Changes to cougar diets and behaviors reduce their competition with wolves in Yellowstone

Researcher Wesley Binder climbs a tree to reach a cougar to be collared with a GPS device.
Photo Credit: Jake Frank, National Park Service

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Interactions between Yellowstone wolves and cougars are driven by wolves usurping cougar kills, prompting cougars to adapt by shifting their diet to smaller prey that can be consumed quickly and utilizing escape terrain to avoid fatal encounters.
• Methodology: Researchers analyzed nine years of GPS telemetry data from collared animals and conducted field investigations of 3,929 potential kill sites to train machine learning models capable of predicting interaction drivers and kill site locations.
• Key Data: Interactions were highly asymmetric, with 42% occurring at cougar kill sites versus only one recorded event at a wolf kill site; simultaneously, cougar predation on elk declined from 80% to 52% while deer consumption increased from 15% to 42% between study periods.
• Significance: The study establishes that the coexistence of competing apex predators relies heavily on prey diversity and the availability of complex landscape features, such as climbable trees or cliffs, rather than simply the overall abundance of prey.
• Future Application: These findings will inform management and recovery efforts for overlapping carnivore populations in the Western United States by highlighting the necessity of preserving diverse prey bases and habitat structures to reduce interspecific competition.
• Branch of Science: Ecology and Wildlife Biology

Aging Zoo Animals Threaten Long-Term Species Conservation Goals of Modern Zoos

The analysis of Meireles and colleagues shows that reproduction, as shown here in the endangered Grévy's zebra (Equus grevyi), is on the decrease across zoo mammal populations
Photo Credit: Tim Benz/Zoo Zürich

Scientific Frontline: "At a Glance" Summary

• Main Discovery: A comprehensive analysis reveals that zoo mammal populations in North America and Europe are undergoing a significant demographic shift toward aging structures, transitioning from resilient "pyramid" shapes to fragile "diamond" shapes, which directly threatens their long-term viability and the ex-situ conservation mandates of modern zoos.
• Methodology: Researchers analyzed demographic data from 774 mammal populations across European (413) and North American (361) zoos between 1970 and 2023 using the global Species360 database, utilizing a novel automated classification method developed by Goethe University Frankfurt to compare population pyramid shapes and reproductive trends over time.
• Key Data: The study found that 63% of European and 40% of North American populations currently exhibit aging trends, while the proportion of actively reproducing females has plummeted by 68% in Europe and 49% in North America; furthermore, 14% of North American and 3% of European populations recorded in 1970 have since vanished entirely.
• Significance: This "graying" of zoo populations creates a demographic bottleneck where finite space is occupied by non-breeding geriatric individuals, drastically reducing the birth of new generations and compromising the ability of zoos to function as genetic reservoirs or "arks" capable of restocking wild populations.
• Future Application: To reverse these trends, zoo management strategies must likely pivot from prioritizing individual animal longevity to ensuring population-level sustainability, which may necessitate controversial interventions such as increased breeding combined with the humane culling of surplus or post-reproductive individuals to restore healthy demographic structures.
• Branch of Science: Conservation Biology and Population Demography
• Additional Detail: The demographic shift is largely attributed to the success of modern veterinary care extending individual lifespans, which, when combined with space limitations and reproductive restrictions (contraception/separation), has inadvertently stalled the generational turnover required for sustainable populations.

Meet the marten: Oregon State research provides updated look at rare, adorable carnivore

Humboldt marten.
Photo Credit: Ben Wymer, A Woods Walk Photography

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Genetic analysis confirmed the presence of 46 individual coastal martens within a 150-square-mile Northern California study area, establishing their habitation of both high-elevation forested ridgetops and lower-elevation riparian ravines.
• Methodology: Researchers deployed non-invasive survey tools, including 285 PVC pipe hair snares for DNA collection and 135 remote cameras, across ancestral Yurok and Karuk lands to accurately map distribution and demography.
• Key Data: The study identified 28 males and 18 females, revealing a specific preference for forest stands exhibiting greater than 50% canopy cover and complex structures like large-diameter trees, snags, and hollow logs.
• Significance: This research provides essential baseline estimates for the Humboldt marten, a species listed as threatened under the Endangered Species Act that was considered extinct until its rediscovery in 1996.
• Future Application: Findings will directly guide land management decisions for the Yurok Tribe and U.S. Forest Service, helping to prioritize the conservation of old-growth forest characteristics against threats like wildfire and climate change.
• Branch of Science: Wildlife Ecology and Conservation Biology
• Additional Detail: The study highlights the resilience of the species in a mixed-use landscape involving timber harvesting and cattle grazing, emphasizing the need to mitigate modern risks such as rodenticides and vehicle strikes.

