Migratory songbirds’ travels disrupted by earlier springs

A scarlet tanager perched on a tree branch. (Photo Credit: Jen Goellnitz/Flickr)

Spring has arrived in North America. Leaves have sprouted, flowers are in bloom and migratory birds are bringing color and song to large swaths of the continent.

The timing of this so-called spring green-up — the beginning of a new cycle of plant growth each year — affects migratory birds’ behaviors and ability to survive their move north. They tend to travel later if winter lasts a little long, and sooner if spring comes early.

In North America, climate change is causing spring to arrive an average of 0.4 days earlier each year. According to a new paper in Nature Ecology and Evolution, some species could be unable to keep pace with this rapid change.

Although a change of less than half a day per year might not sound like much, it adds up to an entire week’s worth of change every 20 years, and it could alter what food is available along their migration routes and breeding grounds, how much time fledglings have to leave the nest, and how the birds interact with other plant and animal species. Previous research has found that such changes could lead to population declines and cascading effects to ecosystems.

“Some birds are quite accurate on the coming of spring because they are highly sensitive to the rhythms and cycles of nature,” said Morgan Tingley, a UCLA ecologist and the paper’s senior author.

Tingley and his co-authors crowdsourced 7 million observations by birdwatchers from the online platform eBird and compared the data to the timing of spring green-up as seen from space via two NASA satellites from 2002 through 2017.

The researchers analyzed how 56 species of migratory birds, primarily small songbirds, responded to these earlier springs. All species travel to breeding grounds in North America but some winter farther south, in the Caribbean, Central America and South America. The authors found that species with shorter, slower migration routes that winter farther north adjusted to changes better — the pine warbler and eastern phoebe, for example. Others had more trouble keeping pace, particularly those that winter in South America and have longer migration routes — such as the bobolink and willow flycatcher.

Most were unable to entirely keep up with an earlier arrival of spring. For each day earlier that green-up occurred, species generally adjusted their migration schedules by less than a half-day.

That inability to adjust to an earlier spring can have serious consequences, said Casey Youngflesh, the study’s lead author and a UCLA ecology and evolutionary biology researcher.

“If birds show up days or weeks later than optimal, they may not have enough food, which could result in lower success breeding and fewer chicks that survive to leave the nest,” Youngflesh said. “That’s really the main concern — that it may cause overall declines in how many birds there actually are.”

The study also notes that the consequences for birds could indirectly affect other animals and even plants. For example, caterpillars are a primary source of food for migratory birds, but if bird populations were to decline, it is possible that more caterpillars than normal would survive each year. Were that to happen, the health of trees could be affected because leaves are a primary food source for caterpillars.

“Everything is interconnected. If you remove a piece of the ecosystem, it’s hard to say exactly what will happen,” Youngflesh said, adding that further research would be needed to determine exactly what the consequences of earlier green-ups would be for any individual species.

Changes in climate have always been a major factor in the evolution of birds’ migratory patterns. However, Youngflesh said, those adaptations have occurred over tens of thousands, or even hundreds of thousands, of years. Modern climate change, largely resulting from increased carbon dioxide emissions, is happening far faster, over years and decades — so rapidly that many species are unable to adapt quickly enough.

That’s thought to be one of the primary reasons bird populations have declined rapidly across North America in recent decades. A 2019 paper published in Science concluded that the number of birds on the continent has diminished by about 3 billion since 1970, when the total population was around 7 billion. In addition to climate change, other factors such as habitat loss, outdoor-dwelling cats and more windows — with which birds collide — are likely reasons for the decline.

The new study, whose co-authors included researchers from the University of Florida, University of North Carolina and Pennsylvania State University and others, outlines a framework for further research into why and how the decline is happening, and it could help conservationists target their efforts to protect the species that are most at risk, Tingley said.

“Climate change is producing winners and losers,” Tingley said. “We are mapping for the first time why some are winning and others are losing.”

This article, written by David Colgan, originally appeared in the UCLA Newsroom.

A photo of the planet Venus.

How long is a day on Venus? Scientists crack mysteries of our closest neighbor

A photo of the planet Venus.

