Key S. African leopard population 'crashing', study warns

The leopard population in a region of South Africa once thick with the big cats is crashing, and could be wiped out within a few years, scientists warned on Wednesday.

The clash between humans and leopards, experts agree, is mostly due to humanity's expanding footprint, 
especially in Africa, whose population is set to expand by more than a billion before mid-century 
[Credit: AFP/Gianluigi Guercia]

Illegal killing of leopards in the Soutpansberg Mountains has reduced their numbers by two-thirds in the last decade, the researchers reported in the Royal Society Open Science journal.

"If things don't change, we predict leopards will essentially disappear from the area by about 2020," lead author Samual Williams, a conservation biologist at Durham University in England, told AFP.

"This is especially alarming given that, in 2008, this area had one of the highest leopard densities in Africa."

The number of leopards in the wild worldwide is not known, but is diminishing elsewhere as well. The "best estimate" for all of South Africa, said Williams, is about 4,500.

What is certain, however, is that the regions these predators roam has shrunk drastically over the last two centuries.

The historic range of Panthera pardus, which includes more than half-a-dozen sub-species, covered large swathes of Africa and Asia, and extended well into the Arabian Peninsula.

Leopards once roamed the forests of Sri Lanka and Java unchallenged.

Today, they occupy barely a quarter of this territory, with some sub-species teetering on the brink of extinction, trapped in one or two percent of their original habitat.

Leopards were classified last year as "vulnerable" to extinction on the International Union for the Conservation of Nature's Red List of endangered species, which tracks the survival status of animals and plants.

South Africa recently suspended trophy hunting of leopards, though experts agree this is not a major cause of the population decline.

Bleak findings

A 2008 census of leopards in the 6,800-square kilometre (2,600-square mile) Soutpansberg Mountains found a robust population of nearly 11 adult cats for each hundred square kilometres (39 square miles).

South Africa recently suspended trophy hunting of leopards, though experts agree this 
is not a major cause of the population decline [Credit: AFP/Alexander Joe]

To find out how the carnivores had fared since then, Williams and his team set up four dozen motion-triggered camera traps across the area, and left them in place from 2012 to 2016.

The cameras captured a total of 65 individual leopards during the four-year period: 16 adult males, 28 adult females and 21 younger cats.

They also fitted eight adults with GPS collars to track their movements -- or lack thereof.

Only two of the GPS-tagged leopards survived the monitoring period. Three were done in by snares, one was shot by a local resident whose cattle had been attacked, and two went missing, probably killed since they also disappeared from camera surveillance.

A statistical analysis of the results showed "a 66 percent decline over a period just over 7.5 years," the study concluded.

Ironically, the bleak findings helped conservationists and local officials raise money to hire a "community engagement officer."

Lake Fundudzi sits among the foothills of South Africa's Soutpansberg Mountains 
in the northern province of Limpopo [Credit: AFP/Alexander Joe]

"One of the things he does is help local people adopt non-lethal techniques" to prevent leopards from attacking cattle and other livestock, including the use of guard dogs, Williams added.

But the clash between humans and big carnivores, experts agree, is mostly due to humanity's expanding footprint, especially in Africa, whose population is set to expand by more than a billion before mid-century.

As a result, the habitats of most wild megafauna are diminishing, and getting chopped up into smaller and smaller parcels.

"It is extremely alarming that the trends that we are reporting exemplify trends in large carnivores globally," Williams said.

Studies in Africa of lions, black-backed jackals and bat-eared foxes have showed similar rates of decline.

Author: Marlowe Hood | Source: AFP [April 19, 2017]

byUnknown

in Africa, Endangered Species, Natural Heritage, South Africa, Wildlife

April 19, 2017

Key S. African leopard population 'crashing', study warns

The leopard population in a region of South Africa once thick with the big cats is crashing, and could be wiped out within a few years, scie...

Read More

Tracing the puzzling origins of clinging jellyfish

For such small and delicate creatures, they can pack mighty painful stings. Known as clinging jellyfish because they attach themselves to seagrasses and seaweeds, Gonionemus is found along coastlines in the Pacific and Atlantic oceans, and in particular in waters near Vladivostok, Russia. Exactly how these jellyfish, long assumed to be native to the North Pacific, became so widely distributed throughout the world has perplexed researchers for decades.

