The number of large birds in the rainforest has been declining for more than 40 years

The number of large birds in the rainforest has been declining for more than 40 years

In a 44 -year study, researchers at the University of Illinois found a decline in common bird species, including the Ocellated antbird (pictured), in a protected area in Panama’s Parque Nacional Soberanía. Researchers have not been able to pinpoint the exact causes of the decline, but it is called a causal factor. Found: John Whitelaw

In the depths of the Panamanian rainforest, the number of birds has been slowly declining for 44 years. A study conducted by the University of Illinois revealed that 70% of bird species were found in the forest between 1977 and 2020.

“Most of these kinds of things that you think would work well in a 22,000 -acre public park that haven’t seen a major land use change for the next 50 years,” Henry said. Pollock, postdoctoral researcher in the Department of Natural History and Natural Sciences. (NRES) in U of I and lead author in the study. “It’s very surprising.”

Jeff Brawn has to say that. Brawn is the Levenick Chair in Sustainability in NRES and a co -author on the research. He also studied birds at the Parque Nacional Soberanía, for the next 30 years.

“This is one of the longest, if not the longest, training of his kind in Neotropics,” Brawn said. “Of course, there’s only one park. We can’t expand the whole country and say the sky is falling, but it’s very close.”

The loss of birds from habitat could threaten the well -being of the entire ecosystem, Pollock said. In Neotropics, these birds are major pollinators, pollinators, and consumers. Small birds can threaten tree replanting, affecting the overall landscape of the forest, a trend that has been shown elsewhere since the decline of large birds.

But the researchers did not look at the consequences or the underlying causes. To begin with, Pollock, Brawn, and their colleagues focused on writing down the numbers.

In 1977, U school teacher Jim Karr, now professor emeritus at the University of Washington, began two years of bird testing. Each year, members of the team set up mist nets in the rain and dry season to catch birds that move around the research site. The fog nets gently attach to the birds, allowing the researchers to pull them out safely. Then they saw, measured, and tied the birds before releasing them safely to return to the forest.

Over 43 years and more than 84,000 modeling hours, researchers have captured more than 15,000 unique birds exhibiting nearly 150 species and collected relevant data to track 57 of the species. such things. The researchers found a decrease of 40 species, or 70%, and 35 species lost at least half of their original population. Only two species – a hummingbird and a puffbird – have been developed.

“When the study started in 1977, we captured 10 or 15 of the different species. Then by 2020, for most of the species, there will be fewer than five to six people. , “said Pollock.

Although birds exhibited different groups – specific groups with similar food sources – the researchers found a decline between three broad areas: common forest birds; ways to move during the season at higher altitudes; and special “border” features in transition areas between open and closed forest.

jungle forest

Available: CC0 Public Domain

According to Brawn, the decline in standards is alarming.

“Ultimately, these are birds that are doing well in that forest. And for whatever reason, they aren’t.

The decline of the two groups was not observed. Birds need to move to higher ground to survive, but the forest in Panama – like most other places – has increased in areas in recent years.

The margins were very complex, with most declines being 90% or more. Pollock and Brawn weren’t surprised, however. In fact, the loss of species has increased their confidence in their consequences. Because 40 years ago, a road that blocked the site was cut. He made a very good nest for birds that like the entrance of the forest. But over time, the road was no longer maintained and it became a small, forested road.

“Of course all sorts of things went awry when there was no way out,” Pollock said. “It shows what we can expect with the growth of the forest and the loss of those habitats.”

Researchers do not want to maximize their impact outside of their research field, pointing to the small number of similar simulations across the country.

“Right now, this is the only window we have into what’s working on the country’s bird populations,” Pollock said. “Our results raise the question of whether this is happening internationally, but we can’t answer that. But our study shows a lack of data. in the tropics and the importance of these long -term studies. “

The study is not designed to explain why birds are declining in the wild, but the researchers found some ideas they would like to follow. Factors such as changes in rainfall, food sources, and birth rates may all be related to climate change.

But for each reason, the researchers showed a quickness to think.

“Almost half of the world’s birds are in Neotropics, but we’re not well prepared for the trails of their populations. These populations,” Brawn said. “And we need to act fast.”

The article, “Long -term observation shows significant bird dropping below the protected Neotropical forest,” published in Proceedings of the National Academy of Sciences. Authors include Henry Pollock, Judith Toms, Corey Tarwater, Thomas Benson, James Karr, and Jeffrey Brawn.


The hummingbird shows when the growing trees are falling


More information:
Long -term observation shows that many birds are falling under the protected Neotropical forest, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073 / pnas.2108731119.

Presented by the University of Illinois at Urbana-Champaign

Directions: Decrease in bird population over 40 years (2022, April 4) retrieved 5 April 2022 from https://phys.org/news/2022-04-tropical-forest- major-bird-declines.html

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