American wildfires too big for fire-loving woodpeckers

This August 2013 video from the USA says about itself:

Black-backed woodpeckers thrive in recently burned forests. The Forest Service and the Institute for Bird Populations are learning more about these birds and their habitat. This effort will inform future restoration work on the national forests in California.

From the American Ornithological Society Publications Office in the USA:

‘Mega-fires’ may be too extreme even for a bird that loves fire

August 6, 2019

Fire is a natural part of western forests, but the changing nature of fire in many parts of North America may pose challenges for birds. One bird in particular, the Black-backed Woodpecker, specializes in using recently-burned forests in western North America, but like humans looking for a new family home, it’s picky about exactly where it settles. New research published in The Condor: Ornithological Applications suggests that these birds actually prefer to nest near the edges of burned patches — and these edges are getting harder to find as wildfires have become bigger and more severe.

Andrew Stillman, a Ph.D. candidate at the University of Connecticut, along with colleagues from The Institute for Bird Populations and the U.S. Forest Service, looked at nest site selection and nest success of Black-backed Woodpeckers in burned forests of northern California. Over a period of eight years, the researchers located and monitored more than one hundred nests while measuring nest site characteristics across multiple spatial scales. The birds in the study strongly preferred to nest in severely burned stands that had lots of dead trees. But the birds chose to place their nests near the edges of these high-severity burned patches, typically within 500 meters of a patch with live trees.

“We didn’t expect to find these woodpeckers nesting so close to edges,” says Stillman. Previous studies had shown that woodpecker nests closer to living forest patches were more likely to be predated by animals such as squirrels. However, another recent study by Stillman and others showed that Black-backed Woodpecker fledglings often move into living patches with good cover quickly after leaving their nest. By placing nests closer to edges, adults may be providing their offspring easier access to this “nursery” habitat.

Stillman notes that “pyrodiversity”, or a diversity in the age, size and severity of burned patches, appears to be important for this post-fire specialist woodpecker because it provides more edges between different burn severities. But climate change is fostering larger, more homogeneous fires with reduced pyrodiversity.

“The thing about pyrodiversity is that we expect it to decrease,” says Dr. Morgan Tingley of the University of Connecticut and co-author of the paper. “Every year we see more ‘mega-fires,’ and these fires are quite homogenous in their structure, leading to low pyrodiversity. So even though the future is expected to hold more fire in western forests, the outlook may not even be good for fire-loving species.”

Stillman anticipates that understanding the importance of habitat edges to Black-backed Woodpeckers, as well as other findings of this study, will assist forest managers. “We hope that these results provide some of the missing information necessary to balance post-fire logging activities with the habitat needs of woodpeckers,” he says. Dr. Rodney Siegel, Executive Director of The Institute for Bird Populations and a co-author of the study, agrees. “A central goal of our multi-year partnership with the Forest Service is to better understand the specific habitat needs of Black-backed Woodpeckers and other species that use burned forests. This information allows forest managers to design management activities that are more compatible with the needs of wildlife.”


Racist mass murder in Gilroy, USA

This 30 July 2019 video from the USA is called A quick look at the gunman in deadly Gilroy Garlic Festival shooting.

By Patrick Martin in the USA:

The fascist attack in Gilroy and the US epidemic of mass shootings

31 July 2019

The killing of three people at the Garlic Festival in Gilroy, California captured headlines across America, but the corporate media has sought to suppress or downplay its most important aspect: its politically motivated character.

Nineteen-year-old Santino William Legan opened fire with an AK-47 assault rifle inside the festival late Sunday afternoon. He killed three people—a six-year-old boy, a 13-year-old girl, and a 25-year-old man—and wounded at least 15 others before being shot to death by local police.

The three people he killed were Hispanic or African-American. This was apparently not an accident. Legan’s internet postings indicate he was motivated by racist and white supremacist views. The most important indication was a piece of text urging, “Read Might is Right by Ragnar Redbeard”, followed by a complaint about “hordes of mestizos” (mixed-race people) allegedly crowding into towns in the Gilroy area.

