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.

Advertisements

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.

Why Californian honeybees die


This 6 June 2017 video from the USA says about itself:

What is Killing the Bees

Neonicotinoid insecticides are used to manage insect pests on fruits and vegetables that also rely on pollination. In addition, these crops frequently neighbor and are rotated with large acreage field crops containing neonicotinoid seed treatments such as corn, resulting in potential non-target exposure of honey bees to insecticides.

This video highlights current efforts by Purdue entomologists—Ian Kaplan, Christian Krupke, Rick Foster—through a USDA-SCRI (specialty crop research initiative) grant to evaluate the impact of neonicotinoids on managed and wild pollinators of cucurbits in the Midwestern U.S. and determine how best to balance pest management with conserving pollinator health.

From Ohio State University in the USA:

Culprit found for honeybee deaths in California almond groves

Researchers and industry leaders working to stop insecticide use during bloom

February 4, 2019

Summary: ‘Fungicides, often needed for crop protection, are routinely used during almond bloom, but in many cases growers were also adding insecticides to the mix. Our research shows that some combinations are deadly to the bees, and the simplest thing is to just take the insecticide out of the equation during almond bloom.’

It’s about time for the annual mass migration of honeybees to California, and new research is helping lower the chances the pollinators and their offspring will die while they’re visiting the West Coast.

Each winter, professional beekeepers from around the nation stack hive upon hive on trucks destined for the Golden State, where February coaxes forward the sweet-smelling, pink and white blossoms of the Central Valley’s almond trees.

Almond growers rent upwards of 1.5 million colonies of honeybees a year, at a cost of around $300 million. Without the bees, there would be no almonds, and there are nowhere near enough native bees to take up the task of pollinating the trees responsible for more than 80 percent of the world’s almonds. The trouble was, bees and larvae were dying while in California, and nobody was sure exactly why. The problem started in adults only, and beekeepers were most worried about loss of queens.

Then in 2014, about 80,000 colonies — about 5 percent of bees brought in for pollination — experienced adult bee deaths or a dead and deformed brood. Some entire colonies died.

With support from the Almond Board of California, an industry service agency, bee expert Reed Johnson of The Ohio State University took up the task of figuring out what was happening. Results from his earlier research had shown that some insecticides thought safe for bees were impacting larvae. Building on that, Johnson undertook a new study, newly published in the journal Insects, that details how combinations of insecticides and fungicides typically deemed individually “safe” for honeybees turn into lethal cocktails when mixed.

Johnson, an associate professor of entomology, and his study co-authors were able to identify the chemicals commonly used in the almond groves during bloom because of California’s robust and detailed system for tracking pesticide applications. Then, in a laboratory in Ohio, they tested combinations of these chemicals on honeybees and larvae.

In the most extreme cases, combinations decreased the survival of larvae by more than 60 percent when compared to a control group of larvae unexposed to fungicides and insecticides.

“Fungicides, often needed for crop protection, are routinely used during almond bloom, but in many cases growers were also adding insecticides to the mix. Our research shows that some combinations are deadly to the bees, and the simplest thing is to just take the insecticide out of the equation during almond bloom,” he said.

“It just doesn’t make any sense to use an insecticide when you have 80 percent of the nation’s honeybees sitting there exposed to it.”

The recommendation is already catching on and has been promoted through a wide array of presentations by almond industry leaders, beekeepers and other experts and has been included in the Almond Board’s honeybee management practices. Many almond growers are rethinking their previous practices and are backing off insecticide use during almond bloom, Johnson said.

That’s good news for bees, and doesn’t appear to be harming the crops either, he said, because there are better opportunities to control problematic insects when almonds are not in bloom.

“I was surprised — even the experts in California were surprised — that they were using insecticides during pollination,” Johnson said.

While these products were considered “bee-safe,” that was based on tests with adult bees that hadn’t looked into the impact they had on larvae.

“I think it was a situation where it wasn’t disallowed. The products were thought to be bee-safe and you’ve got to spray a fungicide during bloom anyway, so why not put an insecticide in the tank, too?”

Insecticides are fairly inexpensive, but the process of spraying is labor-intensive, so growers choosing to double up may have been looking to maximize their investment, he said.

“The thing is, growers were using these insecticides to control a damaging insect — the peach twig borer — during this period, but they have other opportunities to do that before the bees enter the almond orchards or after they are gone,” Johnson said.

This research could open the door to more study of fungicide and pesticide use on other bee-dependent crops, including pumpkins and cucumbers, Johnson said.

When a honey bee turns 21 days old, she leaves the nest to look for pollen and nectar. For her, this is a moment of great risk, and great reward. It’s also the moment at which she becomes recognizable to other bees.

Honey bee colonies foraging on land with a strong cover of clover species and alfalfa do more than three times as well than if they are put next to crop fields of sunflowers or canola, according to a new study: here.

Elephant seals benefit from United States government shutdown


This 29 January 2019 video from California in the USA says about itself:

Government Shutdown Brings Elephant Seals To Point Reyes Beach

Elephant seals used the opportunity of an empty Drake’s Beach on Point Reyes National Seashore – due to the government shutdown – to gather for mating and bearing pups. Wilson Walker reports.

Donald Trump’s shutdown blackmail to try to build his wall was a disaster for many workers; and for national parks and their wildlife. At least, one good consequence, for the elephant seals.