Clinging jellyfish in waters near Vladivostok, Russia (like the one above) are known to cause severe sting reactions. 
Interest in the jellies has renewed in recent years, when stings with symptoms similar to those previously 
described  off of the Russian coast suddenly started occurring in Cape Cod and nearby regions 
[Credit: Lubov Petrova, Primorsky Aquarium]

Interest in the jellyfish has renewed in recent years, when stings with symptoms similar to those previously described off of the Russian coast -- including severe pain, respiratory and neurological symptoms -- suddenly started occurring in Cape Cod and nearby regions.

Now, the first genetic study of the diversity of clinging jellyfish populations around the globe has discovered some surprising links among distant communities of jellies and also revealed there may be more than one species of the infamous stinger. The paper published in the journal Peer J.

Annette Govindarajan, a biologist at Woods Hole Oceanographic Institution (WHOI) and lead author of the paper, has studied these jellies for the past three years with the ultimate goal of tracing the species' origin off the U.S. East Coast, where it is thought to be invasive.

The clinging jellyfish first appeared in the Cape Cod area in 1894. Scientists in Woods Hole studied the clingers in the early 1900s. Following an eelgrass die-off, their numbers dwindled. Then the tiny creatures, whose sizes range from about the diameter of a dime to a quarter, nearly vanished in the 1930s. Prior to that, says Govindarajan, researchers and others who were handling the jellies in Massachusetts made no reports of stings.

The clinging jellyfish first appeared in Cape Cod in 1894. Following an eelgrass die-off, the tiny creatures
 nearly vanished in the 1930s. It wasn't until 1990 that the jellies reappeared in the region and painful 
stings were first reported [Credit: Mary Carman, Woods Hole Oceanographic Institution]

"The Cape Cod populations were assumed to be a variety that didn't cause severe stings," Govindarajan adds. It wasn't until 1990 that the clinging jellyfish re-appeared in Cape Cod and painful stings were first reported. These observations lead Govindarajan and her colleague, WHOI researcher Mary Carman to suggest in a previous paper that an invasion from a toxic population had occurred.

The new study shows that the story is much more complex than previously thought. The researchers uncovered a genetic match between populations of clinging jellyfish in the Vladivostok, Russia-area -- specifically the area well known to cause severe sting reactions -- and those found along the U.S. East Coast in the Northwest Atlantic.

"We know the two regions share one genetic variant or haplotype," Govindarajan says. "In the Northwest Atlantic, this variant was actually most frequently found in eastern Long Island Sound. The details about how and when an invasion, or possibly multiple invasions, occurred aren't clear. Interestingly, we also found evidence that both regions may contain native forms."

Working with Carman and colleagues Marat Khaidarov and Alexander Semenchenko from the A.V. Zhirmunsky Institute of Marine Biology, National Scientific Center of Marine Biology, Far East Branch, Russian Academy of Sciences in Vladivostok, Russia, and John Wares from the University of Georgia, Govindarajan obtained tissue samples for DNA sequencing. The jellyfish samples came from several Atlantic and Pacific locations. Their analysis identified seven variants, some of which were specific to only one location, and others that were shared among communities in distant locations. Interestingly, jellies from the Northeast Pacific and Northeast Atlantic locations shared a haplotype that was sufficiently different from Northwest Atlantic and Northwest Pacific jellyfish, which suggests the possibility that the two related groups may represent different species of Gonionemus.

The researchers uncovered a genetic match between populations of clinging jellyfish in the Vladivostok,
Russia-area and those found along the U.S. East Coast (above) in the Northwest Atlantic 
[Credit: Annette Govindarajan, Woods Hole Oceanographic Institution]

"In the past, some people have suggested that the Atlantic and the Pacific jellies were different forms," Govindarajan says. "Others have suggested that jellies in the Atlantic were introduced from the Pacific. But what we found doesn't correspond exactly to either hypothesis. And it could be that what we have in the Northwest Atlantic and Northwest Pacific is not Gonionemus 'vertens' at all, as it has been called, but some other species of Gonionemus."

