The Poop Will Tell Us: Do Elephants and Rhinos Compete for Food?


A recent study of the two animals in Addo Elephant National Park, called “Shift in Black Rhinoceros Diet in the Presence of Elephant: Evidence for Competition?” suggests the answer is yes.

Scientists interested in helping endangered species like the African elephant and the black rhinoceros would like to know whether these animals compete for resources in the wild, as such food contests could impact the population and health of both species. Unfortunately, our favorite rough-skinned big guys have IUCN statuses of vulnerable and critically endangered, respectively, so competition for food between them may present a bit of an ecological puzzle.

To gain evidence of food competition, researchers from Australia and the Centre for African Conservation Ecology took a close look at elephant and rhino poop (no, seriously) across different seasons to identify the types of plants each herbivore  was eating. Poop collecting was performed at times of the year when rhinos and elephants ate in the same region, and then again when only rhinos grazed in the area (in the absence of elephants). Variations in the plant types found in the feces were counted as indicators of dietary differences.

While it’s been shown that the presence of elephants can help some herbivores with habitat and food access, limited studies have been conducted on how the elephants’ foraging behavior may affect that of specifically megaherbivores. The authors state that there is clear evidence that elephants hog and monopolize food, a behavior that they suspected would affect the diets of other large herbivores. Indeed, the results of this study revealed that resource use was clearly separated by season, and rhinos munched on different grasses depending on whether or not the elephants were present. Without elephants around, rhinos ate more diverse plants, like woody shrubs and succulents, but in their presence, rhinos restrained themselves and consumed more grasses. This may not seem like a big deal, but rhinos are known to be strict browsers (read: picky about their food choices), so this dietary difference discovery was surprising to researchers.


The authors go on to suggest that elephants living at high population densities in certain regions may significantly affect the foraging opportunities of other grazers, and these close living quarters may have long-term effects on the overall fitness of the other animals. These behaviors may have particularly important consequences in smaller or fenced-in wildlife parks, where populations tend to grow at the same time that food availability goes down.

Citation: Landman M, Schoeman DS, Kerley GIH (2013) Shift in Black Rhinoceros Diet in the Presence of Elephant: Evidence for Competition? PLoS ONE 8(7): e69771. doi:10.1371/journal.pone.0069771

Image Credits: African wildlife photo by Chris Eason (Mister E); plot from article

It’s for the birds: Citizen science reveals shift in winter bird homes

western grebe 2

Just in time for summer solstice (the longest day of the year!), we bring you the heartwarming tale of a study that analyzed data collected about our feathery friends in the middle of winter. The Audobon Christmas Bird Count, a yearly bird census originating back in 1900, is conducted by bird-loving volunteers all over the Western Hemisphere who spot birds and record their sightings. It is also an example of what some call “citizen” or “crowd-sourced” science, and a newly published PLOS ONE article demonstrates how this scientific data, collected by the general public, can help researchers assess the conservation needs of an at-risk migratory bird, the western grebe.

Canadian researchers wanted to take a closer look at the bird population patterns of the grebe, a marine water bird that had recently been showing a worrying trend of drastic population declines in its winter home, ranging from the Pacific coast to California. In “Citizen Science Reveals an Extensive Shift in the Winter Distribution of Migratory Western Grebes,” researchers modeled a whoppin’ 36 years of collected bird count data from 163 “circles,” or designated diameters of land, mounting to a total of 2.5 million grebe observations.

So, what did they—and we, in this case—find? Thanks to decades of data collected by birdwatchers (1975-2010), researchers were able to show that western grebe populations along the northern Pacific coastal region decreased by about 95% over 36 years, but increased by over 300% in coastal California. Similar trends were observed for related bird species, suggesting that the winter habitat of the grebe has shifted south by ~ 900 km, to California, between 1980 and 2010.

western grebe 3

This is much better news than finding a concerning population decline that might prompt time-consuming and expensive conservation efforts. The researchers state that they aren’t yet sure of the reasons for this shift, but they suspect that the types of fish prey the grebes feed on may have also shifted in abundance between the two locations. All in all, this study demonstrates that wildlife data gathered by the general public (in any season, really) can result in meaningful, published scientific research that is useful to ecologists and conservationists alike.

