2945. Mammals Go Nocturnal in Bid to Avoid Humans

By Julia Jacobs, The New York Times, June 15, 2018

A coyote walking across a highway in California. Coyotes in the southern part of the state are increasingly becoming nocturnal to avoid contact with humans traversing their mountain homes, according to a new study. Photo: Justin Sullivan/Getty Images. 

Humans, it turns out, can annoy more than just one another. In fact, some animal populations are escaping their Homo sapien cohabitants by sleeping more during the day, a new study finds.

Mammals across the globe are becoming increasingly nocturnal to avoid humans’ expanding presence, according to the study, published Thursday in Science magazine. The findings show that humans’ presence alone can cause animals across continents — including coyotes, elephants and tigers — to alter their sleep schedules.

“We’re just beginning to scratch the surface on how these behavioral changes are affecting entire ecosystems,” said Kaitlyn Gaynor, an ecologist and graduate student in environmental science at the University of California, Berkeley, who led the study.

Previous research has found that mammals went from being nocturnal to being active during both day and night about 65.8 million years ago, roughly 200,000 years after most dinosaurs went extinct. “Species for millions of years have been adapting to diurnal activity, but now we’re driving them back into the night and maybe driving natural selection,” Ms. Gaynor said in an interview.

The researchers compiled data from 76 studies of 62 species living on six continents in reaching their conclusions. On average, human disruption is making these animals 1.36 times more nocturnal, according to the study.

“For example,” it says, “an animal that typically split its activity evenly between the day and night would increase its proportion of nocturnal activity to 68 percent of total activity near human disturbance.”

In California’s Santa Cruz mountains, for example, coyotes are opting to sleep more during the day in response to recreational human activities such as hiking and bicycling. As a result, coyotes are eating more nocturnal prey, whose waking hours match up more closely with theirs. Recent research such as this was used to provide data for the new study, Ms. Gaynor said. 

Thousands of miles from these night-walking coyotes, tigers living in Nepal at the base of the Himalayas are making similar lifestyle decisions. To avoid contact with humans traversing their favorite forest trails, tigers are increasingly walking the same paths during the night instead, said Neil Carter, who researched this tiger population and co-authored the new study.

This isn’t necessarily a bad thing. “The optimist in me is saying there’s a pathway for coexistence here in an otherwise challenging landscape,” said Dr. Carter, an assistant professor at Boise State University. “What we don’t know is how that might negatively affect tigers.”

Future research might strive to show how these animals’ diets, reproductive patterns and mating behavior are being affected by humans, he said.

Humans do not necessarily need to exhibit violent or blatantly destructive behavior to evoke this fear response in animals; often, our simple presence is enough, Ms. Gaynor said. 

Her own research in Mozambique showed that elephants that typically ate human-grown crops, like maize, were avoiding areas that humans inhabit during the day, but came out after sundown in full force.

Ms. Gaynor said improving technology, such as infrared cameras that can capture vivid images of animals at night and GPS collars that track their whereabouts, have helped to document the trend toward nocturnal existence.

“Working on this study reminds me that we aren’t alone on this planet,” she said. “Being mindful of the ways our activities are shaping the animals habitat will enable coexistence.”

2810. Human Activity Slashes Mammal Stomping Grounds by Up to Two-Thirds

By Roni Dengler, Science Magazine, Janaury 27, 2018

The modern world would barely be recognizable to the mammoth and bison herds of ages past. Roads subdivide large stretches of land, and clusters of buildings and people have sprung up nearly everywhere. Indeed, humans have modified the environment so much, they may have cut the distance by which mammals—large and small—roam by some two-thirds, according to a novel analysis published today. That lack of movement could upend ecosystems and increase the number of human-animal conflicts, researchers say.

“We’re moving into an era where humans have changed natural environments extensively,” says Oscar Venter, an ecologist at the University of Northern British Columbia in Prince George, Canada, who calls the new paper “very important” with significant implications. “What’s not exactly clear is what this is going to mean.”

Scientists have tried to figure out how human activity affects animals for decades. For nearly 20 years, for example, they have used GPS collars to track threatened species living in national parks, in farmlands, and near suburbs and cities. But such studies typically follow a single species or population over time, limiting how the results can be applied.

