ºÚÁϳԹÏÍø researchers have identified ways in which low-frequency noise in our environment coming from sources such as ACs and water pumps can trigger blood vessel damage to kidneys in mice.

Close your eyes and just listen for a few seconds. No matter where you are, countless low and deep rumblings are feeding into your ear, coming from AC units, elevator motors, distant traffic, and ventilation ducts.

These rumbles form low-frequency noise below 100 hertz, about the same pitch as a kick drum. Almost all its sources are human made. So they¡¯re a relatively new environmental effect; Living things weren¡¯t meant to be immersed in this kind of noise.

Previous studies have hinted that people who are surrounded with more environmental noise tend to have worse kidney function. But these studies could not point out which part of the noise was to blame, or the specific ways in which it might affect kidneys.

Now, a team led by Takumi Kagawa and Masashi Kato at the have provided the first direct experimental evidence that the low-frequency component of environmental noise is the culprit for adverse kidney health in mice. Their findings were published in the journal .

Pitch matters more than volume

Kagawa and Kato first started by recording real noise from two ordinary household machines: the outdoor unit of an air conditioner and a heat pump water heater. Using audio software, they then split each recording in two: a low-frequency version containing only sounds at or below 100 hertz, and a high-frequency version containing everything above it.

Mice were played these sounds for 12 hours a day over five days, during nighttime when they are naturally active. The researchers then measured two standard markers of kidney health in the animals’ blood, creatinine and urea nitrogen, which build up when the kidneys stop filtering waste efficiently.

Playing the unedited environmental noise symphony containing all frequencies pushed both markers up, signifying kidney damage. But when only the high-frequency noise was played, nothing happened. This meant the lower frequencies were responsible for pushing up the creatinine and urea nitrogen levels, as the researchers soon verified.

¡°The biggest surprise to me was that the low-frequency component caused kidney dysfunction even though it was below the hearing range of mice,¡± Kagawa said. ¡°In contrast, the higher-frequency component did not cause kidney dysfunction, even when both had the same physical sound pressure level,¡± he added, implying that the frequency of noise mattered more than its loudness.

Squeezed blood vessels

To find out the modus operandi, the researchers looked inside the kidneys. Kidneys clean the blood using a vast network of glomeruli¡ªtiny knots of blood vessels that act as the organ’s filters. In the exposed mice, these filters were swollen and their delicate filtering membranes had thickened.

Additionally, the damaged kidneys were producing more endothelin-1, a molecule that can bind to receptors to clamp down blood vessels. Under normal conditions, endothelin-1 helps regulate blood flow. But researchers suspected that low-frequency noise can push it into overdrive, causing constricted renal blood vessels

To test this idea, the researchers gave a second group of mice ambrisentan, a drug already prescribed to human patients to treat hypertension, which blocks endothelin’s effects. The treated animals kept their kidney markers closer to normal and showed much less damage to their glomeruli, confirming endothelin signaling as a key pathway.

Because this study was conducted in mice, its relevance to humans remains unknown. However, ¡°our findings highlight the importance of considering low-frequency noise, which has often been overlooked, in future human studies on environmental noise,¡± Kato said.

A double-edged sword

The result is also intriguing because the same researchers have also found some beneficial effects of low-frequency sound, such as reducing motion sickness and blood flow in skin blood vessels.

This suggests that ¡°the biological effects of low-frequency sound depend on its frequency, sound level, and duration of exposure,¡± Kato said. ¡°Moving forward, we hope to investigate both the beneficial and adverse effects of low-frequency sound and scientifically clarify which exposure conditions are harmful and which promote health.¡±

Publication Information:

Takumi Kagawa, Dijie Chen, Nobutaka Ohgami, Keming Tong, Yanjun Gao, Naruhito Iwasaki, Akihito Harusato, Toyonori Tsuzuki, Takumi Hayashi, Yuuki ?Shimizu, Toyoaki Murohara, and Masashi Kato, 2026. Glomerular Injury Induced by Daily Exposure to the Low-Frequency Component of Environmental Noise via Endothelin Signaling in Mice, Environmental Science & Technology.?DOI:

Funding Information:

