The bird population in the US and Canada has fallen by almost three billion since 1970, according to scientists.

Published in the journal Science, the study was carried out by scientists and conservationists from multiple institutions and looked at nearly five decades of population data on 529 species of North American birds. The study shows that populations have declined by an estimated 2.9 billion individuals or 29%.

Ornithologist and lead author Ken Rosenberg, from the Cornell Lab of Ornithology and American Bird Conservancy, admitted that scientists knew some bird populations were on the decline but the sheer number of losses were ‘stunning’.

Speaking to IFLScience, he said:

We thought that increases in other species would balance everything out overall. That’s not the case at all.

The research found the amount of birds present at the start of the breeding season has fallen from just over 10 billion to little more than seven billion in the last 50 years, meaning the US and Canada have lost more than one in four birds.

Grassland species like Western Meadowlarks and American Sparrows have been hit the hardest with more than 715 million birds disappearing since 1970. Shorebirds such as green herons have had one-third of their population numbers wiped.

3 Billion Birds Have Vanished From North America In The Last 50 Years
Cornell Lab Of Ornithology

According to the Cornell Chronicle, Rosenberg commented on what the results may mean, saying:

It’s a strong signal that our human-altered landscapes are losing their ability to support birdlife. And that is an indicator of a coming collapse of the overall environment.

The bulk of the losses haven’t been rare species, but rather common birds. A dozen bird families, including finches, warblers and blackbirds, accounted for 90 per cent of the total loss, according to IFLScience.

3 Billion Birds Have Vanished From North America In The Last 50 Years

Pete Marra, an ecologist who worked on the study, spoke to NBC News about the findings.

He explained:

We can all talk through the stories about there being fewer and fewer birds, but it’s not until you really put the numbers on it that you can really grasp the magnitude of these results.

We’re now seeing common species that have declined, things like red-winged blackbirds and grackles and meadowlarks — species that I grew up with, that were very common when I was a kid. That is the most surprising and most disturbing part.

It’s an empty feeling in your stomach that these same birds that you grew up with just aren’t there anymore.

President of the American Bird Conservancy and a co-author of the study, Mike Parr, described the findings as an ‘indication that nature is unravelling and that ecosystems are highly stressed’.

Researchers say humans are the driving force behind the decline through the clearing of land, widespread pesticide use and by allowing domestic cats to roam outdoors.

3 Billion Birds Have Vanished From North America In The Last 50 Years
Cornell Lab Of Ornithology

Along with the negative data, there was some positive findings; Waterfowl numbers have grown over the last 50 years thanks to policies such as the 1972 Clean Water Act which have helped conserve wetlands. Bald eagles also thrived after DDT pesticides were banned and legislation was passed to help protect them.

Dr. Rosenberg says he is ‘hopeful’ that bird populations will bounce back but there needs to be changes made in order for them to do so.

The researchers agreed lawmakers could help by enacting legislation to conserve federal lands and stop the use of neonicotinoid insecticides, while members of the public can help by keeping pet cats indoors and eating organic food to help reduce the use of pesticides.