news sign: Don't miss out on the latest news Sign up for our daily briefing Multiple, independent lines of evidence show a massive reduction in the abundance of birds, said Ken Rosenberg, the study's lead author and a senior scientist at the Cornell Lab of Ornithology and American Bird Conservancy, according to National Observer. Co-author Adam Smith from Environment and Climate Change Canada called the findings a wake-up call . The population losses are consistent with what scientists have counted among insects and amphibians. ; The study, published today in the journal Science, did not analyze the reason for the drop. The US and Canada have lost more than one in four birds a total of three billion since 1970, culminating in what scientists who published a new study are calling a widespread ecological crisis . Researchers observed a 29% decline in bird populations across diverse groups and habitats from songbirds such as meadowlarks to long-distance migratory birds such as swallows and backyard birds like sparrows. But around the world, birds are thought to be dying more and having less success breeding largely because their habitats are being damaged and destroyed by agriculture and urbanization. Sources include citizen science from the United States Geological Survey, the Canadian Wildlife Service, the Audubon Christmas Bird Count and Manomet's International Shorebird Survey. Researchers calculated the declines with 10 years of information on migratory birds from weather radar stations and 50 years of data from the ground. (www.immigrantscanada.com). As reported in the news.