"The study documents what we suspected, that there are different types of Gonionemus jellies and some of these types co-occur in New England," says coauthor Carman. "Some types seem to have a toxic sting to people and some do not." Understanding the relationship between the genetic variants and toxicity is something the researchers would like to pursue in the future. "It could very well be that the toxicity is a function of both genetics and the environment, perhaps something in the environment is triggering the toxicity," Govindarajan says.

While the animals bloom in the summer months, beginning in June through September, Govindarajan says swimmers and beachgoers shouldn't be overly concerned as the fragile stingers are not found along sandy beaches in high-energy areas where there are waves.

"Unlike other jellies, it is unlikely that these would be in open water," she says. "We only see them in areas with eelgrass or seaweeds since they're able to cling to these surfaces with the sticky pads found on their tentacles." The lack of movement in open waters also makes the mystery of how the different varieties have become so widespread even more intriguing. The jellyfish are produced by microscopic polyps that are only about a millimeter or less in size, which Govindarajan says is a stage where they could easily hitchhike on a blade of eelgrass, an oyster shell or even a boat hull.

"At that stage, they're so tiny," she adds. "To find them is like finding a needle in a haystack."

Govindarajan and her coauthors hope to obtain funding to do additional genomic analyses that will give greater resolution and suggest genetic markers to help reveal more about the species and its toxicity. They hope this will lead to a better understanding of how invasive forms of the jellyfish are dispersing, so that further spread can be prevented. "With this study, we answered some questions, but it also opened up many others," says Govindarajan. "That's part of the scientific process. It's what makes it for me, personally, very interesting. I feel like I'm solving a mystery."

Source: Woods Hole Oceanographic Institution [April 18, 2017]

byUnknown

in Biology, Evolution, Genetics, Wildlife

April 18, 2017

Tracing the puzzling origins of clinging jellyfish

For such small and delicate creatures, they can pack mighty painful stings. Known as clinging jellyfish because they attach themselves to se...

Read More

Hunting accounts for massive declines in tropical animal populations

Hunting is a major threat to wildlife particularly in tropical regions, but a systematic large-scale estimate of hunting-induced declines of animal numbers was lacking so far. A study published in Science fills this gap. An international team of ecologists and environmental scientists found that bird and mammal populations were reduced within 7 and 40 km of hunters' access points, such as roads and settlements.

A decline of species abundance in hunted forest within 0-40 km from hunter access points 
[Credit: Radboud University/Joeri Borst]

Within these impact zones, mammal populations declined on average by 83% and bird populations by 58%. Additionally, the team found that commercial hunting had a higher impact than hunting for family food, and that hunting pressure was higher in areas with better accessibility to major towns where wild meat could be traded. The impact of hunting was found to be larger than the team expected. 'Thanks to this study, we estimate that only 17 percent of the original mammal abundance and 42 percent of the birds remain in hunted areas.'

The researchers synthesised 176 studies to quantify hunting-induced declines of mammal and bird populations across the tropics of Central and South America, Africa and Asia. The study was led by Ana Benítez-López, who works at the department of Environmental Science at Radboud University in Nijmegen, the Netherlands. She cooperated with researchers from the Netherlands Environmental Assessment Agency (PBL), the universities of Wageningen and Utrecht in the Netherlands and a colleague from the School of Life Sciences, University of Sussex.

Higher hunting pressure around villages and roads

'There are several drivers of animal decline in tropical landscapes: habitat destruction, overhunting, fragmentation etcetera. While deforestation and habitat loss can be monitored using remote sensing, hunting can only be tracked on the ground. We wanted to find a systematic and consistent way to estimate the impact of hunting across the tropics. As a starting point, we used the hypothesis that humans gather resources in a circle around their village and in the proximity of roads. As such, hunting pressure is higher in the proximity of villages and other access points. From there the densities of species increase up to a distance where no effect of hunting is observed. We called this species depletion distances which we quantified in our analysis. This allowed us to map hunting-induced declines across the tropics for the first time,' Benítez-López explains.

Not only the big cuddly species

The main novelty of the current study is that it combined the evidence across many local studies, thus for the first time providing an overarching picture of the magnitude of the impact across a large number of species. The study takes all animals into account -- not only the big cuddly species, but birds and rodents as well. Benítez-López explains the difference in impact between birds and mammals: 'Mammals are more sought after because they're bigger and provide more food. They are worth a longer trip. The bigger the mammal, the further a hunter would walk to catch it.' With increasing wild meat demand for rural and urban supply, hunters have harvested the larger species almost to extinction in the proximity of the villages and they must travel further distances to hunt. Besides, for commercially interesting species such as elephants and gorillas, hunting distances are much larger because the returns are higher.