A few years ago, Marlee Tucker, a biologist at the Senckenberg Biodiversity and Climate Research Centre at Goethe University in Frankfurt, Germany, and other researchers decided to launch a much wider scale study. They wanted to compare the movements of as many mammal species as possible—from pocket mice to grizzly bears—and find out how much human actions affect those activities.

So Tucker started collecting data on the whereabouts of animals equipped with GPS collars from previous studies. She and her team assembled one of the largest data sets—more than 800 animals from 57 species—to date. They then compared the movements of those creatures with a previously published index of human activity, which included everything from the presence of roads, buildings, and nighttime lights to population density and land devoted to farming in different areas.

The team found that mammals in areas with a large human “footprint” moved half to a third as far as those in areas with a low human footprint. In areas most heavily influenced by people, the animals’ maximum roaming range averaged about 7 kilometers; for low-footprint areas, the average roaming range was 22 kilometers, Tucker and colleagues report in Science. “Such dramatic reductions in the movement of species are surprising and very important for what’s going to happen in the future,” Venter says.

That’s because movements of mammals are critical not only for the animals themselves, but for the ecosystems they inhabit. “Animals act as mobile links, linking different areas of a landscape together,” Tucker says. One of the best examples of potential ecosystem collapse is near the border of Kenya and Tanzania, in the Serengeti–Masai Mara ecosystem, says Jared Stabach, an ecologist at the Smithsonian Conservation Biology Institute in Washington, D.C. Wildebeests there carry seeds and nutrients as they traverse the landscape during their annual migration. But now that roads, agriculture, and poaching threaten their migration, that could mean those resources don’t get distributed throughout the ecosystem. The loss could trickle down to local economies that depend on tourism, Stabach says.

Humans are changing the landscape in other ways. Farmed crops provide ample food sources that encourage small and large mammals alike to take up a sedentary lifestyle. Those clusters of nonmigrating creatures in turn provide a rich breeding ground for diseases like avian flu. And the closer wildlife strays to human habitation, the greater the opportunity for human-animal conflict. “Every animal is balancing on a knife’s edge to get resources while minimizing risk,” says Grant Hopcraft, an ecologist at the University of Glasgow in the United Kingdom who was not involved in the work.

Venter would like to see a longer-term version of the study, because Tucker’s analysis examines movement over just 10 days. “That’ll tell us something about the trajectory of change as we go forward,” he says. That’s if there’s a future to go toward. Hopecraft says that built environments are increasingly widespread, and as for once-dynamic ecosystems, “We’re essentially wrapping them in plastic shrink wrap and hoping they’re going to survive.”

2095. Thanksgiving in California: The Ban on Recreational and Commercial Bobcat Trapping Begins

By Endangered Earth, November 25, 2015

A juvenile bobcat

Here's something to be thankful for this week: On Friday, three days before bobcat trapping season had been scheduled to begin, a California state regulation banning both recreational and commercial trapping of these beautiful cats went into effect. The Center for Biological Diversity and local allies worked hard to bring the ban, voted into effect in August, into being.

From now on it's illegal to trap any bobcat, or sell or export bobcat fur or parts, anywhere in the state. Any holder of a trapping license who traps a bobcat by accident must immediately release it to the wild unharmed.

"This is a great moment," said Center Senior Counsel Brendan Cummings, who worked for the ban. "Fifteen years into the 21st century, state wildlife management has finally entered the 20th century."

Thanks to all of you who chipped in for this victory. Read more in the Los Angeles Times.

1641. From Cat to Kitties

By David Grimm, Science Magazine, November 10, 2014

The house cat evolved from Near Eastern wild cat pictured above

Place a housecat next to its direct ancestor, the Near Eastern wildcat, and it may take you a minute to spot the difference. They’re about the same size and shape, and, well, they both look like cats. But the wildcat is fierce and feral, whereas the housecat, thanks to nearly 10,000 years of domestication, is tame and adaptable enough to have become the world’s most popular pet. Now scientists have begun to pinpoint the genetic changes that drove this remarkable transformation. The findings, based on the first high-quality sequence of the cat genome, could shed light on how other creatures, even humans, become tame.

“This is the closest thing to a smoking gun we’ve ever had,” says Greger Larson, an evolutionary biologist at the University of Oxford in the United Kingdom who has studied the domestication of pigs, dogs, and other animals. “We’re much closer to understanding the nitty-gritty of domestication than we were a decade ago.”

