In some cases Pigeons and Seagulls can be a problem if they gather in large numbers on roofs and buildings, leaving a lot of bird poop or creating noise and unwanted disturbances. Natural scavengers, pigeons often carry disease and are a general nuisance to people on the street, leaving bird poop and other germ-ridden deposits wherever they go. While many pigeons like to travel along the ground, they make their homes on the rooftops and in the eaves of nearby buildings and leave piles of pigeon poop that can add up and become hardened overtime and almost impossible to clean, especially since they are in hard to reach places. A pigeon problem is one that can be avoided and possibly eliminated through the use of pigeon repellent.
One way to prevent pigeons from making nests and landing on roof tops, eaves, balconies and other high places is to deter them with pigeon repellent spikes. Pigeon repellent spikes are strips of metal or plastic spikes that are sharp and when used along places that pigeons like to perch, can prevent them from landing comfortably.
As well as spikes there are special gels designed to keep birds away from roof tops and walls. These gels are sticky to the touch and have a texture that pigeons and other birds will avoid. Consider gels if you find the spikes unsightly for your situation. Sticky solutions may work best as a pigeon repellent as they can be used both indoors and outdoors. This type of repellent makes a landing surface uncomfortable for pigeons and will force them to look elsewhere for a place to roost.
Another more flexible of bird repellent is to use an ultrasonic repeller. Ultrasonic repeller emit a signal on a frequency that pigeons and other birds cannot tolerate - but is inaudible to us humans. Normally the ultrasound is only used when triggered by a passive infra-red detector.
A scarecrow may trick pigeons for a time, however most pigeons are not as afraid of humans as other birds and this may not work at all. Outlines of hawks or other bird predators are more likely to scare birds away.