Climate Change is Transforming the Bodies of Amazon Birds

Alex Fox of Smithsonian writes about the evolution of Amazon birds in response to climate change:

Bird golden crownA 40-year study found 77 species of rainforest birds weigh less on average, and many have longer wings, than they used to. Here is a short excerpt:

When the first ever World Climate Conference concluded in February 1979, the scientists in attendance issued a statement calling on world leaders "to foresee and prevent potential man-made changes in climate that might be adverse to the well-being of humanity." On October 17 of that same year, scientists deep in the Brazilian Amazon unfurled a set of 16 mist nets at 6 a.m. to begin a study of the birds living in the understory beneath the rainforest’s green roof.

In the 40 years that followed, climate change went from a far-off-seeming idea to a grave reality that grips every square inch of the planet, and hundreds of dedicated researchers kept opening the mist nets at dawn to capture and study the feathered inhabitants of an intact patch of Brazilian rainforest about 40 miles north of Manaus.

Now, a new paper leveraging this long-running study, originally aimed at testing the impacts of forest fragmentation, shows that as human activities have altered Earth’s climate, the bodies of birds living in the understory of this remote, undamaged patch of rainforest have been changing in response. The authors of the paper report today in the journal Science Advances that all 77 species of birds surveyed by the study weigh less on average than they did 40 years ago and nearly 80 percent of those species also have developed greater average wing-lengths.

Researchers aren’t yet sure what the consequences of these physiological changes might be or the precise mechanisms that gave rise to them, but the team’s analyses suggest the rising temperatures and changes in rainfall seen at the study site offer the most powerful statistical explanation for the birds’ transformation.

“This is the middle of the Amazon rainforest, far away from deforestation,” says Vitek Jirinec, an ecologist at Louisiana State University and the paper’s lead author. “But even here, in this place that is teeming with life and looks totally undamaged, you can’t escape the consequences of climate change.”

Jirinec and his co-authors embarked on this study in earnest in 2020 after finding that 21 species of birds at this site north of Manaus, known to researchers as the Biological Dynamics of Forest Fragments Project (BDFFP), were in decline. Even within this protected area, buffered from logging and pollution, some species had declined by as much as 40 percent, especially insect-eaters. Those results, published in 2020, led Jirinec and his colleagues to try to tease out what might be going on, and, in particular, to probe the role of climate change.

To do that, the researchers compiled the weights of 14,842 individual birds and the wing lengths of 11,582 birds recorded by BDFFP scientists between 1979 and 2019 and paired those data with the last 50 years of changes in temperature and precipitation in the region. 

In terms of climate change, the team found that compared to 1966 this region’s wet seasons have become 13 percent wetter and its dry seasons are now 15 percent drier. The average temperature for both seasons has also increased over that time span, with temperatures rising by 1.8 degrees Fahrenheit in the wet season and 2.97 degrees in the dry season.

Among the birds, all 77 species in the study showed average decreases in body weight over the last four decades, with some species losing nearly 2 percent of their mass every decade, and 61 species showed increases in average wing-length. Statistical analysis linked those changes to climatic shifts.

The results fall short of demonstrating cause and effect, but show a strong association. “The relationship between body size and climate change is correlational, naturally,” writes Mario Cohn-Haft, an ornithologist with Brazil’s National Institute of Amazonian Research who wasn’t involved in the paper, in an email. “But both several-decade long trends and year to year trends are demonstrated here with a monstrous amount of data to support them.”

The study found that birds tended to be lighter following hotter and drier conditions than usual, especially if those conditions fell during the dry season, which is the most stressful time of year for birds because food is harder to find.


In Support of Pigeons







Atlas Obscura writes a compelling article on pigeon watching and the history of that bird. Here is a short excerpt from an interview with bird-watching mom, Rosemary Mosco :

What’s so awesome about pigeons?

What makes our city pigeons really cool is that they are feral domesticated animals. They’re basically like a stray cat or like a feral dog: mutts mixed from a whole bunch of different, really amazing breeds. To understand where they came from, you have to understand purebred pigeons.

Pigeons were domesticated over 5,000 years ago. We have some rough information, but it’s really hard to untangle that early stuff because we’re bumping up against the dawn of recorded writing. We know it happened in the Fertile Crescent, and that it coincided with people farming grain—because if there’s one thing that pigeons adore, it’s grain.