This work was supported partly by Grants-in-Aids for Scientific Research (B) (22K11731, 23H03147, 25K02875, and 23K27837), Challenging Research (Exploratory) (25K22731, 25K22732, 25K22741), Young Research (24K19748, 26K20515), and Fund for the Promotion of Joint International Research (22KK0145) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Grant-in Aid for JSPS Research Fellow (22J22680 and 22KJ1602) from Japan Society for the Promotion of Science, Frontier Next-Generation Researcher Program of the Tokai Higher Education and Research System (JPMJSP2125) from JST SPRING and JKA and its promotion funds from KEIRIN RACE (2023M-407). The funders had no role in the study design, data collection and analysis, decision to publish, or manuscript preparation.

Expert contact:

Masashi Kato
Department of Occupational and Environmental Health,
ºÚÁϳԹÏÍø
Email: kato.masashi.r6@f.mail.nagoya-u.ac.jp

Media contact:

Sumeet Kulkarni 
International Communications Office 
ºÚÁϳԹÏÍø 
Email: icomm_research@t.mail.nagoya-u.ac.jp 

Top Image:

Visual representation of low-frequency environmental noise coming from climate control systems. Credit: Sumeet Kulkarni, ºÚÁϳԹÏÍø.

1. Period of Closure

• Saturday, August 8, 2026 ¨C Sunday, August 16, 2026

2. Organizations

• Tokai National Higher Education and Research System
• ºÚÁϳԹÏÍø
  • ºÚÁϳԹÏÍø Hospital will be open as usual.
  • Please check the ºÚÁϳԹÏÍø Library for opening hours.
• Gifu University
  • Gifu University Hospital will be open as usual.

Message from the President regarding the 2026 Kumamoto Earthquake

On behalf of ºÚÁϳԹÏÍø, I would like to express our deepest condolences to those who lost their lives in the 2026 Kumamoto Earthquake, and extend our heartfelt sympathies to all those affected, their families, and everyone concerned.

We sincerely pray for the speedy recovery of those affected, as well as for the earliest possible restoration and reconstruction of the affected areas.

July 31, 2026
Naoshi Sugiyama
President of ºÚÁϳԹÏÍø

To all students: Support measures related to the 2026 Kumamoto Earthquake

We would like to express our deepest sympathies to everyone affected by the “2026 Kumamoto Earthquake.” If you or a member of your family has been seriously affected by the earthquake and you require academic support or special accommodations, please contact the academic affairs office of your faculty or graduate school, or the Education Planning Division of the Education & International Affairs Department.

It is natural to feel anxious or distressed after experiencing such an event. If these feelings persist, please do not hesitate to contact the Student Counseling Center.

Please be aware that false or misleading information may circulate on social media and other platforms. Be sure to rely on official sources for the latest and most accurate information.

Education & International Affairs Department, ºÚÁϳԹÏÍø

Contact
Education Planning Division, Education & International Affairs Department, ºÚÁϳԹÏÍø
Email: kyomu[at]t.mail.nagoya-u.ac.jp

Contact list for each undergraduate/graduate school and the Institute of Liberal Arts and Sciences (PDF)

Student Counseling Center, Student Support, ºÚÁϳԹÏÍø
Email: soudan[at] gakuso.provost.nagoya-u.ac.jp

Dispatch of staff to support disaster-affected areas due to the 2026 Kumamoto Earthquake

To assist with assessing damage to school facilities in areas affected by the 2026 Kumamoto Earthquake and conducting emergency safety assessments, staff members were dispatched at the request of the Ministry of Education, Culture, Sports, Science and Technology (MEXT).

Dispatch Overview
Dispatch Period: August 5-8, 2026
Dispatch Team: Emergency Safety Assessment Team
(Three members from Tokai National Higher Education and Research System, Gifu University, and ºÚÁϳԹÏÍø)

Activities
Assessment of damage to school facilities
Emergency safety assessments of school facilities
Support for safety inspections of facilities in disaster-affected areas

Tokai National Higher Education and Research System will continue to support recovery and reconstruction efforts in cooperation with relevant organizations.