The book Legan praises is Might is Right or The Survival of the Fittest, a social Darwinist, white supremacist screed first published in 1890, inspired by, among others, the reactionary German philosopher Friedrich Nietzsche. One passage in the book denounces the [18th century USA] Declaration of Independence for the “degrading, self-evident lie” that “all men are created equal.” This is followed by imprecations against blacks, Asians, Jews and the poor, as well as those who live in “noxious” urban centers like London, Liverpool, New York, Chicago and New Orleans—language whose modern equivalent is Donald Trump’s denunciations of “rat-infested,” crime-plagued Baltimore.

Despite this clear evidence of Legan’s political sympathies, local police and the national media claimed that the motive for his attack was a mystery, and that it was just one more “senseless killing” of the type which has become commonplace in the United States over the past three decades.

Not a single prominent media pundit or newspaper columnist made the obvious connection between Legan’s mentality and the fascistic hatred of immigrants and minorities promoted by the president of the United States, using mass rallies, comments to the media and tweets directed to a Twitter audience of more than 50 million.

The media cover-up only gained a certain plausibility because the Gilroy attack was one of ten instances of mass shooting across the United States over the past weekend. The casualty toll showed 15 deaths and 52 wounded.

The slaughter continued after the beginning of the work week. Tuesday morning at a Walmart in Southaven, Mississippi, a suburb of Memphis, Tennessee, a gunman shot two Walmart workers to death and wounded a policeman before he was himself shot and arrested.

The media response to these tragedies has been twofold: using them to disguise the specifically political aspects of the Gilroy, California attacks; and holding them up as proof of the need for stepped up repressive measures, including not only the usual liberal calls to restrict gun ownership, but stepped-up police powers as well.

Particularly noteworthy was an editorial in the Washington Post, owned by billionaire Jeff Bezos, the richest man in the world, which made no mention of the fascistic beliefs of the gunman and declared that the Gilroy shootings were “an indictment of our gun laws”. The editorial went on to note the heavy security presence of police during the Gilroy attack, and their quick response, shooting Legan to death one minute after he opened fire. The implication was clear: quicker and more massive police repression was in order.

In the two decades since the Columbine massacre made “mass shootings” a recognized category of events in the United States, the World Socialist Web Site has sought to develop a critical understanding of what is typically dismissed as “senseless violence” in America.

As we noted in a recent commentary, the two decades since Columbine coincide with the decomposition of American society under the impact of mounting social inequality and endless imperialist war:

It has also been two decades, more or less, since the declaration of the “war on terror” and the invasions of Afghanistan and later Iraq, two decades since the hijacking of a national election and the repudiation of any concern by the American bourgeoisie for democratic norms, two decades of mounting social inequality and two decades of unrelenting attacks on workers’ conditions of life…

American capitalist society is disintegrating. Mad, individual anti-social acts such as the one that occurred at Columbine will not be halted by the pious wishes, much less the indifference, of the powers that be.

There has been a change in the general category of “mass shootings,” which have increasingly acquired a political character.

Of course, the event that to a certain extent triggered the wave of mass killings, the Columbine murders, had an element of this. It was planned for Hitler’s birthday and the anniversary of the Oklahoma City bombings. Now, however, such politically-motivated massacres happen with regularity, including the attack by a fascist gunman against a synagogue in Poway, California in April of this year and the Tree of Life synagogue massacre in Pittsburgh in October 2018.

And as the example of the Gilroy, California attack demonstrates, far from “pious wishes” about an end to such violence, the current American government is deliberately inciting such atrocities. President Trump is pursuing a definite political strategy, politically facilitated by the Democrats, of stoking violence and creating the conditions for ever more authoritarian measures.

The capitalist system as a whole is responsible. The bitter disappointment in Obama, the fascist incitement of Trump, in combination with the economic hardships and endless war, have encouraged or produced a new phenomenon, the openly right-wing mass shooter.

The author also recommends:

Three dead in Gilroy, California festival shooting: Gunman motivated by white supremacist ideology
[30 July 2019]

Fascist gunman attacks California synagogue
[29 April 2019]

White supremacist massacre in California, USA

This 30 July 2019 video from the USA is called Gilroy festival gunman’s ‘white supremacist‘ Instagram post hours before shooting.