Protected areas are no safe haven

Another interesting finding of this study is that mammal populations have also been reduced by hunting even within protected areas. 'Strategies to sustainably manage wild meat hunting in both protected and unprotected tropical ecosystems are urgently needed to avoid further defaunation,' she says. 'This includes monitoring hunting activities by increasing anti-poaching patrols and controlling overexploitation via law enforcement'.

Source: Radboud University Nijmegen [April 13, 2017]

byUnknown

in Endangered Species, Natural Heritage, Wildlife

April 13, 2017

Hunting accounts for massive declines in tropical animal populations

Hunting is a major threat to wildlife particularly in tropical regions, but a systematic large-scale estimate of hunting-induced declines of...

Read More

X-ray scanning immortalizes endangered primates in the digital afterlife, in 3-D

If you're a medical student, obtaining a human cadaver for learning anatomy or practicing surgical techniques is relatively easy. Thousands of people donate their bodies to science each year. But if you study and care for endangered primates, it's a different story.

Skimmer, a pygmy slow loris, was 19 when she died at the Duke Lemur Center in 2013. She is one of more than 100 
rare or endangered primates whose bodies are being preserved with help from an X-ray imaging technique 
called micro-computed tomography [Credit: Duke University]

Almost all of the roughly 100 species of lemurs are facing extinction in the wild due to logging, mining, hunting and slash-and-burn agriculture. Which is why, when an animal at the Duke Lemur Center dies from illness, injury or old age, a licensed veterinarian performs a postmortem exam within 24 hours of death, organs are removed, and tissue samples are collected so that other researchers can make use of them.

Cadavers of each species are stored in freezers or preserved in formalin—not for ghoulish curiosity, but so that years from now their bodies could be still be used for research and education.

And though these animals are gone, their bodies are now being preserved for present and future generations with help from an X-ray imaging technique called micro-computed tomography (microCT).

Soon, anyone will be able to go online to MorphoSource.org and get 3-D views of the internal anatomy of dozens of lemurs and other rare and endangered prosimian primates, in micrometer detail, without disturbing the original specimens.

"Even when they've passed, these animals continue to contribute valuable scientific data," said former Duke graduate student Gabe Yapuncich, who has been leading the effort to scan the specimens with Duke assistant professor Doug Boyer.

Yapuncich got the idea for the project while earning his doctorate in evolutionary anthropology. He was scanning the skeletal remains of present-day primates to see if certain foot bone measurements could help to reconstruct how much their extinct relatives might have weighed.

Researchers can learn about many aspects of primate biology from fossils, but most fossil specimens consist of isolated teeth or fragments of bones. Complete or even partial skeletons are rare.

"It seemed like a waste just to scan the foot and send it back," Yapuncich said. "Once I had a specimen on loan, I tended to scan the whole thing."

Virtual Dissection: No Scalpel, No Forceps

Yapuncich demonstrated how the technology works at Duke's Shared Materials Instrumentation Facility. On the ground floor of the Fitzpatrick Building stands a giant lead-lined box, installed in 2013 with startup funds from Boyer, which looks like an airport security scanner.

Inside, a Styrofoam cooler filled with dry ice contains the frozen remains of Beauty, a female bamboo lemur that died in 1985.

The microCT scanner blasts a cone-shaped beam of X-rays at the cooler as it spins slowly on a rotating platform. The X-rays that pass through Beauty's body hit a detector on the back wall, which records a snapshot.

The scanner takes thousands of snapshots for each full rotation. The data are sent to a computer, which uses the images to reconstruct two-dimensional cross sections of Beauty's insides, and these are stacked like slices of bread into a 3-D model.

Former Duke graduate student Gabe Yapuncich and assistant professor of evolutionary anthropology Doug Boyer 
are making 3-D X-ray scans of dozens of lemurs and other rare and endangered primates 
[Credit: Photos by Megan Mendenhall; design by Jon Fuller]

Yapuncich peers at the result on a nearby computer screen. It's a 3-D close-up of Beauty's head built from 1,900 cross-sectional images.