Hot spring bathing doesn't just keep snow monkeys warm

Video Credit: Abdullah Langgeng

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Hot spring bathing behaviors in Japanese macaques actively reshape the host "holobiont," specifically modifying lice distribution and gut microbiota composition beyond simple thermoregulation or stress relief.
• Methodology: Researchers conducted a comparative study over two winters at Jigokudani Snow Monkey Park, utilizing behavioral observations, ectoparasite monitoring, and gut microbiome sequencing to analyze differences between female macaques that bathed regularly and those that did not.
• Key Data: Bathers exhibited distinct lice distribution patterns (suggesting disruption of activity or egg placement) and a lower abundance of specific bacterial genera, yet showed no increase in intestinal parasite infection rates or intensity despite sharing communal water sources.
• Significance: The study provides empirical evidence that voluntary animal behaviors act as direct drivers of host-parasite and host-microbe interactions, challenging the assumption that shared water sources in the wild necessarily amplify disease transmission risks.
• Future Application: Insights from this research will aid in modeling the co-evolution of behavior and health in social animals and offer comparative frameworks for understanding how cultural practices, such as communal bathing, influence microbial exposure in primates.
• Branch of Science: Primatology, Ethology, and Microbial Ecology
• Additional Detail: The findings underscore the concept of the holobiont—an integrated system of the host and its symbiotic organisms—as a dynamic entity modulated by behavioral choices rather than solely by environmental constraints.

Zoology: In-Depth Description

Image Credit: Scientific Frontline / AI generated (Gemini)

Zoology is the branch of biology dedicated to the scientific study of the animal kingdom, encompassing the structure, embryology, evolution, classification, habits, and distribution of all living and extinct animals. As a discipline, it seeks to understand how animals interact with their ecosystems, how they function physiologically, and how they have adapted to diverse environments over millions of years.

Bear teeth break free – Researchers discover the origin of unusual bear dentition

Lower jaw of a polar bear
The polar bear has a second molar that is only slightly larger than the first. Although the polar bear is a carnivore, it is descended from the omnivorous brown bear. 
Photo Credit: © Katja Henßel, SNSB

Mammalian teeth show an astonishing diversity that has developed over 225 million years. One approach to describing the development of mammalian teeth is the so-called “Inhibitory Cascade Model”, short ICM. The ICM describes the growth pattern of molars in the lower jaw. According to the model, the following applies to many mammals: The front molars in the lower jaw influence the growth of all the teeth behind them. 

Certain molecules inhibit or activate tooth growth in the animal's dentition according to the same pattern. Which molars become small or large depends on the size of the first molar, which depends on the animal's diet. In carnivorous mammals, the first molar is usually larger than the third. In herbivores, it is the other way around: the first molar is small, while the third is large. 

An electric discovery: Pigeons detect magnetic fields through their inner ear

Photo Credit: Nancy Hughes

In 1882, the French Naturalist Camille Viguier was amongst the first to propose the existence of a magnetic sense. His speculation proved correct; many animals – from bats to migratory birds and sea turtles use the Earth’s magnetic field to navigate. Yet despite decades of research, scientists still know surprisingly little about the magnetic sense. How do animals detect magnetic fields? Which brain circuits process the information? And where in the body is this sensory system located? 

Viguier audaciously proposed that magnetic sensing might occur in the inner ear relying on the generation of small electric currents. This idea was ignored and then forgotten; a historical musing lost with the passage of time. Now more than a century later it has been resurrected by neuroscientists at LMU in a paper published in Science. A team led by Professor David Keays took an unbiased approach to studying pigeon brains exposed to magnetic fields. 