By Kate Randall in the USA:

Three dead in Gilroy, California festival shooting

Gunman motivated by white supremacist ideology

30 July 2019

Early Sunday evening, the annual Garlic Festival in Gilroy, California became the scene of the latest mass shooting in the US. Just after 5:30 p.m., festivalgoers and vendors heard popping sounds, which some initially mistook for firecrackers. Soon they realized that the sounds came from an assault rifle being fired indiscriminately.

Videos from the scene show people running for their lives, not knowing where to go for safety. Witnesses reported seeing a young man wearing a camouflage uniform and hat with a long rifle with removable ammunition magazines. The first 911 calls came in at 5:41 p.m., and within a minute three Gilroy police officers had engaged the shooter, fatally wounding him with pistol shots.

Gilroy Police Chief Scot Smithlee said the gunman had appeared to access the festival grounds via a creek and cut through a perimeter fence with some sort of tool, bypassing metal detectors at the event entrance. The three fatalities included a six-year-old boy, a 13-year-old girl and a 25-year-old man. At least a dozen others were wounded, some remaining in critical condition in area hospitals as of Monday evening.

Gilroy is a largely agricultural community of about 50,000, some 80 miles southeast of San Francisco. The working-class city is integrated, with about equal numbers of Latinos and whites. Known as the Garlic Capital of the World, Gilroy prides itself on its annual Garlic Festival, which attracts tens of thousands of people. As in the case with similar mass shootings, those setting out on Sunday to enjoy the day at the festival could not know that it would end in such horror.

Authorities have identified the shooter as 19-year-old Santino William Legan. They say his weapon was an AK-47-type assault rifle he had apparently purchased legally in Nevada on July 9.

In Legan’s state of California, it is illegal for people under 21 to buy such weapons. In Nebvada it is not.

Although police were quick to characterize the shooting rampage as “random”, upon closer examination it fits the pattern of similar bloody outbursts over the last few years.

It appears that the young gunman scoped out the event for attack. In an Instagram account bearing the suspect’s name created five days ago, one post was a photo of people walking around the Garlic Festival.

Another showed a sign of Smokey Bear saying, “Fire Danger High Today.” The caption read: “Read Might is Right by Ragnar Redbeard”, adding, “Why overcrowd towns and pave more open space to make room for hordes of mestizos and Silicon Valley white twats?” A “mestizo” is a person of mixed descent, usually white and Hispanic, or white and American Indian. The term was used in the casta system during the Spanish Empire’s control of colonies in the Americas and Asia.

The racist overtones are clear. But even more ominously, the book reference is to Might is Right or The Survival of the Fittest, a social Darwinist, white supremacist screed first published in 1890. The book’s author drew his inspiration from—among others—German philosopher Friedrich Nietzsche, who championed nihilistic, anti-Enlightenment views, including a theory of master-slave morality. Nietzsche’s work became associated with fascism and Nazism.

One passage in Might is Right reads: “The [eighteenth century United States] Declaration of Independence commences by proclaiming an unctuous falsehood, a black, degrading, self-evident lie—a lie which no one could possibly believe but a born fool. With insolent effrontery it brazenly proclaims as ‘a self-evident truth’ that ‘all men are created equal.’”

And further: “You have only to look at some men, to know that they belong to an inferior breed. Take the Negro for example. … Similar language may be applied to the Chinaman, the Coolie, the Kanaka, the Jew, and to the rotten-boned, degenerates of Anglo-Saxonism, rich and poor. Vile indeed are inhabitants of those noxious cattle kraals: London, Liverpool, New York, Chicago, New Orleans” (emphasis added—Kanaka refers to a Pacific Islander enslaved as an indentured servant in Australia; kraal is an Afrikaans word for an enclosure for livestock within an African village).

Changing the specific references, one could easily swap out “those noxious cattle kraals: London, Liverpool, New York, Chicago, New Orleans” with Donald Trump’s recent tweets about Rep. Elijah Cummings’ congressional district in Baltimore, which the president derided as a “rat and rodent infested mess,” a “disgusting & filthy place.” He stated, “No human being would want to live there.”