Cats first entered human society about 9500 years ago, not long after people first took up farming in the Middle East. Drawn to rodents that had invaded grain stores, wildcats slunk out of the deserts and into villages. There, many scientists suspect, they mostly domesticated themselves, with the friendliest ones able to take advantage of human table scraps and protection. Over thousands of years, cats shrank slightly in size, acquired a panoply of coat colors and patterns, and (largely) shed the antisocial tendencies of their past. Domestic animals from cows to dogs have undergone similar transformations, yet scientists know relatively little about the genes involved.

Researchers led by Michael Montague, a postdoc at the Washington University School of Medicine in St. Louis, have now pinpointed some of them. The scientists started with the genome of a domestic cat—a female Abyssinian—that had been published in draft form in 2007, then filled in missing sequences and identified genes. They compared the resulting genome with those of cows, tigers, dogs, and humans.

The analysis, published online this week in the Proceedings of the National Academy of Sciences, revealed 281 genes that show signs of rapid or numerous genetic changes—a hallmark of recent selection—in domestic cats. Some appear to be involved in hearing and vision, the senses that felines rely on most. Others play a role in fat metabolism and are likely an adaptation to cats’ highly carnivorous lifestyle.

But the most intriguing findings came when the team sequenced the genomes of 22 domestic cats—representing a wide variety of breeds and locations— and compared them with the genomes of two Near Eastern and two European wildcats. The researchers uncovered at least 13 genes that changed as cats morphed from feral to friendly. Some of these, based on previous studies of knockout mice, seem to play a role in cognition and behavior, including fear responses and the ability to learn new behaviors when given food rewards. “That jibes with what we know about the domestication of cats,” Montague says, “because they would have needed to become less fearful of new locations and individuals, and the promise of food would have kept them sticking around.”

“This is my favorite part of the paper,” says Kerstin Lindblad-Toh, a leading comparative genomicist at Uppsala University in Sweden who was not involved in the work. She notes that a few of the genes the team identified code for glutamate receptors, which play a key role in learning and memory and may have been selected in humans as well. “We’re hitting on genes that allow our brains to develop and make us interact socially.”

The team also found five genes in domestic cats that influence the migration of neural crest cells, stem cells in the developing embryo that affect everything from skull shape to coat color. This supports a recent proposal that such cells may be the master control switches of domestication, explaining why domestic animals share common traits, such as smaller brains and certain pigmentation patterns—a mystery first noted by Charles Darwin.

If cats sport genetic changes akin to those of other domestic animals, why are they still a bit wilder than our other favorite domesticate, the dog? Co-author William Murphy, a geneticist at Texas A&M University, College Station, says the cat genome appears to have undergone less intense and more recent evolutionary pressure than that of dogs; that’s not surprising, considering that dogs may have lived with us for up to 30,000 years. “Cats were not selected for a purpose like dogs and other domesticates,” Murphy speculates. “They just hung out, and humans tolerated them.”

Still, Larson doesn’t think it’s fair to call cats “semi-domesticated,” as the authors do in their paper. “I’ve got two cats at home, and they’re as domesticated as any animal on earth,” he says. “There are homes where cats just sit on the couch, ignoring the dogs and primates that should be a major threat to them. That’s asking a lot of a wild carnivore.”

1637. Why Some Mammal Species Kill Their Infants?

By Carl Zimmer, The New York Times, November 13, 2014

In the early 1970s, Sarah Blaffer Hrdy, then a graduate student at Harvard, traveled to India to study Hanuman langurs, monkeys that live in troops, each made up of several females and a male.

From time to time, Dr. Hrdy observed a male invade a troop, driving off the patriarch. And sometimes the new male performed a particularly disturbing act of violence. He attacked the troop’s infants.

There had been earlier reports of infanticide by adult male mammals, but scientists mostly dismissed the behavior as an unimportant pathology. But in 1974, Dr. Hrdy made a provocative counter proposal: infanticide, she said, is the product of mammalian evolution. By killing off babies of other fathers, a male improves his chances of having more of his own offspring.

Dr. Hrdy went on to become a professor at the University of California, Davis, and over the years she broadened her analysis, arguing that infanticide might well be a common feature of mammalian life. She spurred generations of scientists to document the behavior in hundreds of species.