SECOND SHUTDOWN LOOMS AS TALKS BREAK DOWN Talks between congressional Republicans and Democrats aimed at averting another government shutdown have broken down without an agreement. Last month’s federal funding deal runs out on Friday. Acting White House chief of staff Mick Mulvaney said over the weekend another partial government shutdown “absolutely cannot” be ruled out.  [Reuters]

House finches in California, USA


This 4 May 2014 video from the USA says about itself:

Backyard Bird Watching: House Finch Nest 5 Weeks Complete Documentary

Filmed over the course of 5 weeks, from eggs to baby flying away, shot in Pasadena, California.

From the Cornell Lab of Ornithology in the USA, 23 January 2019:

New Study Focuses on House Finches

A study spanning more than a century of House Finch data suggests that as California’s spring temperatures get warmer, the birds are laying eggs earlier in the season. The new study is based on data from our nest records, along with nest specimens from museums going back to 1895.

Dr. Heather Watts of Washington State University spearheaded the investigation on these vegetarian finches. The paper notes that while insect-eating birds have been documented shifting their egg-laying in association with warmer spring temperatures, birds which eat a plant-based diet (about 28 percent of species globally) have been understudied. The House Finch, which is also declining in California, was therefore a good study species. Read more about this research in our latest blog post.

The small songbird, which famously landed at a Bernie Sanders election rally in 2016, was a female house finch.

Beaked whales’ feeding disturbed by navy sonar


This June 2017 video says about itself:

Sea Shepherd Captures NEVER SEEN BEFORE drone footage of the rare Cuvier’s Beaked Whales (Ziphius cavirostris) while conducting research on Mexico’s Guadalupe Island.

This is the first ever footage of a mother and calf pair of this species.

From the Monterey Bay Aquarium Research Institute in the USA:

Why do beaked whales return to a Navy sonar range despite frequent disturbance?

Scientists say it’s the food

January 29, 2019

Using data from underwater robots, scientists have discovered that beaked whales prefer to feed within parts of a Navy sonar test range off Southern California that have dense patches of deep-sea squid. A new study published in the Journal of Applied Ecology shows that beaked whales need these prey hotspots to survive, and that similar patches do not exist in nearby “sonar-free” areas.

For decades, the U.S. Navy has used high-powered sonar during anti-submarine training and testing exercises in various ocean habitats, including the San Nicolas Basin off Southern California. Beaked whales are particularly sensitive to these kinds of military sonars, which sometimes result in mass stranding events. Following legal action from environmental activists related to these risks, the Navy modified some training activities, created “sonar-free” areas, and spent more than a decade and tens of millions of dollars trying to find ways to reduce the harm to beaked whales and other mammals.

The new research, led by Brandon Southall at the University of California, Santa Cruz, and Kelly Benoit-Bird at the Monterey Bay Aquarium Research Institute, aimed to better understand why whales keep returning to the test range despite the risks.

The researchers equipped an underwater robot with echosounders to measure the abundance, density, and sizes of deep-sea squids in different parts of the Navy test range, as well as in nearby waters. They also developed an “energy budget” for beaked whales, showcasing the costs — in time and calories — of hunting for squid. This helped the researchers estimate how many dives the whales needed to make in order to get enough food to survive in different areas.

“Beaked whales work very hard to obtain their food. They are essentially living paycheck to paycheck”, said Benoit-Bird. Unlike many baleen whales with significant energy reserves, beaked whales can’t afford to expend too much energy on a dive that doesn’t result in capturing many squid. In areas where the concentration of prey is low, the beaked whales must work harder and expend more calories — making reproduction and raising young that much more challenging. Some of the areas under study were so poor in terms of prey that whales likely could not meet their basic energetic requirements if they only fed there.

“Despite how things might look from the surface, the deep sea is not uniform,” Benoit-Bird added. “There are pockets of wealth where squid are abundant, and beaked whales know exactly how to find those hot spots.” It turns out that a portion of the Navy test range off Southern California encompasses one of these hot spots — an area rich in squid.

In fact, squid were 10 times more abundant higher in the area preferred by the whales. In this preferred area, the whales could get enough food by making just one dive a day. In a nearby sonar-free area (established with the idea that beaked whales could shelter in these areas while the sonar tests were underway) the whales would need to make between 22 and 100 dives per day to get enough food — something that would be difficult or impossible to do.

“Our findings, based on a novel integration of active sonar imaging and passive listening technologies, have multiple management implications”, explained Southall. “They provide direct information to the Navy and federal regulators to better manage important and impacted habitat areas off California. And they give us new data on foraging ecology for population-level models of disturbance that have been at the heart of recent debate and litigation over spatial management and proposed sonar exclusion zones.”

This study is the first to link habitat quality with beaked whale behavior in such fine spatial scales. It also demonstrates that scientists can’t assess the quality of deep-sea habitats by simply making measurements at the ocean surface, or even by measuring the physical and chemical properties of the deep ocean. Direct measurements of the prey environment at the depths where animals are feeding, coupled with observations of when and where animals are foraging, are critical.

Until now, collecting such detailed data, even over small time and space scales, was virtually impossible. The researchers are now working on tools that will help them study predators and prey over longer time periods, and in other areas where the Navy operates high-powered sonar. Similar field-research and modeling techniques could also be used to assess the potential impacts of other human activities that may disturb ocean animals, such as shipping traffic or offshore oil and gas development.

Marine mammals are particularly sensitive to noise pollution because they rely on sound for so many essential functions, including communication, navigation, finding food, and avoiding predators. An expert panel has now published a comprehensive assessment of the available science on how noise exposure affects hearing in marine mammals, providing scientific recommendations for noise exposure criteria that could have far-reaching regulatory implications: here.