Last updated: August 5, 2026

Researchers at ºÚÁϳԹÏÍø in Japan have created an innovative treatment for periodontitis that targets and eliminates harmful bacteria while preserving beneficial oral microbes essential for health. The findings were published in the

Oral health relies on a diverse and balanced microbial community. Porphyromonas gingivalis (P. gingivalis) is a keystone pathogen that triggers inflammation and disrupts this balance. Such disruption can damage the bone supporting teeth and eventually lead to tooth loss.

“Current treatments for periodontitis, including antibiotics and antimicrobial photodynamic therapy (aPDT), eliminate both pathogenic and beneficial oral bacteria,” said , one of the corresponding authors and a lecturer at ºÚÁϳԹÏÍø. “These approaches often disrupt the entire oral microbial ecosystem and can also release lipopolysaccharide (LPS), an endotoxin that may exacerbate inflammation.”

To address these challenges, researchers from ºÚÁϳԹÏÍø Graduate School of Medicine, including first author Hiroshi Maruyama, Professor , and corresponding authors Sato and , adapted near-infrared photoimmunotherapy, a technique originally developed for cancer treatment. This method uses an antibody-dye compound that binds to target cells and is activated by near-infrared light.

Expanding on this therapy, the team developed a method using IgY, an antibody from egg yolks of hens immunized against P. gingivalis. Because IgY can be produced in large quantities at low cost, it offers significant clinical potential. The researchers evaluated this new approach, called near-infrared photo-antibacterial targeting therapy (NIR-PAT?), in human cell cultures and mice to eliminate P. gingivalis while preserving a healthy oral environment, comparing its performance to conventional therapies.

Selective elimination of pathogens without damaging healthy tissue

In cell culture experiments, the antibody-dye compound selectively bound to P. gingivalis, leaving other bacteria and healthy human gum cells unaffected. When exposed to near-infrared light, the dye accumulated on P. gingivalis, disrupted its outer membrane, and eliminated the bacterium.

Microscopic analysis showed that treated P. gingivalis developed small membrane holes but retained its overall structure, while aPDT resulted in complete bacterial destruction. Tests confirmed that the new therapy did not harm human gum cells, whereas aPDT caused cellular injury and delayed healing.

Reduction of bone loss and improved oral microbiota in mouse models

In mouse models of periodontitis, the new treatment significantly reduced alveolar bone loss. Saliva analysis indicated that the therapy improved oral microbiota by eliminating pathogenic P. gingivalis while preserving beneficial Streptococcus populations. In comparison, standard antibiotics and aPDT removed both pathogenic and beneficial bacteria, further disrupting the oral microbiota.

“Results demonstrated that, unlike antibiotics or standard light therapy, this approach selectively removes the primary pathogenic species while preserving the remainder of the oral bacterial community,” Sato said.

To achieve clinical application

The researchers explain that periodontitis is caused by several types of bacteria, so focusing on just one may not be enough. They intend to use artificial intelligence (AI) to analyze publicly available oral bacteria data to identify other important species and better understand how they interact. These insights will help develop more precise treatments.

Because periodontitis is connected to health issues such as rheumatoid arthritis and diabetes, the researchers believe that their AI-driven analysis could also help determine which patients are most likely to benefit from targeted treatments.

Publication information

Hiroshi Maruyama, Kazuhide Sato, Kiyoshi Sakaia, Hirotoshi Yasui, Ryu Okada, Li Xinheng, Koji Umeda, Shofiqur Rahman, Van Sa Nguyenf, and Hideharu Hibi, 2026. Near infrared photo-bacterialflora modulation technology realized controlling periodontitis: Modulation of disease-associated dysbiosis in oral microbiota using near infrared photo-antibacterial targeting therapy (NIR-PAT?), Journal of Translational Medicine

Expert contact

Kazuhide Sato
ºÚÁϳԹÏÍø Graduate School of Medicine
Email: sato.kazuhide.k5@f.mail.nagoya-u.ac.jp

Media contact

Naomi Inoue
ºÚÁϳԹÏÍø International Communications Office
Email: icomm_research@t.mail.nagoya-u.ac.jp

Top image

NIR-PAT? uses an antibody linked to a light-sensitive dye to find and bind only to P. gingivalis, the key bacterium that drives gum disease, and destroys it when exposed to near-infrared light. This targeted attack removes the harmful bacterium while leaving good bacteria untouched, helping restore a healthy balance in the oral microbiome.
Credit: Kazuhide Sato et al., Journal of Translational Medicine, 2026. Volume 24, Journal of Translational Medicine, licensed under CC BY-NC-ND 4.0

What enables us to sustain effort toward goals, even when the task becomes increasingly difficult? A recent study by researchers at ºÚÁϳԹÏÍø in Japan revealed the underlying brain mechanism, showing that orexin neurons play a crucial role in driving and regulating motivated behavior. The findings were published in .

