via.q13fox.com
US and Canada have lost 2.9 billion birds since 1970, study says
Bird populations in the United States and Canada have dropped by 29% since 1970, signifying 2.9 billion birds lost in almost 50 years, according to a new study. The scientists involved in the study warn that like a canary in a coalmine, birds reveal environmental health. This steep loss of bird populations, including some of the most common birds like sparrows and finches, shows that human impacts on the continent's environment mean it can no longer support the wildlife systems it once did.