Bird populations in the United States and Canada have dropped by almost 30% since 1970, signifying almost 3 billion birds lost in almost 50 years, according to a new study.

WASHINGTON, September 20 (WNM) -"Citizen-science participants contributed critical scientific data to show the international scale of losses of birds," said John Sauer, study co-author at the US Geological Survey. "Our results also provide insights into actions we can take to reverse the declines." The study was published Thursday in the journal Science. Species extinctions have defined the global biodiversity crisis, but extinction begins with loss in abundance of individuals that can result in compositional and functional changes of ecosystems.

Using multiple and independent monitoring networks, the study reports population losses across much of the North American avifauna over 48 years, including once common species and from most biomes.

Integration of range-wide population trajectories and size estimates indicates a net loss approaching 3 billion birds, or 29% of 1970 abundance.

A continent-wide weather radar network also reveals a similarly steep decline in biomass passage of migrating birds over a recent 10-year period.

This loss of bird abundance signals an urgent need to address threats to avert future avifaunal collapse and associated loss of ecosystem integrity, function and services. The study is published here: https://science.sciencemag.org/content/early/2019/09/18/science.aaw1313