A Microbial Blueprint for Climate-Smart Cows

Matthias Hess, with the UC Davis Department of Animal Science, and researchers at UC Berkeley, have identified which microbes in a cow's gut could help reduce methane. It brings them a step closer to engineering gut microbes to create more climate-friendly cows.
Photo Credit: Gregory Urquiaga / UC Davis

Each year, a single cow can belch about 200 pounds of methane. The powerful greenhouse gas is 27 times more potent at trapping heat in the atmosphere than carbon dioxide. For decades, scientists and farmers have tried to find ways to reduce methane without stunting the animal’s growth or productivity. 

Recent research at University of California, Davis, has shown that feeding cows red seaweed can dramatically cut the amount of methane that is produced and released into the environment. Until now, however, scientists did not fully understand how red seaweed changes the interactions among the thousands of microbes in the cow’s gut, or rumen. 

Three new toad species skip the tadpole phase and give birth to live toadlets

One of the newly described toad species, Nectophrynoides luhomeroensis.
Photo credit: John Lyarkurwa

An international team of researchers have identified three new species of enchanting, pustular, tree-dwelling toads from Africa. Their solution for having offspring away from water? Skipping the tadpole phase altogether, and giving birth to live toadlets. The study is published today in the open access scientific journal Vertebrate Zoology.

Most textbooks will tell you only one story of frog reproduction: Eggs to tadpoles to froglets to adults. But for three newly discovered species found in Tanzania this is not the case. The three new species of frogs belong to an unusual group of African toads in the genus Nectophrynoides — commonly called “Tree Toads.”

Instead of laying eggs that hatch into tadpoles, the female Tree Toads carry their offspring inside their bodies and give birth to fully formed, tiny toads. This makes them among the very few amphibians in the world capable of internal fertilization and true live birth.

Carpenter Ants: Better Safe than Sorry

Camponotus maculatus
Photo Credit: April Nobile
(CC BY-SA 4.0)

Carpenter ants are not squeamish when it comes to caring for the wounded. To minimize the risk of infection, the insects immediately amputate injured legs – thereby more than doubling their survival rate.

As with humans, wound care plays an important role in the animal kingdom. Many mammals lick their wounds, some primates use antiseptic plants, and some ants even produce their own antimicrobial substances to treat infections. 

The latter was demonstrated by biologist Dr. Erik Frank, a researcher at Julius-Maximilians-Universität Würzburg (JMU), in the African Matabele Ant. In a new study, now published in the journal Proceedings of the Royal Society B, he takes a closer look at an ant species that uses a less refined but nevertheless effective approach: amputation.   

Erik Frank heads a junior research group in Würzburg funded by the Emmy Noether Programme of the German Research Foundation (DFG) at the Chair of Animal Ecology and Tropical Biology (Zoology III). 

African Wildlife Poop Sheds Light on What Shapes the Gut Ecosystem

Photo Credit: James C. Beasley

A study of elephants, giraffes and other wildlife in Namibia’s Etosha National Park underscores the ways in which the environment, biological sex, and anatomical distinctions can drive variation in the gut microbiomes across plant-eating species. Because the gut microbiome plays a critical role in animal health, the work can be used to inform conservation efforts.

“This study is valuable because Etosha gave us the opportunity to sample such a large number of species under different environmental conditions,” says Erin McKenney, co-author of a paper on the work and an assistant professor of applied ecology at North Carolina State University. “That gives us meaningful insight into the role the environment plays in shaping the gut microbiome of herbivores.

“Unfortunately, this study may also be important for a second reason,” McKenney says. “Etosha is experiencing devastating wildfires affecting a huge section of the park. Because our samples were taken before the wildfires, these findings could inform recovery efforts by helping us understand how species’ microbiomes are adjusting to changes in diet that stem from the fire’s impact on the landscape.”

Major new study discovers diet and migratory behavior shape neophobia

Flamingos were one of the species to exhibit the highest neophobia.
Photo Credit: Jeffrey Hamilton

The largest-ever study on neophobia, or fear of novelty, has discovered the key reasons why some bird species are more fearful of new things than others.

Published in the journal PLOS Biology, the global multi-species study was led by the University of Exeter’s Dr Rachael Miller while at Anglia Ruskin University (ARU), and the University of Cambridge – with ARU funding the publication of the research – alongside a core leadership team from the ManyBirds Project.