Fundamentals such as how many hours are in a Venusian day provide critical data for understanding the divergent histories of Venus and Earth, UCLA researchers say. (Photo Credit: NASA/JPL-Caltech)

Venus is an enigma. It’s the planet next door and yet reveals little about itself. An opaque blanket of clouds smothers a harsh landscape pelted by acid rain and baked at temperatures that can liquify lead.

Now, new observations from the safety of Earth are lifting the veil on some of Venus’ most basic properties. By repeatedly bouncing radar off the planet’s surface over the last 15 years, a UCLA-led team has pinned down the precise length of a day on Venus, the tilt of its axis and the size of its core. The findings are published today in the journal Nature Astronomy.

“Venus is our sister planet, and yet these fundamental properties have remained unknown,” said Jean-Luc Margot, a UCLA professor of Earth, planetary and space sciences who led the research.

Earth and Venus have a lot in common: Both rocky planets have nearly the same size, mass and density. And yet they evolved along wildly different paths. Fundamentals such as how many hours are in a Venusian day provide critical data for understanding the divergent histories of these neighboring worlds.

Changes in Venus’ spin and orientation reveal how mass is spread out within. Knowledge of its internal structure, in turn, fuels insight into the planet’s formation, its volcanic history and how time has altered the surface. Plus, without precise data on how the planet moves, any future landing attempts could be off by as much as 30 kilometers.

“Without these measurements,” said Margot, “we’re essentially flying blind.”

The new radar measurements show that an average day on Venus lasts 243.0226 Earth days — roughly two-thirds of an Earth year. What’s more, the rotation rate of Venus is always changing: A value measured at one time will be a bit larger or smaller than a previous value. The team estimated the length of a day from each of the individual measurements, and they observed differences of at least 20 minutes.

“That probably explains why previous estimates didn’t agree with one another,” Margot said.

Venus’ heavy atmosphere is likely to blame for the variation. As it sloshes around the planet, it exchanges a lot of momentum with the solid ground, speeding up and slowing down its rotation. This happens on Earth too, but the exchange adds or subtracts just one millisecond from each day. The effect is much more dramatic on Venus because the atmosphere is roughly 93 times as massive as Earth’s, and so it has a lot more momentum to trade.

The UCLA-led team also reports that Venus tips to one side by precisely 2.6392 degrees (Earth is tilted by about 23 degrees), an improvement on the precision of previous estimates by a factor of 10. The repeated radar measurements further revealed the glacial rate at which the orientation of Venus’ spin axis changes, much like a spinning child’s top. On Earth, this “precession” takes about 26,000 years to cycle around once. Venus needs a little longer: about 29,000 years.

With these exacting measurements of how Venus spins, the team calculated that the planet’s core is about 3,500 kilometers across — quite similar to Earth — though they cannot yet deduce whether it’s liquid or solid.

Venus as a giant disco ball

On 21 separate occasions from 2006 to 2020, Margot and his colleagues aimed radio waves at Venus from the 70-meter–wide Goldstone antenna in California’s Mojave Desert. Several minutes later, those radio waves bounced off Venus and came back to Earth. The radio echo was picked up at Goldstone and at the Green Bank Observatory in West Virginia.

“We use Venus as a giant disco ball,” said Margot, with the radio dish acting like a flashlight and the planet’s landscape like millions of tiny reflectors. “We illuminate it with an extremely powerful flashlight — about 100,000 times brighter than your typical flashlight. And if we track the reflections from the disco ball, we can infer properties about the spin [state].”

Muhammad Nadeem, Jean-Luc Margot/UCLA and NASA

The complex reflections erratically brighten and dim the return signal, which sweeps across Earth. The Goldstone antenna sees the echo first, then Green Bank sees it roughly 20 seconds later. The exact delay between receipt at the two facilities provides a snapshot of how quickly Venus is spinning, while the particular window of time in which the echoes are most similar reveals the planet’s tilt.

The observations required exquisite timing to ensure that Venus and Earth were properly positioned. And both observatories had to be working perfectly — which wasn’t always the case. “We found that it’s actually challenging to get everything to work just right in a 30-second period,” Margot said. “Most of the time, we get some data. But it’s unusual that we get all the data that we’re hoping to get.”

