Science: North American birds have declined by more than a quarter in the past 50 years

, Sept. 21 (Xinhua) -- From the iconic songbird meadows , to the long-distance migration of swallows, to the sparrows living in the backyard... Bird populations between the North American continents are declining at an alarming rate. A study published online in the new issue of the American journal Science says bird populations in the United States and Canada have declined by 29 percent since 1970, with about 2.9 billion birds disappearing from the North American continent.
In a 10-year study, researchers from Cornell Ornithology Laboratory, the American Bird Protection Association and others collected data on bird migration monitoring at 143 radar stations across the United States under the U.S. Next Generation Weather Radar Program and analyzed data from several ground monitoring programs over the past 50 years.
90 percent of the approximately 2.9 billion birds that have disappeared from the North American continent in the past 50 years are concentrated in 12 branches, including oats, finches, and pythons, many of which are important for sowing seeds, pest control and other ecosystem functions. In terms of habitat, the number of prairie birds fell by 53 per cent to more than 720 million, while the number of coastal birds living in coastal habitats fell by more than a third. In addition, the number of birds migrating in the spring fell by about 14 per cent.
birds are a pointer to environmental health. The new study shows that the natural systems of the United States and Canada are so severely affected by human activity that they cannot support wildlife populations as robust as they used to be.
Mara, director of the Georgetown Environmental Initiative at Georgetown University in the U.S., who was involved in the study, said the findings are consistent with those of other animal populations. Previous studies have found a significant decline in the number of insects, amphibians, etc.
researchers believe that changes in bird populations in North America can reflect trends in bird populations in other parts of the world, with a variety of interacting factors reducing bird reproduction rates and increasing their mortality rates. The most likely cause of the sudden decline of birds is the loss and degradation of their habitat, which is mainly the result of human activities such as urbanization and agricultural intensiveization.