Trump’s racist tirades against Cummings and the city of Baltimore followed on the heels of his attacks on four Democratic congresswomen two weeks ago, in which he wrote that they should “go back” to the “crime infested places from which they came.”

When he speaks these foul obscenities, Trump is appealing to elements like the Gilroy shooter. This is not just verbal jousting but is part of a calculated effort to base his reelection campaign on the incitement of an openly fascistic movement.

An examination of two of the most heinous mass shootings in the past year points to the type of forces Trump and his fascistic advisers seek to rally, both in the US and internationally:

  • The Pittsburgh synagogue shooting on October 27, 2018, in which 11 were killed, and seven injured. Shooter Robert Bowers, an anti-Semite and neo-Nazi, sympathized with the Trump administration’s persecution of immigrants, but regarded them as insufficient. He wrote in one post: “There is no #MAGA [Make America Great Again] as long as there is a k**e infestation.”
  • The mosque shootings in Christchurch, New Zealand, on March 15, 2019, in which 51 were killed, and 49 injured. The shooter, self-described white supremacist Brenton Tarrant, wrote a 74-page manifesto titled “The Great Replacement”—a reference to “white genocide” theories—calling for all non-European immigrants, whom he claimed to be “invading his land”, to be removed. He praised Trump as “a symbol of renewed white identity and common purpose.”

Trump’s fascistic entreaties—and in these he is joined by his counterparts in Europe and elsewhere—are combined with a vicious attack on immigrants from Central America fleeing poverty and violence, whom he brands as “invaders”, “rapists” and “criminals.” The term “concentration camps” is an accurate description of the cages in which men, women, children and infants are held without access to proper food, clothing, sanitation and medical care.

It is 20 years since the horrifying massacre at Columbine High School in Colorado, when on April 20, 1999, students Eric Harris and Dylan Klebold walked into the school armed with assault rifles and pipe bombs, killing 12 students and one teacher before turning the guns on themselves.

The WSWS wrote at the time of the indices of social and political dysfunction that produce such events: “Vital indicators of impending disaster might include: growing polarization between wealth and poverty; atomization of working people and the suppression of their class identity; the glorification of militarism and war;

One of the Columbine murderers had wanted to join the NATO war on Yugoslavia, but was turned down for medical reasons.

the absence of serious social commentary and political debate; the debased state of popular culture; the worship of the stock exchange; the unrestrained celebration of individual success and personal wealth; the denigration of the ideals of social progress and equality.”

There is little need for correction to these words, only their amplification. The ensuing years have seen both a burgeoning of social inequality and an increased drive to war. Two-and-a-half years after Columbine, on September 11, 2001, the World Trade Center and the Pentagon were hit by a terrorist attack, killing nearly 3,000 and injuring twice that many.

The US government has never explained how men under surveillance by the FBI were able to carry out the attack. The George W. Bush administration seized on 9/11 to inaugurate the “war on terror”, which was the basis for taking the US into war first in Afghanistan and then in Iraq, laying waste to these countries and resulting in countless deaths and millions of global refugees—all on the basis of lies.

The fascistic rantings of Donald Trump are the logical expression and extension of these policies of the US ruling elite. The mass shootings such as Sunday’s in Gilroy are a warning of the necessity of the working class to arm itself politically against this threat.

How monarch butterflies winter

This 9 April 2019 video says about itself:

Why Are 300 Million Butterflies In This Forest?

The monarch butterfly migration is one of nature’s greatest events. This orange-winged wonder travels up to 4,500 km from all over North America to spend the winter hanging from oyamel fir trees in central Mexico’s mountain forests. I got to go there. Seeing tens of millions of butterflies dangling from the treetops is a truly breathtaking sight. But how does an animal with a brain the size of a poppy seed navigate to this one special place, especially since the last monarchs to make the trip lived 4 or 5 generations earlier? Get ready for an amazing story of science, instinct, and navigation.

From the University of Michigan in the USA:

Monarch butterflies rely on temperature-sensitive internal timer while overwintering

July 24, 2019

The fact that millions of North American monarch butterflies fly thousands of miles each fall and somehow manage to find the same overwintering sites in central Mexican forests and along the California coast, year after year, is pretty mind-blowing.