Motivational deficits, including loss of motivation, are often seen in mental disorders such as depression, addiction and ADHD. However, the brain mechanisms behind these problems remain largely unclear.

The research team, led by , associate professor, and Kiyofumi Yamada, professor emeritus, at ºÚÁϳԹÏÍø’s , focused on orexin neurons. These neurons regulate essential physiological functions such as sleep, appetite and energy expenditure. Although recent studies suggest that orexin neurons also influence motivation, their exact role has remained unclear.

This study used rats to examine how changes in orexin neuron activity influence motivation to obtain food rewards. While most previous studies used mice, rats offer superior learning abilities and are better suited for complex behavioral experiments. Because of technical challenges in targeting specific neurons in rats, research in this area has been limited.

To address this limitation, the team developed genetically modified “orexin-Cre” rats, allowing precise targeting and manipulation of orexin-producing neurons. This model was used to investigate how these neurons influence motivation.

First, using chemogenetics, the researchers activated the rats’ orexin neurons and had them perform a progressive ratio test where the number of touches required to earn a food reward increased with each trial. The point at which a rat gave up (the breakpoint) measured motivation intensity. Rats with activated orexin neurons showed higher breakpoints, meaning they worked harder for the reward. Conversely, in a model where orexin neurons were selectively degenerated, breakpoints were lower, indicating reduced motivation.

Next, using fiber photometry, the team recorded real-time activity of orexin neurons as the rats anticipated and received their reward. Activity increased before the reward was obtained, decreased once it was received, and remained elevated when an expected reward failed to arrive. Notably, the more effort required, the stronger the orexin neuron activity became. The researchers say this pattern may reflect how the brain links reward expectation to the effort required to pursue them.

To test this causally, the researchers used optogenetics to control orexin neuron activity at the moment a reward was anticipated. When orexin neuron activity was suppressed using an inhibitory protein, the rats’ motivated behavior decreased ¡ª they took longer to complete effort-based tasks, and their breakpoints dropped. By contrast, when the team attempted to boost orexin neuron activity at that moment using an excitatory protein, no further increase in motivated behavior was observed, even though the stimulation reliably activated the neurons.

In other words, suppressing orexin neurons impaired motivation, but artificially exciting them beyond natural levels did not enhance it. The researchers say this asymmetry suggests orexin neurons are necessary for sustaining motivated behavior, though simply raising their activity may not be sufficient to increase it. Further studies are needed to determine what governs this effect, such as the duration or pattern of orexin neuron activity.

Mizoguchi concluded, “Our study demonstrated significant changes in orexin neuron activity depending on expected rewards and the effort required, suggesting a potential mechanism for translating expectations into sustained action.”

Future research will investigate the input and output circuits connected to orexin neurons. A deeper understanding of orexin function may inform new approaches to addressing motivational deficits, including loss of motivation or challenges in sustaining goal-directed behavior.

Publication information

Yutao Dong, Sheikh Mizanur Rahaman, Wenjun Zhu, Ayumu Inutsuka, Daisuke Ono, Rinako Tanaka, Tetsuo Matsuzaki, Eiji Shibata, Madoka Isobe, Shuntaro Izawa, Akihiro Yamanaka, Kiyofumi Yamada, and Hiroyuki Mizoguchi, 2026. Reward prediction is encoded by orexin neuron activity during motivated behavior, Proceedings of the National Academy of Sciences of the United States of America,

Funding information

This work was supported by Grant-in-Aid for Scientific Research [22K19749; 23K27360; and 23H02669 (2023)]; SENSHIN Medical Research Foundation; Naito Foundation, Japan; Takeda Science Foundation, Japan; SRF, Japan; Asahi Glass Foundation, Japan; Mishima Kaiun Memorial Foundation, Japan; Kao Health Science Foundation, Japan; and AMED, Japan (JP21wm0425014).