“She’s the goddess of all this stuff,” said Kit Opie, a primatologist at University College London.

Forty years after Dr. Hrdy’s initial proposal, two evolutionary biologists at the University of Cambridge have surveyed the evolution of infanticide across all mammals. In a paper published Thursday in Science, the scientists concluded that only certain conditions favor the evolution of infanticide — the conditions that Dr. Hrdy had originally proposed.

“My main comment is, ‘Well done,'” said Dr. Hrdy. She said the study was particularly noteworthy for its scope, ranging from opossum to lions.

The authors of the new study, Dieter Lukas and Elise Huchard, started by plowing through the scientific literature, looking for evidence of infanticide in a variety of mammalian species. The researchers ended up with data on 260 species, and in 119 of them — over 45 percent — males had been observed killing unrelated young animals.

Dr. Lukas and Dr. Huchard then looked at how infanticide might have evolved over the past 160 million years of mammal evolution. “When we started, we weren’t sure if infanticide was present in some ancestral mammal and is just more pronounced in some species and is lost in other species,” said Dr. Lukas. “Or maybe it just evolved in those species where the conditions were right.”

Their research supports the second scenario. The common ancestor of living mammals did not practice infanticide: The behavior evolved later and independently in a number of separate animal lineages.

Dr. Lukas and Dr. Huchard found that the species that evolved infanticide had a few things in common. For instance, the females tended to give birth year-round, rather than at just one time of the year. Another key factor was that males and females lived in groups where females greatly outnumber males.

The scientists concluded that conditions such as these fostered the evolution of infanticide. If only a few males get to mate with females, there will be a lot of other males facing the prospect of dying childless. Natural selection will favor males that can take over groups of females.

But these males are pressed for time. It won’t be too long before another male threatens them with exile. Meanwhile, many females will be busy nursing infants. Killing the offspring of other males can free up females for reproduction and widen the window of opportunity for new males, leading to more offspring for them.

The researchers also noted that infanticide generally did not evolve in species where females only give birth once a year. “There’s no sense for a male to kill the offspring in the previous year, because he has to wait anyway,” said Dr. Lukas.

Dr. Hrdy and other early infanticide researchers not only investigated how infanticide might have evolved. They also suggested that mothers and fathers had evolved defenses against infanticidal males.

Dr. Lukas and Dr. Huchard found support for this idea, too. In species in which infanticide appeared, females gradually mate with more and more males. This behavior may protect infants by introducing uncertainty: Males might be more reluctant to kill infants if one of them could be his own.

“In effect, whenever promiscuity is high enough, it does not pay for males to commit infanticide,” said Carel P. Van Schaik, a primatologist at the University of Zurich. “This new study beautifully confirms the major role of sexual behavior.”

Despite its sweep, , the new study doesn’t settle every debate over infanticide. Dr. Van Schaik, for example, suspects that the true number of infanticidal species is higher. In some of them, defenses against the practice have become so effective that infanticide has become rare, and therefore hard for scientists to observe.

The new study also clashes with earlier work finding that infanticide altered the social structure of some species. Last year, for example, Dr. Opie and his colleagues reported that monogamy — in which one male and one female lived together — has evolved in primates as a defense against infanticide.

In their new study, Dr. Lukas and Dr. Huchard found no such pattern. Dr. Opie believes that is partly because they didn’t take into account the full diversity of how mammals mate.

“What we’re saying is that infanticide is driving monogamy, and we don’t think anything they’ve shown in this paper contradicts that,” said Dr. Opie.

Among the mammal species that Dr. Lukas and Dr. Huchard didn’t include in their study was our own. Dr. Lukas said the cultural diversity of humans means it is hard to make blanket statements about them. “For many social behaviors, it’s very difficult to define a human universal,” said Dr. Lukas.

That’s not to say that adults never harm — or even kill — children. But Dr. Hrdy argued that the infanticide she documented in langurs — in which males stalked babies for days —was fundamentally different from what happens in our own species.

“A male would have to pull out a butcher knife and stab the baby, but that’s not what you’re seeing,” said Dr. Hrdy. “I don’t think langur infanticide tells us much. I think it’s a very different phenomenon.”