Once they get there, monarchs spend several months in diapause, a hormonally controlled state of dormancy that aids winter survival. Though diapause is not as obviously impressive as the celebrated annual migrations, it holds mysteries that have perplexed scientists who study biological timing.

Weeks before warming temperatures and longer days signal to the monarchs that it’s time to mate and begin spring’s northward migration, an internal timer goes off like an alarm clock to rouse the insects, telling them it’s time to end diapause and prepare for the critical upcoming events.

Studies in other organisms have shown that cold temperatures can influence the diapause-termination timer, and University of Michigan biologist D. André Green suspected the same is true for monarchs. His study at monarch overwintering sites in central California confirmed it, and his gene expression analyses help explain how cold temperature speeds up that internal timer.

“These results are particularly interesting because they address a counterintuitive result: How does cold temperature, which normally slows down an organism’s metabolism and development, speed up diapause? This work is one of the first to provide insights into this question,” said Green, a President’s Postdoctoral Fellow in the U-M Department of Ecology and Evolutionary Biology who began the work while at the University of Chicago.

The findings have important implications for North America’s monarchs — whose populations have declined steadily for decades at the overwintering sites — as the climate changes, Green and co-author Marcus Kronforst of the University of Chicago wrote in a Molecular Ecology study scheduled for publication July 24.

“Understanding how diapause dynamics are affected by environmental and anthropogenic factors at their overwintering sites may be critical for understanding North American monarch population decline and guiding future conservation efforts, a point highlighted by the record low number of monarchs recorded in the western North American monarch population in 2018,” Green and Kronforst wrote.

The findings also suggest that monarchs will act as an important sentinel species for monitoring environmental change and disturbance at overwintering sites. If diapause ends too early, monarchs may lose some of the protective time the dormancy period provides.

Green’s study involved capturing female monarch butterflies at overwintering sites in central California in November 2015, after they entered diapause. The live insects were brought back to the Chicago lab.

In an environmental chamber there, the butterflies were exposed to temperatures and day lengths approximating November in central California: 10 hours of light at 63 degrees Fahrenheit, followed by 14 hours of darkness at 50 degrees.

In December and again in January, Green’s team returned to the same overwintering sites, live-captured additional female monarchs and shipped them to the lab. In the wild, those winter-caught butterflies also experienced short days, along with nighttime temperatures that dipped below 50 degrees.

Green then compared the reproductive maturity of the different groups by counting the number of eggs in each female. An abundance of mature eggs is an indication that the female has terminated diapause, while a paucity of mature eggs indicates that she is still in diapause.

“The monarchs collected from the wild in December showed increased reproductive development compared to the monarchs that had been in the laboratory since November,” Green said. “This indicated that an environmental condition in the wild — cold temperature — sped up the timer.”

As part of the same study, Green also analyzed gene expression in the different groups of monarchs to understand how the internal timer works. Results suggest that transient markings on histones — proteins around which DNA winds and that control gene expression — may act as a timing mechanism.

The results also show that calcium signaling in the butterfly’s head is key, potentially linking the accumulation of cryoprotectants during cold weather to the internal timer.

The research was supported by the National Science Foundation, U.S. Fish and Wildlife Service, and National Institutes of Health. Wild monarchs were collected on private property near Pismo Beach, California, with permission of the landowners.

Green is currently working on a separate study of monarch migration at a study site in U-M’s Matthaei Botanical Gardens.

Californian sea otters and archaeology

This September 2018 says about itself:

Cute Sea Otter Behaviour Decoded

From holding paws to rubbing their faces, sea otters are otter-ly adorable. But why do they do it? Discover the science behind the cute.

From the Max Planck Institute for the Science of Human History in Germany:

Sea otters’ tool use leaves behind distinctive archaeological evidence

Researchers used an interdisciplinary approach combining ecology and archaeological methods to study sea otters’ past behavior

March 14, 2019

An international team of researchers has analyzed the use by sea otters of large, shoreline rocks as “anvils” to break open shells, as well as the resulting shell middens. The researchers used ecological and archaeological approaches to identify patterns that are characteristic of sea otter use of such locations. By looking at evidence of past anvil stone use, scientists could better understand sea otter habitat use.

