Projected increases in the frequency, intensity and duration of heatwaves in the desert of the southwestern United States are putting songbirds at greater risk for death by dehydration and mass die-offs, according to a new study.
Researchers used hourly temperature maps and other data produced by the North American Land Data Assimilation System (NLDAS) -- a land-surface modeling effort maintained by NASA and other organizations -- a long with physiological data to investigate how rates of evaporative water loss in response to high temperatures varied among five bird species with differing body masses.
Using this data, they were able to map the potential effects of current and future heat waves on lethal dehydration risk for songbirds in the Southwest and how rapidly dehydration can occur in each species.
Researchers homed in on five songbird species commonly found in the desert southwest: lesser goldfinch, house finch, cactus wren, Abert's towhee and the curve-billed thrasher.
Under projected conditions where temperatures increase by 4 degrees Celsius (7 degrees Fahrenheit), which is in line with some scenarios for summer warming by the end of the century, heatwaves will occur more often, become hotter, and expand in geographic range to the point where all five species will be at greater risk for lethal dehydration.
Birds are susceptible to heat stress in two ways, said co-author Blair Wolf, a professor of biology at the University of New Mexico. With funding from the National Science Foundation, Wolf investigated heat tolerance for each of the five species in the study as well as for other bird species in Australia and South Africa. "When it's really hot, they simply can't evaporate enough water to stay cool, so they overheat and die of heat stroke," he said. "In other cases, the high rates of evaporative water loss needed to stay cool deplete their body water pools to lethal levels and birds die of dehydration. This is the stressor we focused on in this study."
What happens is at about 40 degrees Celsius [104 degrees Fahrenheit], these songbirds start panting, which increases the rate of water loss very rapidly, explained co-author Alexander Gerson, an assistant professor of biology at the University of Massachusetts-Amherst. At the time of the study, he worked with Wolf as a postdoctoral researcher at the University of New Mexico. He added, "Most animals can only tolerate water losses that result in 15 or 20 percent loss of body mass before they die. So an animal experiencing peak temperatures during a hot summer day, with no access to water, isn't going to make it more than a few hours."
As expected, they found that the small species are particularly susceptible to lethal dehydration because they lose water at a proportionately higher rate. For example, at 50 degrees Celsius [122 degrees Fahrenheit], the lesser goldfinch and the house finch lose 8 to 9 percent of their body mass to evaporative water loss per hour, whereas the larger Curve-billed thrasher only loses about 5 percent of its mass per hour. By the end of the century, the number of days in the southwest desert where lethal dehydration poses a high risk to the lesser goldfinch increases from 7 to 25 days per year. For larger species, those days will also increase, but will remain rare.
Despite their physiological disadvantage, house finches and lesser goldfinches might actually fare comparatively better, the researchers noted, because they can survive in a number of ecosystems and they have a more expansive range. But desert specialists such as the curve-billed thrasher and Abert's towhee have more specific habitat needs and so have a more limited range, restricted in the United States mostly to the hot deserts of the Southwest. That means that a greater proportion of their population is at risk for lethal dehydration when severe enough heatwaves occur.
"When you get into a situation where the majority of the range is affected, that's where we start to become more alarmed at what we are seeing," said lead author Tom Albright from the University of Nevada, Reno, noting that this increases the risk of lethal dehydration affecting a large proportion of the population.
According to the researchers, given this warming scenario, climate refugia -- microclimates such as mountaintops, trees and washes with shade that allow songbird body temperatures to cool to safe levels -- might prove very important in management plans for certain vulnerable species. "Using this type of data, managers identifying the best refugia can have a better idea of the temperature profile that will be suitable for these birds," Gerson said.
This research is part of a global effort among researchers from the US, South Africa and Australia to more thoroughly understand the physiological responses of birds to increasing temperatures, with the goal of broadening our understanding of how rising temperatures will affect individuals, populations, and community structure. A three-year, $350,000 NASA New Investigator award also funded University of Nevada, Reno-based modeling aspects of this research.
To read the paper, visit:
For more information about NASA Earth science research, visit:
Samson Reiny | EurekAlert!
AWI researchers measure a record concentration of microplastic in arctic sea ice
24.04.2018 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
Climate change in a warmer-than-modern world: New findings of Kiel Researchers
24.04.2018 | Christian-Albrechts-Universität zu Kiel
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
25.04.2018 | Physics and Astronomy
25.04.2018 | Physics and Astronomy
25.04.2018 | Information Technology