Expert contact

Hiroyuki Mizoguchi
ºÚÁϳԹÏÍø Graduate School of Medicine
Email: mizoguchi.hiroyuki.d5@f.mail.nagoya-u.ac.jp

Media contact

Naomi Inoue
ºÚÁϳԹÏÍø International Communications Office
Email: icomm_research@t.mail.nagoya-u.ac.jp

The ºÚÁϳԹÏÍø Fall 2026 Entrance Ceremony will be held as follows:

• Date and Time: Thursday, October 1, 2026
• Start Time: 10:30 a.m. (Please enter the auditorium by 10:15 a.m.)
• Venue: Toyoda Auditorium, ºÚÁϳԹÏÍø
• Eligible Participants: Students enrolling in October 2026 (Both undergraduate and graduate students, including internal candidates advancing to higher degree programs).

Live Streaming

• The ceremony will be live-streamed for family members and individuals living overseas or in distant areas.
• The link to the live broadcast will be posted on this page prior to the start of the ceremony.

Important Notices

• The ceremony will be conducted in English.
• Ample seating is available; family members, faculty, and staff are welcome to attend the ceremony at the Toyoda Auditorium.
• Please refrain from attending if you are experiencing a fever or other cold-like symptoms.
• Commuting to the campus by car, motorcycle, or other vehicles is strictly prohibited. Please use public transportation. Additionally, please do not park in the parking lots of nearby convenience stores or commercial facilities.
• If you require special assistance due to a disability, please contact your respective undergraduate or graduate school in advance.

Contact Information

• General Administration Division, Education & International Affairs Department, ºÚÁϳԹÏÍø
• Phone: +81-(0)52-789-2159

Date and Time: Friday, September 25, 2026

Starts at 10:30 a.m. (Please enter the auditorium by 10:15 a.m.)

Venue: Toyoda Auditorium, ºÚÁϳԹÏÍø

Eligible Participants: Students graduating from undergraduate and graduate schools in September 2026

*Details regarding the degree conferral ceremonies for individual undergraduate and graduate schools will be announced separately by the respective schools.

Live streaming

The ceremony will be live-streamed for family members and those unable to attend in person.
The link to the live stream will be posted on this page before the ceremony begins.

Important Notices

• The ceremony will be conducted in English.
• Sufficient seating is available; therefore, family members, faculty, and staff are welcome to attend the ceremony in the Toyoda Auditorium.
• Individuals experiencing a fever or other cold-like symptoms are asked to refrain from attending.
• Vehicle access (cars, motorcycles, etc.) to the university campus is strictly prohibited. Please use public transportation. Do not park in the parking lots of nearby convenience stores or other local businesses.
• If you have a disability and require special assistance, please contact your respective undergraduate or graduate school in advance.

Contact
General Administration Division, Education & International Affairs Department, ºÚÁϳԹÏÍø
Phone: +81-(0)52-789-2159

Researchers at ºÚÁϳԹÏÍø have created new chiral nanocarbons with unusual shapes and properties, including a double helix and molecules that emit spiraling light. 

Nanocarbons are molecular-scale carbon structures considered to be the building blocks for next-generation materials. Until now, scientists have built them by fusing small, flat carbon molecules together at their edges. Modifying the inside of a molecule was considered challenging because inner bonds are locked into flat, rigid structures that resist change.?

Researchers at ºÚÁϳԹÏÍø in Japan have shown that a chemical process focused on the interior of a molecular structure can create chiral nanocarbons. Like our hands, these molecules exist in mirror-image left- and right-handed forms. The method, known as skeletal editing, allowed the research team to cut and reform bonds inside common flat carbon molecules, such as small pieces of graphene. They could then build new chiral nanocarbons in various shapes, including molecules with 10-carbon rings and a double helix.  