Sea otters are an especially captivating marine mammal, well known for their use of rocks to break open shells. Sea otters are estimated to have once numbered between 150,000-300,000 individuals and their range stretched from Baja California, Mexico, around the northern Pacific Rim to Japan. Their numbers were dramatically reduced by the fur trade. In California, the southern sea otter population was reduced to around 50 individuals, but a massive conservation effort has resulted in increasing their numbers to around 3000 today. However, the southern sea otter is still considered threatened.

Sea otters are unique for being the only marine mammal to use stone tools. They often use rocks to crack open shells while floating on their back, and also sometimes use stationary rocks along the shoreline as “anvils” to crack open mollusks, particularly mussels. A joint project including the Max Planck Institute for the Science of Human History, the Monterey Bay Aquarium and the University of California, Santa Cruz, among others, has resulted in a first-of-its-kind interdisciplinary study published in Scientific Reports, combining ten years of observations of sea otters with archaeological methods to analyze sea otter use of such anvil stones, also known as emergent anvils.

Sea otter use of anvil stones leaves distinctive wear and shell middens that are characteristic of sea otters

Researchers spent ten years between 2007-2017 observing sea otters consuming mussels at the Bennett Slough Culverts site in California. Their analysis identified that mussels were the most common prey eaten at the site and were the only prey for which the sea otters used stationary anvil stones. The sea otters used such stones for about 20% of the mussels they consumed.

Interestingly, careful analysis of the stationary anvil stones using archaeological methods showed that their use resulted in a recognizable damage pattern that was distinguishable from what would be caused by human use. For example, the sea otters preferentially struck the mussels against points and ridges on the rocks, and struck the rocks from a position in the water, rather than from the land or from on top of the rock.

Consistent damage pattern on broken mussel shells indicates probable “pawedness” in sea otters

In addition to the stones themselves, the researchers also carefully analyzed the mussel shells left around the stationary anvils. The researchers took a random sample of the shell fragments from these shell middens, which likely contained as many as 132,000 individual mussel shells. They found an extremely consistent damage pattern, with the two sides of the mussel shell still attached, but a diagonal fracture running through the right side of the shell.

“The shell breakage patterns provide a novel way to distinguish mussels broken by sea otter pounding on emergent anvils from those broken by humans or other animals,” explains Natalie Uomini of the Max Planck Institute for the Science of Human History. “For archaeologists who excavate past human behavior, it is crucial to be able to distinguish the evidence of sea otter food consumption from that of humans.”

In combination with analysis of videos they took of the otters using the anvils, researchers could see that the otters held the shells evenly in both paws, but when striking the shell against the anvil tended to have their right paw slightly on top. Though the total number of otters observed was small, these results suggest that otters may exhibit handedness, or “pawedness,” as do humans and many other mammals.

Potential for archaeological investigations of past sea otter behavior

The researchers hope that the study will be useful for archaeologists working with coastal populations, as a way to distinguish between human and sea otter use of rocks and consumption of marine resources. Additionally, the research could be helpful in future studies of the geographic spread of stationary anvil use throughout the former sea otter range, and how far into the past this behavior extends.

“Our study suggests that stationary anvil use can be detected in locations previously inhabited by sea otters. This information could help to document past sea otter presence and diet in locations where they are currently extirpated,” explains Jessica Fujii of the Monterey Bay Aquarium.

“More broadly,” she adds, “the recovery of past animal behavioral traces helps us to understand the evolution of behaviors like stone anvil use, which is rare in the animal kingdom and is extremely rare in marine animals. We hope that this study establishes a new path for the growing field of animal archaeology.”

Sea otters have very low genetic diversity, scientists report. Their findings have implications for the conservation of rare and endangered species, in which a lack of genetic diversity can increase the risk of extinction: here.

American chickadees with good memory survive winters

This December 2014 video says about itself:

Mountain Chickadee – carnivore

Mountain Chickadee eating from a deer carcass. Is it finding bugs? At the end, a slower view reveals how it is pulling flesh off the carcass.

