Amazon Rainforest birds' bodies transform due to climate change

Date:
November 13, 2021
Source:
Louisiana State University
Summary:
The most pristine parts of the Amazon rainforest devoid of direct
human contact are being impacted by human-induced climate change,
according to new research. New analyses of data collected over the
past four decades show that not only has the number of sensitive
resident birds throughout the Amazon rainforest declined, but
the body size and wing length have changed for most studied
species. These physical changes in the birds track increasingly
hot and dry conditions in the dry season, from June to November.



FULL STORY ==========================================================================
The most pristine parts of the Amazon rainforest devoid of direct human
contact are being impacted by human-induced climate change, according to
new research by LSU scientists. New analyses of data collected over the
past four decades show that not only has the number of sensitive resident
birds throughout the Amazon rainforest declined, but the body size and
wing length have changed for most studied species. These physical changes
in the birds track increasingly hot and dry conditions in the dry season,
from June to November.


========================================================================== "Even in the middle of this pristine Amazon rainforest, we are seeing
the global effects of climate change caused by people, including us,"
said Vitek Jirinec, LSU alumnus (Ph.D. '21), associate ecologist at the Integral Ecology Research Center and lead author to this study published
in the journal Science Advances.

Birds in the Amazon rainforest have become smaller and their wings have
become longer over several generations, indicating a response to the
shifting environmental conditions that may include new physiological or nutritional challenges.

This is the first study to discover these changes in non-migratory
birds' body size and shape, which eliminates other factors that may have influenced these physiological changes. Jirinec and colleagues studied
data collected on more than 15,000 individual birds that were captured, measured, weighed, marked with a leg band and released, over 40 years
of field work in the world's largest rainforest. The data reveal that
nearly all of the birds' bodies have reduced in mass, or become lighter,
since the 1980s. Most of the bird species lost on average about 2 percent
of their body weight every decade. For an average bird species that
weighed about 30 grams in the 1980s, the population now averages about
27.6 grams. How significant is this? "These birds don't vary that much
in size. They are fairly fine-tuned, so when everyone in the population
is a couple of grams smaller, it's significant," said co-author Philip Stouffer, who is the Lee F. Mason Professor in the LSU School of Renewable Natural Resources.

The data set covers a large range of the rainforest so the changes in the birds' bodies and wings across communities are not tied to one specific
site, which means that the phenomenon is pervasive.

"This is undoubtedly happening all over and probably not just with birds," Stouffer said. "If you look out your window, and consider what you're
seeing out there, the conditions are not what they were 40 years ago and
it's very likely plants and animals are responding to those changes as
well. We have this idea that the things we see are fixed in time, but if
these birds aren't fixed in time, that may not be true." The scientists investigated 77 species of rainforest birds that live from the cool,
dark forest floor to the warmer, sunlit midstory. They discovered that
the birds that reside in the highest section of the midstory and are the
most exposed to heat and drier conditions, had the most dramatic change
in body weight and wing size. These birds also tend to fly more than
the birds that live on the forest floor. The idea is that these birds
have adapted to a hotter, drier climate by reducing their wing loading therefore becoming more energy efficient in flight. Think of a fighter
jet with a heavy body and short wings that requires a lot of energy to
fly fast compared to a glider plane with a slim body and long wings that
can soar with less energy. If a bird has a higher wing loading, it needs
to flap its wings faster to stay aloft, which requires more energy and
produces more metabolic heat. Reducing body weight and increasing wing
length leads to more efficient resource use while also keeping cooler
in a warming climate.

LSU alumnus Ryan Burner (Ph.D. '19) conducted much of the analysis that revealed the variation among the groups of birds over the years. Burner,
who is now a research wildlife biologist at the U.S. Geological Survey
Upper Midwest Environmental Sciences Center, is the second author of
this study.

The question of the future capacity of Amazonian birds to deal with increasingly hotter and drier surroundings, especially in the dry season, remains unanswered. The same question can be asked for a lot of places
and species that live at the edges of even more environmental extremes.

"There may be other researchers in other places who have relevant data
from the 1970s and 1980s that could be compared to modern data, because
the bird banding protocol we used is pretty standard. So if you measure
mass and wing, maybe there will be more datasets that will emerge and
we'll be able to get more of an idea of the variation across space and
how it might be changing in different systems," Stouffer said.

========================================================================== Story Source: Materials provided by Louisiana_State_University. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Vitek Jirinec, Ryan C. Burner, Bruna R. Amaral, Richard
O. Bierregaard,
Gilberto Ferna'ndez-Arellano, Ange'lica Herna'ndez-Palma, Erik I.

Johnson, Thomas E. Lovejoy, Luke L. Powell, Cameron L. Rutt,
Jared D.

Wolfe, Philip C Stouffer. Morphological consequences of climate
change for resident birds in intact Amazonian rainforest. Science
Advances, 2021; 7 (46) DOI: 10.1126/sciadv.abk1743 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211113072507.htm

--- up 2 days, 2 hours, 54 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)