The serious and constant public health problems feral pigeons create are unmatched by any other bird species. Pigeons are known to carry or transmit several diseases and their droppings and feathers can contaminate food destined for human consumption. Their droppings deface and accelerate the deterioration of homes and buildings and also contaminate areas where people walk or work. Pigeon droppings and nests clog gutter downspouts and air intakes, mar window sills, and render fireplaces and fire escapes hazardous. Pigeon ectoparasites include chewing lice, ticks, and mites, some of which bite people, which is why pigeon control should always be a priority.