These new molecules do surprising things. They all glow with light that spirals as it travels. Two can hold multiple electrical charges without breaking. One of them also keeps its handed shape even at 280 degrees Celsius. Another assembles into a porous crystal that can trap and release carbon dioxide, a property that could be useful for gas storage materials. 

Skeletal editing has mainly been used by chemists to manufacture pharmaceuticals. This is the first time it has been applied to nanocarbon synthesis. The approach solved two persistent challenges. First, the researchers built a 10-carbon ring into large chiral nanocarbons, a combination not achieved before. Second, they showed that both left- and right-handed forms of complex nanocarbons can be produced (asymmetric synthesis), a feat only accomplished twice before with nanocarbons of this size. The findings were published in . 

¡°If you alter the inside of a molecule, it causes significant strain, so most reactions proceed around the molecule instead. Over time, this led to the assumption that the interior could not be modified,¡± said senior author Norihito Fukui, Associate Professor at the , ºÚÁϳԹÏÍø. ¡°However, with the right method and the right starting molecule, we can change the inside and create molecular shapes and structures that could not be made before.”  

Most nanocarbons are built from flat structures consisting of six-sidedrings, like small pieces cut from graphene. Carbon atoms naturally prefer to form these shapes because of the angles their bonds make. Chemists have recently found ways to include seven- and eight-sided rings. However, ten-sided rings and non-flat arrangements of six-sided rings have remained very difficult to build.

The double-helix molecule is made by cutting and reforming a bond. It self-assembles into crystals with spiral-shaped pores that trap and release carbon dioxide. This chiral porous material is the first of its kind. It is a cousin of the metal-organic frameworks (MOFs) that won the 2025 Nobel Prize in Chemistry.

Molecules of a new twisted double-helical nanocarbon stack together into spirals that form chiral pores. The pores can trap and release carbon dioxide. Red and blue mark neighboring spirals of stacked molecules. Credit: Hirano et al., Nature Communications 2026 

The unique properties of these chiral molecules are what scientists look for when they design advanced materials for gas storage, ultra-low-power electronics, and next-generation encryption.

The findings extend skeletal editing beyond its traditional territory in pharmaceuticals. ¡°We hope the approach will inspire other researchers to investigate what else can be built by editing the interior of molecules,¡± Fukui said.  

Publication information:

Junichiro Hirano, Tomoyuki Ikai, Shinpei Kusaka, Ryotaro Matsuda, Hiroshi Shinokubo, Norihito Fukui, 2026. Skeletal transformation to chiral nanocarbon molecules, Nature Communications, 17: 6052. DOI:

Funding information: 

This work was supported by JSPS KAKENHI grants JP20H05862, JP20H05863, JP20H05867, JP23H03947, JP24K01467, JP24K21766, JP25H01265, and JP26H00381, as well as JST PRESTO grant JPMJPR21Q7 and JST FOREST grant JPMJFR232G. 

Expert contact: 

Norihito Fukui 
Graduate School of Engineering 
ºÚÁϳԹÏÍø 
E-mail: fukui@chembio.nagoya-u.ac.jp 

Media contact: 

Merle Naidoo
International Communications Office
ºÚÁϳԹÏÍø
Email: icomm_research@t.mail.nagoya-u.ac.jp 

Top image:

A new family of chiral nanocarbons shaped like a figure-eight (top middle), a bathtub (bottom left) and double helix (bottom right). Chiral molecules exist in left- and right-handed forms, like a pair of hands. Researchers used skeletal editing to build these complex carbon molecules. The double-helix molecule also self-assembles into crystals with chiral pores that trap and release carbon dioxide. Credit: Graduate School of Engineering, ºÚÁϳԹÏÍø 
 
 
 
 

A field experiment on wild kittiwakes in Alaska reveals how short-term energy demands ripple across the year, with consequences for future reproduction and survival.

 
Wild seabirds that face high energy demands during the breeding season go on to migrate farther and raise more chicks the next year, but at a cost to their own survival. An international team, led by researchers from ºÚÁϳԹÏÍø, raised the energy cost of flight for some birds and tracked them through the next year of their annual cycle. The researchers introduce a concept called “energetic flexibility” and offer rare experimental evidence for how the costs of one season carry over to shape the next. The study appears in . 
 