Citation: Wilson S, Anderson EM, Wilson ASG, Bertram DF, Arcese P (2013) Citizen Science Reveals an Extensive Shift in the Winter Distribution of Migratory Western Grebes. PLoS ONE 8(6): e65408. doi:10.1371/journal.pone.0065408

Image Credits: Grebe photo by Mike Baird; map photo from article


Sharing was Caring for Ancient Humans and Their Prehistoric Pups

huskies_1While the tale of how man’s best friend came to be (i.e., domestication) is still slowly unfolding, a recently published study in PLOS ONE may provide a little context—or justification?—for dog lovers everywhere. It turns out that even thousands of years ago, humans loved to share food with, play with, and dress up their furry friends.

In the study titled “Burying Dogs in Ancient Cis-Baikal, Siberia: Temporal Trends and Relationships with Human Diet and Subsistence Practices,” biologists, anthropologists, and archaeologists joined forces to investigate the nature of the ancient human-dog relationship by analyzing previously excavated canid remains worldwide, with a large portion of specimens in modern-day Eastern Siberia, Russia. The authors performed genetic analysis and skull comparisons to establish that the canid specimens were most likely dogs, not wolves, which was an unsurprising but important distinction when investigating the human-canine bond. The canid skulls from the Cis-Baikal region most closely resembled large Siberian huskies, or sled dogs. Radiocarbon dating from previous studies also provided information regarding the dates of death and other contextual information at the burial sites.

The researchers found that the dogs buried in Siberia, many during the Early Neolithic period 7,000-8,000 years ago, were only found at burial sites shared with foraging humans. Dogs were found buried in resting positions, or immediately next to humans at these sites, and their graves often included various items or tools seemingly meant for the dogs. One dog in particular was adorned with a red deer tooth necklace around its neck and deer remnants by its side, and another was buried with what appears to be a pebble or toy in its mouth.

prehistoric dog_3

By analyzing the carbon and nitrogen in human and dog specimens in this region, the researchers were able to determine similarities in human and dog diets, both of which were rich in fish. This finding may be somewhat surprising because one might assume that dogs helped humans hunt terrestrial game, and would consequently be less likely found among humans that ate primarily fish.

The authors speculate that dogs were considered spiritually similar to humans, and were therefore buried at the same time in the same graves. The nature of the burials and the similarities in diet also point toward an intimate and personal relationship, both emotional and social, between humans and their dogs—one that involved sharing food and giving dogs the same burial rites as the humans they lived among. Ancient dogs weren’t just work animals or hunters, the authors suggest, but important companion animals and friends as well.

Citation: Losey RJ, Garvie-Lok S, Leonard JA, Katzenberg MA, Germonpré M, et al. (2013) Burying Dogs in Ancient Cis-Baikal, Siberia: Temporal Trends and Relationships with Human Diet and Subsistence Practices. PLoS ONE 8(5): e63740. doi:10.1371/journal.pone.0063740

Image Credits: Losey RJ, Garvie-Lok S, Leonard JA, Katzenberg MA, Germonpré M, et al. (2013) Burying Dogs in Ancient Cis-Baikal, Siberia: Temporal Trends and Relationships with Human Diet and Subsistence Practices. PLoS ONE 8(5): e63740. doi:10.1371/journal.pone.0063740

Siberian husky photo by Pixel Spit

Some Like it Hot: Sick House Flies Purposely Induce a Fever

house fly

Fevers are thoroughly unpleasant and usually accompanied by other troublesome physical symptoms. Even so, they are often a good sign that our immune system is kicking in to help us “fight off” a nasty infection. Outside the world of endotherms (those of us that regulate our own body temperatures), some ectotherms—those that must seek heat to keep warm—also make use of fevers by finding a heat source to purposely induce them, a phenomenon known as a behavioral fever.

You might wonder why any creature, great or small, would choose to have a fever. One possible reason may be remarkably similar to the reason for fevers in humans: they help fight infections. If you weren’t aware of the massive insect-fungi war taking place right under our noses, the Cornell University Mushroom Blog says it all. In short, fungi have a terrible habit of infecting and killing all kinds of insects, and the insects’ best weapon of defense is to run to the warmest place possible. Make no mistake: the fever is not fun for the flies, and there are health risks and costs (like elevated metabolism and possible organ failure) the longer the fever is maintained. Nevertheless, it’s their best option.

In a recently published PLOS ONE paper, aptly titled “Discriminating Fever Behavior in House Flies, researchers at Penn State investigated this phenomenon further by testing whether house flies self-induced a behavioral fever in a dose-responsive manner to fungal infection. Fungus-infected flies were placed in boxes with temperature gradients (ranging from 77 to a balmy 102 degrees Fahrenheit), and their behavior was monitored throughout the course of the day.