With the click of a mouse, he digitally dissects away Beauty's fur, skin and soft tissue to reveal the skeleton underneath in stunning, three-dimensional detail. He can also look at any 2-D slice to see internal structures in cross section.

The Duke Lemur Center is committed to studying lemurs without harming them. Imaging cadavers makes it possible to perform "virtual" dissections that would never be allowed on living animals.

With standard microCT researchers can visualize hard tissues such as bones and teeth, but by using special iodine-based stains, they can also see soft tissues such as muscles, nerves and blood vessels in the deceased animals.

Yapuncich has scanned the remains of more than 100 animals so far. A fat-tailed dwarf lemur named Jonas is one of them. When he died in 2015 at age 29, suffering from cataracts and other signs of age, he was the oldest of his kind. The scan shows his tail curled around his body, the roughly two dozen tail bones neatly lined up one after the other. "If you go to a museum collection, the tail vertebrae are just a bunch of bones in a box," Yapuncich said.

The Duke Lemur Center has housed and bred more than 4,000 endangered primates in its 50-year history. During that time, more than 400 cadavers from three dozen species of lemurs, lorises, galagos and tarsiers have been preserved for study.

The center fields dozens of cadaver requests from researchers each year. But these rare and fragile specimens can only be examined so many times using traditional methods. Repeated shipping and handling may expose them to damage and freeze-thaw cycles that would inevitably speed their decay.

By creating high resolution 3-D scans and putting them online, researchers hope to reduce destructive sampling and insure the availability of specimens for future study.

"There aren't that many available," said Duke R&D engineer and microCT specialist Justin Gladman. "If one researcher dissects and destroys one, the next researcher can't do anything with it."

"By scanning them in the microCT and creating these beautiful 3-D models, we can digitize the specimens and share them online," Gladman said. "Instead of being locked in a museum drawer, they're freely available."

Good from Tragedy

In the digital afterlife, Merlin's bony appendages are no longer nimble but still intact.

He was one of four of the fewer than 60 endangered aye-ayes living in captivity worldwide that died suddenly over 36 hours at the Duke Lemur Center in October 2016. Staff and researchers were devastated.

The culprit, tests later revealed, was a natural toxin found in avocados, not previously known to be harmful to lemurs, which damaged their heart muscles.

In assistant professor Doug Boyer's lab on Science Drive, recent Duke graduate Darbi Griffith uses software to stitch together nearly 3,000 2-D images of Merlin into a 3-D rendering.

Merlin was very popular with lemur center staff, and often enjoyed using his incredibly slender and dexterous middle finger to gently tease mealworms from his keepers' closed fists.

The 3-D volume rendering shows his body cloaked in skin and muscle. With a click his flesh fades away, and Griffith can zoom in on Merlin's skull to examine the complex wear patterns on his teeth, or peer inside his cranial cavity to estimate the size and shape of his brain.

Griffith has uploaded these 3-D images to an online database Boyer created called MorphoSource. Because the digitization is ongoing the Lemur Center scans haven't been made publicly available yet, but when they are, visitors to MorphoSource will be able to compare Merlin to other individuals, or measure anatomical variation across species.

Anyone will be able to browse the specimens, measure them, download the raw data and even create their own 3-D lemur models, both of bodies and skeletons, on a 3-D printer.

"It's the largest collection of 3-D lemur scans. That's pretty cool," Griffith said.

Source: Duke University [April 12, 2017]

byUnknown

in Endangered Species, Natural Heritage, Wildlife

April 12, 2017

X-ray scanning immortalizes endangered primates in the digital afterlife, in 3-D

If you're a medical student, obtaining a human cadaver for learning anatomy or practicing surgical techniques is relatively easy. Thousa...

Read More

Antarctic penguin colony repeatedly decimated by volcanic eruptions

One of the largest colonies of gentoo penguins in Antarctica was decimated by volcanic eruptions several times during the last 7,000 years according to a new study. An international team of researchers, led by British Antarctic Survey (BAS), studied ancient penguin guano and found the colony came close to extinction several times due to ash fall from the nearby Deception Island volcano. Their results are published in Nature Communications.