The team studied 251 black-legged kittiwakes on Middleton Island, Alaska, from 2021 to 2024. In 2021, they altered the energy cost of breeding for three groups. One group received extra food, which reduced the energy cost of raising chicks. For a second group, the team clipped three wing feathers and two tail feathers at the base shortly after the birds had laid their eggs. This raised the energy cost of flight for the rest of the breeding season. The feathers grew back at the birds’ next molt. A third group was left alone as a control. 
 
Each bird carried a geolocator that recorded its movements through the non-breeding season. The team recovered 203 of the 251 devices the next year and tracked the same individuals through 2024. 
 
Birds with raised energy costs fledged only 10% of their chicks that year. The fed group and the control group did much better: 44% and 43% respectively. The high-cost birds also departed about 10 days earlier than the other groups, leaving the colony at the end of the breeding season to head out to sea for the long migration across the North Pacific Ocean. ? 

¡°Earlier departure from the breeding colony by birds that failed to raise chicks has long been recognized. However, our study demonstrates that early departure is driven not by breeding success or failure itself, but by the energetic costs incurred during reproduction,¡± said Akiko Shoji, senior author and professor at the , ºÚÁϳԹÏÍø. In other words, breeding failure appears to be one consequence of high energetic costs, rather than the direct cause of early departure.¡± 
 
Their earlier departure also resulted in longer migrations. Birds that travelled farther during the non-breeding season were more likely to breed successfully the following year. This suggests that longer migrations may facilitate recovery from the energetic costs incurred during breeding. 
 
However, they paid a price in survival. Only 67% of the high-cost birds returned the next year, compared with 83% of the control group and 90% of the fed group. 
 
The researchers say this pattern points to a hidden trade-off. To recover from a hard breeding season, kittiwakes invested more in the next migration. That strategy paid off in future reproduction but also lowered their chances of survival.  

While the survival cost of high energy demands during breeding has been documented in seabirds before, this study is the first to experimentally show that the same birds also gain more chicks the following year, through changes in their migration. ? 

¡°We use the term ‘energetic flexibility’ to describe an animal’s ability to flexibly adjust energy allocation among reproduction, survival, and migration as environmental conditions change. Our study suggests that this flexibility may be a key mechanism underlying carry-over effects, helping to explain how events in one season influence reproduction and survival in the next,¡± Shoji said. 

The findings have implications for seabirds as climate change reshapes the oceans. As prey availability shifts and conditions become less predictable, the ability to reallocate energy across seasons may decide which populations cope and which decline.?
?
The team plans to use miniature heart-rate loggers to track kittiwakes’ energy use throughout the year and identify the biological processes that drive this flexibility.?

Paper information:?

Chinatsu Nakajima, Don-Jean L¨¦andri-Breton, Marie Claire Gatt, Joan Ferrer Obiol, Diego Rubolini, Jacopo G. Cecere, Kyle H. Elliott, Shannon Whelan, Scott A. Hatch, Yasuaki Niizuma, Ken-ichiro Minato, Shigeki Wada and Akiko Shoji. 2026. Energetic flexibility as a hidden axis of life-history trade-offs: experimental evidence from a long-lived seabird, Proceedings of the Royal Society B, 293: 20253274. DOI:

Funding information:  

This work was supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (19KK0159, 20H04374, 22K21355, 23KK0116) and by the Projects of Relevant National Interest 2017 funding scheme from the Italian Ministry of University and Research (20178T2PSW). 

Expert contact:  

Akiko Shoji
Graduate School of Environmental Studies
ºÚÁϳԹÏÍø?
Email: akiko.shoji@nagoya-u.jp

Media contact:  

Merle Naidoo
International Communications Office
ºÚÁϳԹÏÍø
Email: icomm_research@t.mail.nagoya-u.ac.jp?

Top image:

Adult black-legged kittiwakes tend to their chicks at a breeding colony on Middleton Island, Alaska, where researchers experimentally raised the energy cost of flight in some birds during breeding. The study shows that birds paying higher energy costs to raise chicks migrate farther and breed more successfully the next year, but at a cost to their survival. Credit: Jumpei Okado, ºÚÁϳԹÏÍø