Aussie birds turn down their thermostat to save energy in winter

JUNE 27, 2019

by Western Sydney University

Research published in Biology Letters by scientists at Western Sydney University provides the first clear evidence that a species of perching bird (the passerines) can employ torpor—an energy-saving mechanism whereby the body temperature of an animal is temporarily reduced in a controlled way during resting.

In this new research, the authors used miniature radio-transmitters to record the skin temperature of these tiny eight-gram birds over several weeks during winter in woodland near Sydney. Skin temperature provided a close approximation of body temperature in such small animals. Remarkably, they showed these fairy-wrens allow their body temperature to decrease substantially during their nightly roosting phase. These periods of nocturnal torpor closely resemble the torpor that is well-known in some small mammals and in a few non-passerine bird groups like hummingbirds. This new evidence of regular use of torpor by a passerine bird is important for understanding the physiology and ecology of birds.

Birds are typically small and light, which helps them to fly and escape from predators but means they cannot carry a lot of fat and this presents a challenge during winter when food is hard to find. The use of torpor provides a very effective mechanism to reduce the amount of energy required for thermoregulation when resting during the night. Torpor could be an important strategy allowing small birds to cope with limited and fluctuating food supplies.

"Even in a relatively mild climate, superb fairy wrens benefit from the energy-savings that nocturnal torpor provides," said Dr. Christopher Turbill from the Hawkesbury Institute for the Environment at Western Sydney University.

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60 PERCENT OF BIRD SPECIES CAME FROM AUSTRALIA

POSTED BY GIGI MARINO-FLORIDA

All perching birds—the majority of the world’s bird population—originated in Australia, researchers report.

These birds—also known by their order name, passerines—comprise more than 6,000 species, including familiar birds like cardinals, warblers, jays, and sparrows. Passerines make up more than 60 percent of all feathered friends known to humankind.

While scientists know a lot about their birdsong, mating rituals, and anatomy, they haven’t fully understood the origin of passerines, which determines how different species developed and their relationship to one another. It turns out, according to the new research, that sweet Carolina wren at your feeder actually has a very long-lost ancestor, 47 million years ago or so, in the land Down Under.

SPREADING ACROSS THE WORLD

Previous hypotheses about passerine evolution and diversification purported that perching birds originated from South America. Now a clearer picture of an Old World origin and patterns of movement that global climate change, mass extinction, or the colonization of new continents influenced has come into focus.

The researchers conducted genomic testing using technology that did not exist 10 years ago. They analyzed DNA data from the 137 families of perching birds. Some of the museum samples the researchers used were up to 100 years old.

“Previous studies only looked at one or a few genes,” says Edward Braun, a professor of biology at the University of Florida. “What makes this study unique is one, the broad sampling across the genome, and two, the comprehensive nature in that we captured all major groups of perching birds. The third factor is the integration of the fossil records and biogeography, along with the comprehensive genomic sampling.”

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Scientists explore causes of biodiversity in perching birds

Date:  April 5, 2019

Source:  University of Tennessee at Knoxville

New research by a global team of scientists has resulted in significant strides in ornithological classification and identified possible causes of diversity among modern bird species.

The study, coauthored by researchers at the University of Tennessee, Knoxville and published in Proceedings of the National Academy of Sciences, focuses on perching birds, or passerines. Comprised of over 6,000 species, this group -- which constitutes over half of all known bird species -- includes familiar birds such as robins, jays, bluebirds, finches, and sparrows.

Scientists analyzed genetic samples and fossils of all major groups within the passerine family to better understand the way these species are related. The large data set allowed for much more accurate inferences into the development of perching birds.

The result is the most accurate and comprehensive "tree of life" of passerine species to date.

The report also includes an analysis of the impact some events in Earth's history could have had on passerines' biodiversity.

"Our main discovery is that the evolution of perching birds around the world was determined in part by connections between continents over the Earth's history, as well as changes in global climate," said Michael Harvey, a postdoctoral fellow with UT's Department of Ecology and Evolutionary Biology. "We found, for example, evidence that glaciations during the Oligocene Epoch (between 24 and 33 million years ago) wiped out a lot of perching birds, but that the warming period immediately after prompted the evolution of many of the groups of perching birds alive today."

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Scientists construct new family tree for perching birds

APRIL 1, 2019

by Louisiana State University

Scientists have reconstructed the tree of life for all major lineages of perching birds, also known as passerines, a large and diverse group of more than 6,000 species that includes familiar birds like cardinals, warblers, jays and sparrows. Louisiana State University (LSU) researchers led the massive project using 221 bird specimens from 48 countries, including 56 tissue samples from the LSU Museum of Natural Science's Collection of Genetic Resources. Using these samples, they extracted and sequenced DNA representing all passerine families, and they used these sequence data to understand how passerine species are related and to study when and how passerines diversified in relation to Earth's history.

"In addition to inferring how these species are related, our in-depth study found that changes in global temperature or colonization of new continents were not the sole drivers of passerine diversification, as previously suggested. Instead, our results indicate more complex mechanisms were at play to spark bursts of passerine speciation around the globe," said lead author Carl Oliveros, a postdoctoral researcher in the Department of Biological Sciences at LSU.

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