Neophobia plays a crucial role in how animals balance risk and opportunity. While caution can protect individuals from potential threats, it can also limit their ability to adapt to new nesting sites, foods or changes in the environment.

The research involved 129 collaborators from 82 institutions. Testing, and other associated research tasks, took place in 24 countries across six continents – including lab, field and zoo sites – and investigated why some birds are more cautious than others when encountering unfamiliar objects when feeding.

Male crickets bulk up, females invest in reproductive organs

The study was done with the Gryllus vocalis species of field crickets found throughout the Southwest United States.
Photo Credit: Susan Gershman

A lab study in crickets has revealed sex differences in how the insects direct their nutritional resources to increase chances of generating offspring, finding that females prepare for producing eggs while males prioritize growing bigger bodies and banking extra energy. 

In insects that mated, the females’ investment in reproductive organs was even greater, but minimal change was seen in males – a sign that males’ reproductive success is related more strongly to winning the competition for mates, the research suggests. 

Ensuring survival while distributing finite resources is a trade-off faced by all living creatures, said first author Madison Von Deylen, a PhD candidate in the Department of Evolution, Ecology and Organismal Biology at The Ohio State University. 

“Any organism is going to face these trade-offs between allocating limited resources: Should I invest in growth? Should I build up fat stores? Or should I transition energy into some kind of reproductive output?” Von Deylen said.  

Hostile hoots make robins eat less at night

At night, the little robin is extra vigilant
Photo Credit: Johan Nilsson

The sound of tawny owls makes young European robins eat less during their southward migration. A new study from Lund University in Sweden shows how the threat from nocturnal predators affects the birds’ behaviour – and by extension their survival.

When young robins embark on their first southward migration in the autumn, they make regular stops along the way to rest and replenish their energy reserves. However, each stop entails a risk – predators may be lurking nearby. 

In an article in the Journal of Animal Ecology, a research team has established that migrating birds are not only aware of threats around them, but also adapt their behaviour based on which predator calls they hear.

Woodrats’ dietary choices driven by constraints

A woodrat munches on a juniper berry.
Photo Credit: Sara Weinstein/USU

It’s not easy eating green, as most plants have chemical defenses to deter would-be grazers. Getting enough to eat, while minimizing exposure to toxins, is a persistent challenge that shapes an herbivore’s foraging choices. Do they boost their survival by eating a bit of everything, bypass biological booby traps by specializing on one plant or adapt their strategy as environmental conditions change?

The diversity of an animal’s diet—known as dietary niche breadth—is critical to a species’ resilience, yet it remains poorly understood in mammalian herbivores. In a new study, researchers report findings from an eight-year, large-scale survey exploring the dietary choices of a model herbivore, the woodrat (genus: Neotoma). By analyzing plant DNA in the rodents’ droppings, the scientists compared dietary breadth between individuals, within populations and across species of woodrats throughout North America.

Woodrats exhibited a wide spectrum of diet diversity that included both generalists and specialists. Species-level specialists stuck to narrow food niches, with little difference between individual diets. In contrast, generalist populations contained individuals with more varied diets. Even these individuals appeared to forage on a consistent subset of plants, which likely helps them to manage the risks of consuming potentially poisonous food.

Women of Science: A Legacy of Achievement

Future generations to pursue their passions and break down barriers in the pursuit of knowledge.
Image Credit: Scientific Frontline stock image

Throughout history, women have made groundbreaking contributions to science, despite facing significant societal barriers and a lack of recognition. Their relentless pursuit of knowledge and innovation has shaped our understanding of the world and paved the way for future generations of scientists. This article celebrates the achievements of some of these remarkable women, highlighting their struggles and the impact of their work.

The women featured in this article, along with countless others throughout history, have made invaluable contributions to the advancement of science. Their achievements, often accomplished in the face of adversity and societal barriers, have shaped our understanding of the world and paved the way for future generations of scientists. These women demonstrate the power of perseverance, the importance of challenging established norms, and the profound impact that individual dedication can have on scientific progress. By recognizing and celebrating their legacies, we not only honor their contributions but also inspire future generations to pursue their passions and break down barriers in the pursuit of knowledge.

