David McNew/Getty Images(CNN) - 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.
But for the first time, the results also showed pervasive losses among common birds across all habitats, including backyard birds."
Almost 90% of the birds lost came from 12 common songbird families like sparrow, blackbirds, warblers, finches and swallows.
Shorebirds have also lost one-third of their population, and grassland birds lost more than 720 million, resulting in a 53% population reduction.
The loss of grassland birds in North America is similar to a decline in farmland birds across Europe, according to the study.