One of the most annoying pests are pigeons because of the great damage they can cause with their droppings.
Pigeons are important vectors for different species of the bacteria Salmonella which causes diseases as Salmonellosis and Paratyphoid fever.
The bacteria Chlamydophila psittaci is endemic among pigeons and causes Psittacosis in humans. It is transmitted both from handling pigeons but mostly from their droppings. Psittacosis is a serious disease but rarely fatal (less than 1%).
There is ample reason for the concerns of pigeons damaging property, due to their size and proximity to people and their dwellings. Pigeons often cause significant pollution with their droppings. Pigeons are labeled an invasive species in North America by the USDA.