Feathers are slippery, complex evolutionary innovations that make flight possible for birds, but in addition to the hard, aerodynamic feathers used for flight, birds also hold a series of feathers. soft, moving between their bodies and the outermost feathers to regulate body temperature.
Using the Smithsonian collection of 625,000 bird samples, Sahas Barve, former Peter Buck Fellow at the Smithsonian National Museum of Natural History, led a new study to study the feathers of over 249 species of Himalayan songbirds, finding found that more birds living at higher altitudes are fluffy down – the kind of feathers that people fill their jackets with – than birds from lower elevations.
Published February 15 in the magazine Ecology, the study also finds that smaller body birds have longer feathers, which lose heat faster than larger birds, depending on the size of the body and thus a thick layer of insulation.
Finding such a clear pattern across so many species highlights the importance of feathers to a bird’s ability to adapt to its environment and suggests that mitigation may be a viable strategy. common to all songbirds, or passerines as researchers know them. In addition, finding that birds from colder environments tend to be lower down may help researchers predict which birds are most vulnerable to change. climate simply by examining the feathers.
The Himalayas are seeing some of the fastest warming rates on Earth. At the same time, climate change is leading to an increase in the frequency and intensity of extreme cold events such as snowstorms. Properly predicting the temperature at which a bird can stand will provide us with a new tool to predict how some species may respond to climate change. “
Sahas Barve, Peter Buck Fellow, National Museum of Natural History, Smithsonian
The search was inspired by a tiny bird called a golden crab on a frigid morning of fieldwork in the Sho-kharkh forest in the Himalayas. Barve found himself wondering how this bird, which weighs about the same as a teaspoon of sugar, managed to get around the treetops in icy air that was already choking its fingers. Pulling his hands back into the kisses of his thick jacket, the question that formed in Barve ‘s mind was “Do Himalayan birds wear down jackets?”
To answer that question, Barve and his co-authors used a microscope to photograph 1,715 specimen breast feathers from Smithsonian collections representing 249 species from cold, high Himalayan mountains.
Barve and his co-authors then used these highly detailed images to determine the length of the curved section of each feather relative to its overall length. The team was able to do this by looking at the wet, wet patch of each feather near its base as opposed to the sharp feathered ends of most feathers.
After carefully recording the relative lengths of these curved sections, Barve analyzed the results and found that the smallest and the smallest birds were from the highest elevations. height, where the temperature is at its coldest, tends to have the highest proportion of their body feathers.
The analysis showed that high-altitude birds were up to 25% more down in their feathers, while the smallest bird had feathers that were three times as long as the larger birds, depending on the size of the bird. their bodies.
Previous research suggested that birds from colder sports habitats applied insulation, but Barve said this was the first study to examine this pattern for such a large number of species in cold environments. and over 15,000 feet of elevation.
“Seeing this correlation across so many species makes our conclusions more general and allows us to say that these results show that all passerine birds can show this pattern, “Barve said.” And we would never have been able to look at so many different species and find this broader evolutionary pattern without Smithsonian collections. “
Carla Dove, who runs the museum’s Feather Recognition Lab and contributed to the study, said she was excited to work with Barve to use Smithsonian collections in a new way. “
Sahas looked at more than 1,700 samples. It’s obvious that they’re all in one place in central Washington, DC, instead of going to the Himalayas and studying these birds in the country, making a big difference. He allowed the required data to be collected quickly before the COVID locks wiped out the globe, and then worked on the remote analysis. “
Barve said he is continuing this study with experiments looking at how much insulation birds get from their feathers and then linking that to the structure of the feathers and the proportion. down. One day, Barve aims to develop a model that will allow scientists to look at the structure of feathers and predict how much insulation it will give the bird – a potential that would help researchers of these species. -closed to climate change.
Dove said the ability to use these results to ultimately understand how some birds might cope with climate change reflects the importance of museum collections.
“Over 620,000 bird samples have been collected over the last 200 years awaiting studies like this. We don’t know what samples we use for down the line; that’s why that we need to maintain and continue to develop them. These examples. from the past can be used to make predictions for the future. “Funding and support for this research was provided by the Smithsonian.