Bird Free has been applied, causing it to touch the gel, which is very sticky. Due to the gel’s high viscosity the bird will not be harmed. However, birds abhor anything sticky on their feathers, so the bird only needs to touch the gel once and it will never return.  


Pigeon infestation above a junction box in a car park
Infestation site after cleaning and bird proofing has been carried out

Pigeons had been nesting on a junction box inside this underground car park for many years, resulting in damage to cars parked below. The nest was removed, and the surface of the box was disinfected. Dishes of Bird Free were then fixed where the nest had been at 15cm centres. Dishes were also fixed around the edge of the box at 25cm centres. The pest controller who carried out the treatment inspected the box three days later, and reported:

“There had been a pair of pigeons nesting against the wall for an extended period of time prior to clean-up and installation of Bird Free. After three days the top of the junction box was inspected. It was clear that there had been an attempt to reoccupy the habitat. There was a footprint in the Bird Free and a trail of gel was visible across the top of the box. There was evidently only a single attempt. Now there is no sign of pigeons in the vicinity of the junction box.” 

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Bird FreeOptical Gel and Fire Gel are registered trademarks of Bird Free Ltd.