Out of the approximately 11,154 known bird species, 159 have become extinct, 226 are critically endangered, 461 are endangered, 800 are vulnerable and 1018 are near threatened. There is a general consensus among scientists who study these trends that if human impact on the environment continues as it has one-third of all bird species and an even greater proportion of bird populations will be gone by the end of this century. Since 1500, 150 species of birds have become extinct. Historically, the majority of bird extinctions have occurred on islands, particularly those in the Pacific. These include countries such as New Zealand, Australia, Fiji, and Papua New Guinea. Some species are not extinct and seem numerous, but exist in highly reduced numbers from previous years. For example, the Wood Thrush population in North America has declined 50% in the last 50 years. According to the American Bird Conservatory, in the Western Hemisphere 12% of bird species are declining at a rate such that they will be extinct within the next century.
As climate change is caused by a variety of activities, the effect that climate change has on bird extinction is immense. Due to the rapid changes in temperature and climate the bio diverse earth can not progress with these factors. Severe weather conditions and long seasons, as well as a chemical atmosphere within their surroundings, makes it difficult for many species of birds to keep up with. In Hawai'i, climate change is responsible for the decline in the population in Hawaiian forest birds and is resulting in an increase of avian malaria. Because the dynamics of malaria are influenced by ambient temperature and participation patterns, the predicted climate changes are expected to increase the occurrence of avian malaria. Sea level rise may flood islands killing the birds and other animals native to islands causing extinction.
Disease
Each species of birds carries defense mechanisms like resistances and the ability to fight disease. With the changing climate and atmosphere, many species are losing their ability to fight particular diseases. These bird species are becoming more susceptible to disease, which results to the downfall of extinction. The most common disease affecting birds is Salmonellosis, which originates from the Latin name of salmonella. Infected birds pass bacteria in their fecal droppings, and other birds then become ill when they eat food contaminated by the droppings.