Domestication is a complicated process. It probably didn’t happen in one place or at one time—it probably happened a few different times. People started farming, the pigeons started to hang around the people, and people realized these pigeons could be useful. They built structures that encouraged the pigeons to nest, threw down some grain, and then it slowly took off from there.

Where’s the best place to camp out and see pigeons?

They just love anywhere urban. Anywhere there are people in large numbers and the food that people consume, they will be there. They’ll also be in agricultural areas or little towns, but you’ll definitely see most of them in the city, because you’ll see the most people and the most people dropping food. They’re really just all over the place, and they’re there all year round, so you don’t have to travel to go see them.

The only place that is really not great for pigeon-watching is anywhere that’s really, really wooded. They really don’t do well when they’re far away from people now because we’ve molded them for so many years. This is what they’re suited for. You won’t see them in a redwood tree.

Pigeons often forage near trash cans. What are they looking for?

They’re not super discerning, but they have their preferences; they won’t just eat whatever is in the trash. They really prefer legumes—lentils, peas, that kind of stuff. A lot of the food that people trash is bits of bread or crackers. That’s what they like. The other day I walked past a flock of pigeons and someone had dropped a bunch of lentils. And I was like, “Wow, someone really knows their pigeon ecology.”

How has pigeon-watching affected the way you experience the rest of the world, whether natural landscapes or the built environment?

Because pigeons are so prominent in the city, if you watch them, you will tap into so much more that’s happening in the urban bird world. In my area, they’re the main prey of birds like the peregrine falcon, and red-tailed hawks and Cooper’s hawks also eat them. Noticing them helps you tap into the whole world of urban bird-watching.

Also, it is really interesting to look at the city and realize how similar it is to a stony cliff–like environment. People often ask, “Where are the baby pigeons? How come you never see baby pigeons?” It’s true you rarely see baby pigeons, or by the time you do, they’re grown-up enough that they look pretty similar to adults. One of the reasons is that pigeons don’t build nests in trees; they nest in crevices and cliffs. In the city, they nest in little, hidden pockets. There was a deli that I used to stop by on the way home, and sometimes I would hear the baby pigeons calling from behind the sign because there was a flat, warm area back there. It’s neat to realize that there are all these hidden pockets in our architecture that are acting as these nests. Without the ability to listen for the baby pigeons, you might not realize how many little cracks there are in all of our little facades.

Pigeons are often called “rats with wings” by people who presumably aren’t big fans of either rats or pigeons. What do you think it would take for them to get a PR makeover?

There’s some encouraging news, which is that it didn’t take that long for pigeons to fall from grace in our eyes—only a few decades, maybe. Reversing it is totally possible. This hatred is not a deep-set, long-held belief. I think that a lot of it has to do with us understanding landscapes not as permanent, but as things that have changed over time. Once we realize where pigeons fit into that, we are a little more flexible. Their capacity for carrying disease, while not zero, is also way less than we think. I grew up with people saying, “Don’t go up to those pigeons, they’re going to make you sick.”

What I would say for pigeon PR is, look at their long, long, long relationship with us, look at all of the famous people who kept pigeons or loved pigeons or had pigeons influence their work. Look at the war hero pigeons of World War I and World War II. There’s such deep history there. Another thing that always helps is telling people that pigeons are huge romantics and they generally mate for life. That blows people’s minds, because we love romantic stories.

2021 Comedy Wildlife Photography Awards

Lion laughingThe Comedy Wildlife Photography Awards have been unearthing hilarious and heartwarming photos of creatures basically being their best selves since 2015.

And this year is no exception. The recently announced winners and finalists of the 2021 competition include a visibly uncomfortable monkey, a trio of gossipy raccoons, a joyful bird reunion, gravity-defying fish and an all-powerful prairie dog.

A panel of judges sorts through thousands of submissions from expert and novice photographers alike, and determines one winner for each of the several categories — except for the peoples' choice award, which is left up to members of the public. The overall winner gets a handmade trophy from a workshop in Tanzania and a weeklong Kenyan safari.

Read the full article on NPR 

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