\u201cWe\u2019ve known for several years that a lot of bird species in North America have been declining. With this study, we were aiming to understand in much finer spatial resolution where birds were declining and where they might be increasing. Rather than having a range-wide trend to see if a species is going up or down, we want to know where it is going up and down,\u201d said Alison Johnston, director of the Centre for Research into Ecological and Environmental Modelling at the University of St Andrews, UK, who led the study.<\/p>\n
\u201cThe main ecological finding is that the locations where these species were thriving in the past, where the environments were really well suited to birds, are now the places where they are suffering the most,\u201d she said.<\/p>\n
The researchers said further studies were needed to explain the reasons behind the changes, many of which were dramatic, with populations falling by more than 10% a year in some areas. Global heating and habitat change were put forward as the main theories behind the shifts, but Johnston said they ultimately did not know.<\/p>\n
\u201cThe way I interpret this result is that it\u2019s indicative of major changes in our world,\u201d she said. \u201cThe fact that where birds used to have strongholds, where there used to be a lot of resources, where the environments were really suitable, are now the places where they are declining most, that suggests to me that we are just seeing fundamental changes to the environments around us. The birds are like the canary in the coalmine,\u201d she said.<\/p>\n
The research adds to a recent series of studies that have documented severe declines of birds in nature reserves and protected areas.<\/p>\n
Despite the worrying overall picture, the researchers found pockets of stability in bird populations in their analysis, such as the Appalachians and western mountains. In addition, 97% of all bird species had some pockets where their populations were increasing.<\/p>\n
The team at Cornell University has previously developed methods for reliably converting citizen science observations in apps such as eBird into data that can be used to monitor population changes in a single species. The study authors only included results that had passed strict reliability checks.<\/p>\n
Prof Amanda Rodewald from the Cornell Lab of Ornithology, a co-author on the study, said the methods would allow conservationists to target their efforts.<\/p>\n
\u201cIt is this kind of small-scale information across broad geographies that has been lacking and it\u2019s exactly what we need to make smart conservation decisions,\u201d she said. \u201cThese data products give us a new lens to detect and diagnose population declines and to respond to them in a way that\u2019s strategic, precise and flexible. That\u2019s a gamechanger for conservation.\u201d<\/p>\n
Ian Burfield, a global science coordinator with BirdLife, who was not involved in the study, welcomed the research and said it highlighted areas for further investigation.<\/p>\n
\u201cNorth American birds are one of very few taxonomic groups and regions where such data exist to facilitate this approach. This emphasises the vital need for more field data collection, both through formal monitoring schemes and citizen science efforts, in many other parts of the world, especially in the biodiversity-rich tropics,\u201d he said.<\/p>\n