Gentoo penguins climbing slopes to the nesting colony on Ardley Island 
[Credit: Stephen Roberts]

Ardley Island, near the Antarctic Peninsula, is currently home to a population of around 5,000 pairs of gentoo penguins. Using new chemical analyses of penguin guano extracted in sediment cores from a lake on the island, the researchers unraveled the history of the penguin colony.

Climate conditions around Ardley Island have been generally favourable for penguins over the last 7,000 years and the team had expected the local population to show minor fluctuations in response to changes in climate or sea ice. The surprising result was that the nearby Deception Island volcano had a far greater impact than originally anticipated.

Lead author Dr Steve Roberts from BAS says: "When we first examined the sediment cores we were struck by the intense smell of the guano in some layers and we could also clearly see the volcanic ash layers from nearby Deception Island. By measuring the sediment chemistry, we were able to estimate the population numbers throughout the period and see how penguins were affected by the eruptions.

Volcanic ash layers in lake sediment cores extracted from Kiteschee Lake on Fildes Peninsula. The ash layers shown are 
associated with comparatively small eruptions from Deception Island in the last c. 2000-3000 years. The largest 
eruptions preserved in our lake sediment records from Fildes Peninsula and Ardley Island occurred at c. 7,000 years 
ago and c. 5,500-4,500 years ago and deposited over a metre of airfall and reworked ash in some lake sediment cores 
[Credit: Stephen Roberts and Emma Pearson]

On at least three occasions during the past 7,000 years, the penguin population was similar in magnitude to today, but was almost completely wiped out locally after each of three large volcanic eruptions. It took, on average, between 400 and 800 years for it to re-establish itself sustainably."

Dr Claire Waluda, penguin ecologist from BAS says: "This study reveals the severe impact volcanic eruptions can have on penguins, and just how difficult it can be for a colony to fully recover. An eruption can bury penguin chicks in abrasive and toxic ash, and whilst the adults can swim away, the chicks may be too young to survive in the freezing waters. Suitable nesting sites can also be buried, and may remain uninhabitable for hundreds of years."

The techniques developed in this study will help scientists to reconstruct past changes in colony size and potentially predict how other penguin populations may be affected elsewhere. For example, the chinstrap penguins on Zavodovski Island, which were disturbed by eruptions from the Mt Curry volcano in 2016.

Waluda continues: "Changes in penguin populations on the Antarctic Peninsula have been linked to climate variability and sea-ice changes, but the potentially devastating long-term impact of volcanic activity has not previously been considered."

Source: British Antarctic Survey [April 11, 2017]

byUnknown

in Antarctic, Earth Science, Ecosystems, Natural Heritage, Wildlife

April 11, 2017

Antarctic penguin colony repeatedly decimated by volcanic eruptions

One of the largest colonies of gentoo penguins in Antarctica was decimated by volcanic eruptions several times during the last 7,000 years a...

Read More

Food webs entangle humans in complex relationships with animals, crops and the environment

Reconstructed food webs from the Ancestral Puebloan southwestern United States show the complexity and interconnectedness of humans, other animals, crops and the environment, in an area of uncertain climate and resources, according to researchers, who think climate change and human decisions then, may shed light on future human choices.

Square Tower House in Mesa Verde National Park [Credit: Nate Crabtree]

"As southwestern archaeologists, we know that Ancestral Puebloan people were intrinsically connected to the environment," said Stefani Crabtree, postdoctoral fellow in human behavioral ecology in the Department of Anthropology, Penn State. "But, most food webs have omitted humans."

Traditionally, food webs, while they map the interaction of all the animals and plants in an area, usually do not emphasize the human component. Crabtree and colleagues created a digital food web that captures all categories of consumers and consumed, can be defined for specific time periods and can also represent food webs after major food sources or predators disappear from the area. If an area suddenly becomes devoid of deer or humans or corn, for example, a food web of that situation can show where predators went to find prey, or which prey thrived for lack of a predator.

These knockout food webs -- webs missing a specific predator or prey -- show the changes and pressures on the food sources substituted for the missing ones, or the changes that occur when pressure is removed by removing a major consumer. The researchers report the results of their study in the Journal of Archaeological Science.

"When people show up in the area around A.D. 600 they bring corn," said Crabtree. "It takes a while for critters to get used to it, but eventually, everything that eats vegetation, eats corn and prefers it."