Life cycles of some insects adapt well to a changing climate. Others, not so much.

A grasshopper, Melanoplus boulderensis, typical of the Colorado Rocky Mountains.
Photo Credit: ©Thomas Naef, 2022

As insect populations decrease worldwide in what some have called an “insect apocalypse,” biologists are desperate to determine how the six-legged creatures are responding to a warming world and to predict the long-term winners and losers.

A new study of Colorado grasshoppers shows that, while the answers are complicated, biologists have much of the knowledge they need to make these predictions and prepare for the consequences.

The findings, published in the journal PLOS Biology, come thanks to the serendipitous discovery of 13,000 grasshoppers collected from the same Colorado mountain site between 1958 and 1960 by a biologist at the University of Colorado Boulder (CU Boulder). After that scientist’s untimely death in 1973, the collection was rescued by his son and donated to the CU Museum, where it languished until 2005, when César Nufio, then a postdoctoral fellow, rediscovered it. Nufio set about curating the collection and initiated a resurvey of the same sites to collect more grasshoppers.

Blood-powered toes give salamanders an arboreal edge

Wandering salamanders are known for gliding high through the canopies of coastal redwood forests, but how the small amphibians stick their landing and take-off with ease remains something of a mystery.

A new study in the Journal of Morphology reveals the answer may have a lot to do with a surprising mechanism: blood-powered toes. The Washington State University-led research team discovered that wandering salamanders (Aneides vagrans) can rapidly fill, trap, and drain the blood in their toe tips to optimize attachment, detachment and general locomotion through their arboreal environment.

The research not only uncovers a previously unknown physiological mechanism in salamanders but also has implications for bioinspired design. Insights into salamander toe mechanics could ultimately inform the development of adhesives, prosthetics, and even robotic appendages.

“Gecko-inspired adhesives already allow surfaces to be reused without losing stickiness,” said Christian Brown, lead author of the study and an integrative physiology and neuroscience postdoctoral researcher at WSU. “Understanding salamander toes could lead to similar breakthroughs in attachment technologies.”

How mites have survived for millions of years

oribatid mite Platynothrus peltifer
Image Credit: Gemini (AI)

An international research team has discovered various mechanisms in asexual mites that generate genetic diversity and thus ensure survival

In collaboration with colleagues from international partner institutions, researchers at the University of Cologne have investigated the asexual reproduction of oribatid mites using genome sequencing techniques. They show that the key to evolution without sex in oribatid mites may lie in the independent evolution of their two chromosome copies – a phenomenon known as the ‘Meselson effect’. The research team identified various mechanisms that may contribute to the genetic diversity of the chromosome sets, potentially enabling the long-term persistence of the mite.

Like humans, oribatid mites possess two sets of chromosomes. However, the asexual oribatid mite Platynothrus peltifer reproduces parthenogenetically: Mothers produce daughters from unfertilized eggs, resulting in a population consisting entirely of females. Using single-individual sequencing, the researchers analysed the accumulated differences between the chromosome copies for the first time and evaluated their significance for the mite’s survival. The study titled ‘Chromosome-scale genome dynamics reveal signatures of independent haplotype evolution in the ancient asexual mite Platynothrus peltifer’, funded by the German Research Foundation (DFG), was published in Science Advances.

Peeing with your peers

 

Male chimps socializing
Photo Credit: Kyoto University, Kumamoto Sanctuary

In Italy, it has been said, there is a proverb for everything.

Chi non piscia in compagnia o è un ladro o è una spia -- "Whoever doesn't pee in the company of others is either a thief or a spy" -- goes one such saying, describing a communal act that in Japanese is known as tsuré-shon.

Social urination can be found represented in artwork across the centuries and around the world, and even today continues to be represented in cultural tropes. Now, researchers in Japan -- observing chimpanzees -- are suggesting that this phenomenon has evolutionary roots even deeper than previously expected.

Despite decades of research into other contagious behaviors such as yawning, contagious urination has never been studied scientifically in any species. To tackle this, a team at Kyoto University conducted 604 hours of direct observation at the University's Kumamoto Sanctuary, documenting 1,328 urination events. The researchers analyzed whether these were aligned in time, triggered by nearby individuals, or influenced by social relationships.