Bird nests come in many shapes and sizes. Each species has a unique method used to choose suitable locations and construct nests to house their young. Many birds build their nests among tree branches or shrubs, while others prefer tree cavities, on the ground, in the crevices of manmade buildings, or under bridges. Some species do not build nests at all and instead lay their eggs in the nests of other birds. Those that do build nests generally construct a shell of sturdy materials like sticks, plant stems, and grasses held together with mud. The interior is lined with soft materials like moss, animal fur, dried leaves, string, or bits of cloth. Health Risks Nests located too close to human homes cause health and safety hazards. Accumulations of bird droppings below nesting sites cause a fungus known as histoplasmosis to grow, which leads to dangerous respiratory problems for humans. Their droppings can also contaminate food or water sources with diseases such as salmonellosis, Newcastle disease, and psittacosis, each of which incite severe health problems. Furthermore, the nests themselves often harbor pests like ticks and mites. Additionally, bird nests are typically made of highly flammable materials, such as dried plant matter, and are serious fire hazards, especially when they are located near power lines. Bird Nest Removal Although it can be tempting to knock down an unwanted bird nest with a broom or blast of water from a hose, the Migratory Bird Treaty Act of 1918 protects most birds, their eggs, and their nests from being killed or destroyed. Disturbing bird nests may be considered a federal crime carrying steep fines and possible prison sentences. Depending on the species, special permits from state wildlife agencies must be obtained before bird nests can be removed. Instead of risking retribution, individuals should contact the wildlife removal experts at Critter Control to handle the matter of unwanted bird nests in a legal and humane way.