Early in the morning, when the fungus had been actively growing all night, the flies hung out longer in the warmest parts of the box. As the flies’ increased body temperatures began to inhibit fungal growth, the flies would move to cooler areas; however, at night, the fungus would again begin to grow unabated, and the cycle would repeat. Interestingly, it was found that the higher the fungal dose, the higher the temperature of the induced fever. The researchers acknowledge that more work needs to be done, and other factors may contribute to the flies’ preference for heat. Nonetheless, this study underlines the importance and effectiveness of temperature regulation for suppressing infection in a surprising variety of species.

Citation: Anderson RD, Blanford S, Jenkins NE, Thomas MB (2013) Discriminating Fever Behavior in House Flies. PLoS ONE 8(4): e62269. doi:10.1371/journal.pone.0062269

Image Credit: Public domain

PLOS makes its first appearance at ACS!

bioinorganicCalling all chemists! PLOS ONE is headed to New Orleans next week for the American Chemical Society’s National Spring Meeting, where the theme is “Chemistry of Energy & Food.” ACS, the world’s largest scientific society, will be hosting more than 10,000 attendees who will gather to discuss all things chemistry, with a special emphasis on exploring chemistry’s relationship to food. In particular, the technical program will include talks and presentations covering sustainability, human health, food and energy biosystems, and the relationship between food and fuel.

Whether your field is biological, environmental, synthetic, or physical, PLOS ONE is looking to mingle with its authors, reviewers, and editors. If you’re in the neighborhood, please drop by and say hello! The PLOS ONE team will be at booth #1046 from April 7th through the 11th (Sunday to Thursday) to chat about and show our love for the science of matter.

If you’ve published in PLOS ONE, let us show you our article-level metrics and find out how many times your work has been cited, viewed, or downloaded as a pdf.

If you’re thinking about publishing with us, or are just new to open access and PLOS ONE, please pay us a visit and ask the ONE staff any burning questions you have about our policies and publication criteria. PLOS ONE has published over 14,000 research articles related to chemistry, and we are very excited to meet potential editors and reviewers with chemistry expertise.

Hope to see you soon!

Image Citation:

Weber E, Guth C, Weiss IM (2012) GFP Facilitates Native Purification of Recombinant Perlucin Derivatives and Delays the Precipitation of Calcium Carbonate. PLoS ONE 7(10): e46653. doi:10.1371/journal.pone.0046653

Dressed-Up Donkey Discovered at Religious Burial Site

Even in bygone eras, domestic animals were essential for the development of human civilization. Aside from their use as a primary food source, animals served as companions, hunters, protectors, and workers. However, they also participated in rituals and religious ceremonies, sometimes even deserving their own burials (animal mummies!). By analyzing the remains at discovered animal burial sites, archaeologists can learn a lot about human society during a specific era.

In a recently published PLOS ONE paper titled “Symbolic Metal Bit and Saddlebag Fastenings in a Middle Bronze Age Donkey Burial,” researchers describe the unprecedented discovery of a ritualized donkey burial, where the donkey had both a metal horse bit in its mouth and saddlebag fastenings on its back. Researchers determined that the donkey was carefully placed in the particular position, with limbs bent, as shown above, evidence of a purposeful burial. This specimen was dated to the Middle Bronze Age III (that’s roughly 1700/1650-1550 BCE) and found in a religious precinct at Tel Haror, an archaeological site in Israel.

This find is exciting because it indicates early use of harnessing/bridling equipment and a significant technological advance over using neck ropes, rings, or nose bands for steering pack animals. Through different types of analysis, the researchers shed light on the functional and symbolic roles of the donkey. Most notably, it appears that the burial and tacking were largely symbolic (nonfunctional) and part of a ceremonial ritual, which may have been followed by a feast involving other animals, whose bones were found nearby.

The researchers reached this conclusion based on a few key pieces of evidence. Dental analysis revealed that the donkey was sacrificed at a young age, about four years old. No wearing was evident on the teeth, meaning that it was probably never trained as a draught animal. In addition, the metal horse bit seems to have been pieced together, defective, and missing any adjoining bridle components when it was placed in the donkey’s mouth, suggesting that it would not have been used for actual labor. Finally, the saddlebags were smaller than usual; the researchers suspect that they were made specifically for the burial.