From the University of Nevada, Reno in the USA:

Natural selection and spatial memory link shown in mountain chickadee research

February 12, 2019

Chickadees with better learning and memory skills, needed to find numerous food caches, are more likely to survive their first winter, a long-term study of mountain chickadees has found.

Enhanced spatial cognition and brain power evolves via natural selection, an elaborate study of hundreds of mountain chickadees in the Sierra Nevada has found. Using passive integrative transponder (PIT) tags in combination with radio frequency identification-equipped feeders, scientists at the University of Nevada, Reno have tracked feeding behaviors and measured learning and memory of these non-migratory birds that live year-round in the high-elevation forest northwest of Truckee, California.

“This is a unique program, set in the wilderness, so we get unique results,” Vladimir Pravosudov, lead researcher and biology professor at the University’s College of Science, said. “Over the years, we’ve banded and tagged thousands of chickadees and observed their spatial cognition using custom-designed and built feeders that allow us to track how individuals learn and remember. And now we have tested whether individuals with better learning and memory performance are more likely to survive the winter.”

Ben Sonnenberg, a doctoral student in the laboratory of Pravosudov (as a part of the Ecology, Evolution and Conservation Biology Graduate program) is the lead author, and Pravosudov is a corresponding author, on a scientific paper, based on the research, published Feb. 7 in the journal Current Biology.

‘We’re looking at how natural selection can generate differences in the birds living in different environments, and we now have direct evidence that selection is acting on chickadees’ spatial cognition, which is needed to find tens of thousands of previously made food caches required to survive the winter,” Pravosudov said. “Our new evidence fully support our previous comparative studies showing that chickadees living in harsh winter conditions at high elevations have better memory and larger hippocampus, a brain structure associated with memory. Our new data show that better learning and memory in these birds at high elevations are due to strong natural selection.”

Pravosudov and his team of three graduate students visit their field sites near the University of California, Berkeley Sagehen Creek Field Station north of Truckee, California multiple times a week, year-round, including in some of the harshest Sierra Nevada winter weather. The field sites are about 40 miles from campus, so traveling during snowstorms is slow, and then they must use over-snow vehicles to go the last 10 miles to the high elevation site near Carpenter’s ridge, at about 8,300 feet in elevation, often blazing a trail through four feet of new snow.

“Results like these (about natural selection) make the long days of digging out snowmobiles, shoveling snow and programming our chickadee feeders from underneath a tarp in sleeting weather worth the effort twice over,” graduate student Sonnenberg said.

Four over-snow vehicles are used to transport the researchers and gear to their sites, and sometimes they have to ski to get there because their vehicles can’t get through the deep snow.

Their destination at high elevation is the centerpiece for this study, with two identical metal frameworks — arrays — that hold eight feeders each. Access to the feeders is regulated by RFID activated doors and the feeder arrays can be raised and lowered depending on the snow depth. The frameworks hang by cables between trees in the forest that reaches 8,300 feet above sea level. Two similar arrays are set up at their lower elevation study area about four miles away and a few thousand feet lower in elevation.

Each bird has its own PIT tag ID and the feeder doors can be programmed to let in whichever birds Pravosudov and his team decide. The data, such as number of visits by an individual bird to each feeder, the time of day they feed and what other chickadees they share the feeder with, are automatically recorded by RFID boards and stored on memory cards which need to be regularly retrieved to download the data.

By assigning each bird only one rewarding feeder, researchers are able to measure learning and memory by recording how many non-rewarding, or ‘wrong,’ feeders birds visit before they find their rewarding feeder. As birds learn, they are expected to stop visiting all but the rewarding feeder.

“It’s a simple system, we built it all in-house, with many design and build versions as we adapted them to the environment,” Pravosudov said. “We collaborate with Dr. Eli Bridge from University of Oklahoma on RFID designs. Our feeders are field tested, needing to survive the elements and other animals — squirrels when the snow is deep, and bears all the time — who are looking to steal the bird seed from the experiment feeders. Bears have destroyed many feeders before we figured out how to avoid them.”

