Many bird species make their habitat alongside humans from rural to urban environments. They can become pests since they have adapted to survive off of human byproducts and find opportunity in human actions and creations. Pigeons are the most common of these pests to be found in populated areas. Although sparrows and European starlings are also found where humans live. Feral birds will eat a broad range of foods they find from humans, and rifle through receptacles to find sustenance.
Birds can cause significant damage to structures that can be quite costly to repair. They also have the potential to contaminate many products. And birds will steal a variety of livestock feeds. Some even transmit and carry deadly diseases such as rabies. Pets can contract these diseases from proximity to their dead bodies.
Signs of tier presence can be seen by finding their droppings, feathers, and nests. Their chirping can also be heard, and in most cases you will be able to see the birds themselves quite often around your home or business. Birds can be removed or prevented from making their homes in your buildings, which can save you the money of having to fix structures once they have established themselves within.