National Geographic wrote about the continuing decline of North American Bird Populations. They are talking about all birds; many common birds as well as rare birds. Although Global Warming, Wind Turbines and Cats are significant threats to birds, the number one negative impact on bird populations is habitat loss. A recent Audubon report found that some widespread species had suffered 80 percent population declines and 19 other species had population losses of 50 per cent.
Read more at National Geographic North American Birds Declining as Threats Mount.