Humans bringing corn into an area is a major disruption of the existing food web. Planting corn means clearing fields to displace whatever plants and animals were there, creating a high-energy plant source of food and switching plant eaters to the preferred higher-calorie food source.

In the American Southwest, the Ancestral Puebloan people eventually preyed on their deer population enough so that they deer were no longer a reliable source of food. To compensate for this, they began to domesticate turkeys for food. Turkeys need to be fed corn if they are captive and that competes with corn for human consumption. At this time, corn made up 70 to 80 percent of Ancestral Puebloans' food and so feeding turkeys altered the food web.

A sample food web with red nodes representing primary producers, orange nodes primary consumers, yellow-orange 
nodes omnivores, true-yellow nodes are true carnivores. This draft food web was created with the program 
Network3D from foodwebs.org [Credit: Stefani Crabtree, Penn State]

To create the food web, the team identified all the common, noninvasive species in the area. They then added species that were found in archaeological sites, but were absent from the modern lists. In some food webs, components are identified by their function, so all humming birds are considered flying pollinators, but in this case each type of humming bird received its own place in the web, linked to what it ate and what, if anything, ate it. This produced a very complicated web, but supplied exceptional redundancy.

"In the insect world it is harder to get at the data," said Crabtree. "We have not been able to get at good databases so we aggregate at the functional level -- pollinators or bloodsuckers for example."

The exception to individual web entries then are invertebrates -- insects, spiders, snails, etc. -- that were classified by their function. Invertebrates are organized to the level of order and then grouped by function. With insects, for example, the researchers would group butterflies and moths that pollinated and sipped nectar, together in one group.

The overall food web had 334 nodes representing species or order-level functional groups with 11,344 links between predator and prey.

The researchers realize that there are differences in the environment between now and the Ancestral Puebloan period, but many things, such as pinon-juniper woodlands and sage flats are the same. Enough similarity exists for this approach to work.

The team did not produce just one overall food web, but also food webs corresponding to three archaeological locations and three time periods of Ancestral Pueblo occupation in the area -- Grass Mesa Pueblo for Pueblo I, Albert Porter Pueblo for Pueblo II and Sand Canyon Pueblo for Pueblo III. They began with using archaeological assemblages from these sites incorporating all human prey and all human predators into the food web. Then they included the prey of the primary prey of humans and then predators of these human-prey species. Prey, in this case, includes animals, insects and plants.

A coyote preying on an entire clutch of baby rabbits in Boulder County, CO. [Credit: Mindy Wilkinson]

When creating knockout food webs, the researchers included only those species that were found in reasonable quantities in the archaeological assemblages at those times.

"Knockout food webs are one of the best ways to understand how people interact with the environment," said Crabtree. "Because we can remove something, predator or prey, and see what would happen."

When major changes in climate variables such as drought, heat and lack of snowpack are factored in, the balance in the food web may become unstable. When food becomes scarce, most mobile creatures, animals and insects move to another location. During the time of the Ancestral Puebloans, this was possible and eventually, these people moved to the area of the Rio Grande in New Mexico and other places in New Mexico and Arizona.

"We didn't have a long-term plan during the 600 years of Ancestral Pueblo habitation in the Mesa Verde region," said Crabtree. "We don't have a long-term plan today either. We don't even have a four-year plan. Some people are pushing us to look closely at climate change."

In the past, people migrated, said Crabtree. Unless we figure out better strategies, where are we going to migrate out to? We do not have a place to go, she said.

What people plant and eat has a great effect on the environment and on ecosystems. In the end, those choices will impact human survival, according to the researchers.

This work is part of a collaboration of researchers creating resolved food webs from a variety of places. Crabtree believes that she can compare this project to others that include humans in other geographical areas to help understand ecosystems with humans in them.

Author: A'ndrea Elyse Messer | Source: Penn State University [April 10, 2017]

byUnknown

in Americas, Archaeology, Climate Change, Ecosystems, Environment, North America, USA, Wildlife

April 10, 2017

Food webs entangle humans in complex relationships with animals, crops and the environment

Reconstructed food webs from the Ancestral Puebloan southwestern United States show the complexity and interconnectedness of humans, other a...

Read More