“We follow chickadees their entire lives; we get the whole big picture,” he said. “Mountain chickadees have an average lifespan of one and a half years, but our oldest is seven years old. The highest mortality occurs in juvenile birds during their first winter. Survivability is higher in adults once they survived their first winter because they are the ones who have better learning and memory abilities, allowing them to find where their food is cached. As much as 50 percent of the population dies off each year in the mountain environment; if they can’t remember well where their food is cached, they are not likely to survive.”

When comparing the juveniles who survived the first year to those who did not, learning and memory performance was better in those who survived. The research team also found that cognitive abilities remained stable as the birds aged.

The wild food-caching mountain chickadees don’t migrate, they stay mostly at the same sites they settled on after they dispersed from where they hatched. At the Sagehen forest, there are no birds that permanently moved between the researchers’ low and high elevation sites, which are six miles apart.

“We have banded several thousand chickadees over the years and we have never seen any birds permanently moving between elevations,” Pravosudov, who teaches animal behavior and behavioral ecology, said. “These birds are easier to study because they are in one spot their entire life, dependent on food caches to make it through the harsh winters.”

“The ability to track individual mountain chickadees throughout their lifetime in the Sierra Nevada mountains has been extremely exciting and rewarding,” Sonnenberg said. “I was drawn to UNR and Vladimir’s lab because there is no other system like it.”

Vladimir has suspected for years that spatial memory is being shaped by natural selection and being able to take part in such a major step in confirming these ideas is extremely special, he said.

“Our results provide the first direct evidence for natural selection on spatial cognition in wild food-caching mountain chickadees,” he said. “Taken together, our results suggest that natural selection associated with environmental differences, like those in winter conditions between high and low elevations in the mountains, might be generating intraspecific differences in cognitive abilities. Our evidence suggests that natural selection, rather than some other potential variables that critics have said could be responsible for the results of earlier comparative studies inconclusive, is the main driver of such differences.”

The strongest supporting evidence comes from spatial learning and memory performance, as results from all three comparisons in the study are consistent with natural selection:

  1. Adults showed better spatial learning and memory performance than first-year juveniles;
  2. There was no significant difference in performance of the same cohort of chickadees that was first tested as first-year birds and then as adults, in other words they did not improve cognitive performance with experience; and
  3. Spatial cognitive performance was a significant predictor of survival in first-year juvenile chickadees; birds that survived their first winter season showed significantly better performance in the spatial learning and memory tasks compared to birds that died.

Pravosudov received a National Science Foundation grant in 2014 to conduct this study. Two other NSF grants, one awarded to collaborator Eli Bridge and one awarded to Carrie Branch, were part of the funding for this project.

Co-authors on the scientific paper in Current Biology are Benjamin Sonnenberg, University of Nevada, Reno; Carrie Branch, former doctoral student at the University of Nevada, Reno and now a postdoc at Cornell Lab of Ornithology; Angela Pitera, University of Nevada, Reno; and Eli Bridge, University of Oklahoma, Oklahoma Biological Survey.

Pravosudov’s is currently the only lab in the world that carries systematic study of spatial learning and memory in wild food-caching birds in extreme environmental conditions.

He’s been studying mountain chickadees in the Sierra since 1999 starting as a post-doc at the University of California, Davis. Before that, he studied European food-caching tits (related to North American chickadees) above the Arctic Circle in northern Russia and then in North Eastern Siberia. Pravosudov’s lab has published 21 papers about chickadees since 2015, with more in the pipeline. His curiosity and drive to learn more continues today.

“We now have DNA of all the birds we’ve banded, so next we are collaborating on genomics projects to investigate genomic bases of variation in learning and memory; maybe this summer we’ll have a paper on our findings using full genomes of numerous chickadees with known learning and memory performance,” he said.

He is a fellow of the American Ornithological Society, recognizing his “exceptional and sustained contributions to ornithology” and an elected fellow of the Animal Behavior Society.

Californian islands’ small mammoths

This 5 February 2019 video from the USA says about itself:

The Island of Shrinking Mammoths

The mammoth fossils found on the Channel Islands off the coast of southern California are much smaller than their relatives found on the mainland. They were so small that they came to be seen as their own species. How did they get there? And why were they so small?

Thanks to Julio Lacerda and Studio 252mya for the Palaeoloxodon illustrations.