Despite the challenges, the team is forging ahead and has turned its sights on Jupiter’s moons Europa and Ganymede. Many researchers strongly suspect that Europa, in particular, hides a liquid water ocean beneath a thick shell of ice. Ground-based radar measurements could fortify the case for an ocean and reveal the thickness of the ice shell.

And the team will continue bouncing radar off of Venus. With each radio echo, the veil over Venus lifts a little bit more, bringing our sister planet into ever sharper view.

This research was supported by NASA, the Jet Propulsion Laboratory and the National Science Foundation.

Other researchers who contributed to the study are Donald Campbell of Cornell University; Jon Giorgini, Joseph Jao and Lawrence Snedeker of the Jet Propulsion Laboratory; and Frank Ghigo and Amber Bonsall of the National Radio Astronomy Observatory in West Virginia.

This article, written by Christopher Crockett, originally appeared in the UCLA Newsroom.

A photo of Ayad Akhtar

Pulitzer Prize winner Ayad Akhtar to speak at UCLA’s Luskin Lecture for Thought Leadership, May 13

A photo of Ayad Akhtar

Akhtar won the 2013 Pulitzer Prize for drama for his Tony-nominated play “Disgraced.” (Courtesy of the Tuesday Agency)

Pulitzer Prize-winning author Ayad Akhtar will speak at the Luskin Lecture for Thought Leadership on Thursday, May 13 at 4 p.m. Following his remarks, Akhtar will take part in a conversation with Ali Behdad, UCLA’s John Charles Hillis Professor of Literature.

The online event is free and open to the public.

“This is an exciting opportunity to hear from one of the most creative and brilliant literary minds of our time,” said David Schaberg, senior dean of the UCLA College. “Ayad Akhtar is an outstanding storyteller and an incisive observer of the human experience, and we are honored to have him share his insights with us.”

Akhtar won the 2013 Pulitzer Prize for drama for his Tony-nominated play “Disgraced.” His other plays include “Junk,” which won the Edward M. Kennedy Prize for American Drama Inspired by American History and was nominated for a Tony, and “The Invisible Hand,” which earned an Obie Award, Outer Critics Circle’s John Gassner Award and Olivier Award.

Akhtar’s latest work is the novel “Homeland Elegies,” which explores the experiences of a Muslim man who, like the author, grew up in Wisconsin as the son of Pakistani immigrants. The Washington Post called it “a tour de force” and The New York Times noted it was “a beautiful novel … that had echoes of ‘The Great Gatsby’ and that circles, with pointed intellect, the possibilities and limitations of American life.”

Jennifer Mnookin, dean of the UCLA School of Law was one of the four UCLA deans who collectively chose to invite Akhtar to speak. She said “Homeland Elegies” was “the single most affecting, inspiring book” she has read during the pandemic.

“It is an extraordinary novel about the complexity of America, a beautiful interweaving of fact and fiction that explores identity, immigration, Islamophobia after 9/11, the process of literary creation and so much more,” Mnookin said. “It’s both a novel of ideas and a page turner.”

Akhtar’s first novel, “American Dervish,” has been published in more than 20 languages.

In 2017, Akhtar received an Arts and Letters Award for literature from the American Academy of Arts and Letters, the Steinberg Playwright Award and the Nestroy Theatre Prize. He has received fellowships from the American Academy in Rome, MacDowell, the Sundance Institute and Yaddo, for which he is also a board director. He is president of PEN America, the national nonprofit writers organization, and a board trustee at New York Theatre Workshop.

Visit the Luskin Lecture for Thought Leadership website to register for the livestream, learn more about the event and submit a question for the speaker.

The Luskin Lecture for Thought Leadership was established in 2011 through a generous gift from Meyer and Rene Luskin. Their vision in establishing the lecture series gave UCLA an opportunity to share knowledge and foster dialogue among scholars, leaders in government and business, and the greater Los Angeles community.

This article, written by Margaret MacDonald, originally appeared in the UCLA Newsroom