Environment

Study states almost 3 billion North American birds have vanished since 1970

Study states almost 3 billion ...
Sparrows are still quite common, but the study suggests that their numbers have dropped drastically over the past few decades
Sparrows are still quite common, but the study suggests that their numbers have dropped drastically over the past few decades
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Sparrows are still quite common, but the study suggests that their numbers have dropped drastically over the past few decades
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Sparrows are still quite common, but the study suggests that their numbers have dropped drastically over the past few decades

Even though a species may be considered "abundant," there's definitely still cause for concern if it's becoming significantly less so. A new study indicates that this is the case with North American birds, the total number of which has reportedly declined by 29 percent since 1970.

Led by Cornell University conservation scientist Kenneth V. Rosenberg, a group of American and Canadian researchers recently examined multiple datasets from ground-based bird-monitoring stations, going back 48 years. They determined that for 529 of the most common species in both countries, a net loss of 2.9 billion birds has occurred since that time.

Over 90 percent of the loss took place within 12 bird families, which included songbird species such as warblers and sparrows. On the other hand, species such as waterfowl and raptors have actually experienced a population increase. This is likely due to conservation efforts, which the study suggests should be extended to other bird species that aren't doing so well.

Additionally, the team analyzed data from the continent-wide NEXRAD radar network, which is capable of detecting flocks of migratory birds. Based on this, it was determined that the "biomass passage of migrating birds" has undergone a similarly steep decline in the past 10 years, particularly in the eastern US.

"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," the researchers state. "Given the current pace of global environmental change, quantifying change in species abundances is essential."

A paper on the study was recently published in the journal Science.

Source: American Association for the Advancement of Science via EurekAlert

6 comments
Tony Morris
A 29% decline in total bird population over 48 years - not surprising - our planet has lost 50% of its wildlife over a similar period. It has been reported that here in Australia we lose 1 million birds per day due to feral introduced cats alone.
True Ad Venture
Feral introduced humans have also taken a huge toll on Aussie wildlife.
BrianK56
Insects are their primary food source. Insecticides have been increasing in use and potency for the past 50 years. Eating enough poisoned insects could have caused this.
Cryptonoetic
Hundreds of millions of birds are killed annually by wind mills.
Robert in Vancouver
Really big killers of birds - windmills. Windmill operators go early each morning to pick up all the dead birds before people can see the carnage. To make matters worse, windmill energy costs a lot more than energy from dams, nuclear, or natural gas.
DaveWesely
@BrianK56 In addition to insecticide use is the common use of the BT gene in GMOs. I would imagine that entire fields of poisonous plants for insects would have a huge effect on insect populations, not just the pests. I live in the North American Great Plains. Hardly see any grasshoppers any more. They were everywhere in the 70's.