Predation: Bluebirds are preyed upon by a variety of animals, including snakes, cats, and hawks. Nestlings and eggs are particularly vulnerable to predation.
Habitat loss: The loss of natural habitats, such as open fields and woodlands, has reduced the number of suitable nesting sites for bluebirds.
Pesticides: Bluebirds can be poisoned by pesticides used in agriculture and on lawns.
Climate change: Climate change is causing the weather to become more unpredictable, which can make it difficult for bluebirds to find food and nesting sites.
Disease: Bluebirds are susceptible to a variety of diseases, including avian pox, West Nile virus, and salmonellosis.