Understanding how humans utilized equid pack animals, especially donkeys, is important for identifying social, economic, and technological developments during earlier eras. In this case, it seems that the donkey’s role was largely one of high symbolic value, rather than functional, which may be related to the high social status that was attached to owning and riding donkeys at the time.

Citation and Images:

Bar-Oz G, Nahshoni P, Motro H, Oren ED (2013) Symbolic Metal Bit and Saddlebag Fastenings in a Middle Bronze Age Donkey Burial. PLoS ONE 8(3): e58648. doi:10.1371/journal.pone.0058648

Animal Heartbreakers? Animals, Behavior, and “Love”

Animal emotion remains a fairly contentious area of scientific research, but there is a growing body of evidence to support the idea that nonhuman animals can have feelings. The scientific community may not be ready to use the “L” word for animals, but we are beginning to understand that they do form relationships that are both more complex and insightful than they initially appeared.

While the birds and the bees don’t pre-order roses online or bust out heart-shaped boxes of chocolate for Valentine’s Day, many animal species—yes, even insects and spiders—exhibit courtship behavior to woo their mates (singing mice, anyone?). On the opposite end of the spectrum, animals can also be sneaky and engage in promiscuous behavior that rivals the latest plotline from your favorite soap opera. The physical, chemical, mental, and emotional drivers behind these behaviors are still under active investigation by the scientific community, and we have a few handy examples published in PLOS ONE.

In “Heaven It’s My Wife! Male Canaries Conceal Extra-Pair Courtships but Increase Aggressions When Their Mate Watches,” male domestic canaries, known to be socially monogamous, altered their courtship behavior toward females depending on the audience. Males were generally more aggressive with females around than with males or no one present. Males also courted other females more if their mates weren’t around, which the authors suggested may imply that there are costs (“divorce”) associated with courting other females while a mate watches. Tsk, tsk.

While canaries may be coy, some of our closest relatives display some of the fiercest aggressive and competitive behavior. In the recently published “Till Death (Or an Intruder) Do Us Part: Intrasexual-Competition in a Monogamous Primate,” owl monkey pairs were broken up by intruding “floater” monkeys, which in some cases, resulted in serious consequences for the ousted monkey: disappearance or death. These breakups also had a negative effect on the reproductive success of both the male and female monkey in the pair. Lasting monogamous owl monkey couples produced 25% more offspring than monkeys with two or more partners.

Are animals always heartbreakers? In what researchers consider an act of monogamy, pair-bonded California mice in this study refrained from scent marking when given the opportunity. This may not seem like a proud display of love and loyalty, but in the animal kingdom, scent marking can be a form of advertising for new females. The researchers also found that virgin male mice still participated in scent-marking behavior, providing further evidence that the other animals’ restraint was related specifically to pair bonding.

Just as we see behavioral differences in the animal kingdom, there’s certainly a lot of variety in human love and relationships. Regardless, we’d like to wish you all a happy Valentine’s Day!


Hanson JL, Hurley LM (2012) Female Presence and Estrous State Influence Mouse Ultrasonic Courtship Vocalizations. PLoS ONE 7(7): e40782. doi:10.1371/journal.pone.0040782

Panksepp J (2011) Cross-Species Affective Neuroscience Decoding of the Primal Affective Experiences of Humans and Related Animals. PLoS ONE 6(9): e21236. doi:10.1371/journal.pone.0021236

Ung D, Amy M, Leboucher G (2011) Heaven It’s My Wife! Male Canaries Conceal Extra-Pair Courtships but Increase Aggressions When Their Mate Watches. PLoS ONE 6(8): e22686. doi:10.1371/journal.pone.0022686

Fernandez-Duque E, Huck M (2013) Till Death (Or an Intruder) Do Us Part: Intrasexual-Competition in a Monogamous Primate. PLoS ONE 8(1): e53724. doi:10.1371/journal.pone.0053724

Image credit:

Monkey image, M. Corley/Owl Monkey Project

Graph, PLOS ONE paper, doi:10.1371/journal.pone.0053724

The Downside of Sharing: Winter Bugs

Unfortunately, increasing numbers of us are experiencing this year’s particularly brutal seasonal flu (most frequently influenza A, subtype H3N2). The CDC’s latest FluView report and US map show that nearly all states have widespread outbreaks, and these reports don’t include the other winter illnesses that typically plague us, like the common cold, bronchitis, and pneumonia.

As we arm ourselves with flu shots, alcohol hand rub, tissues, and disinfecting wipes, these stats also remind us to please cover our mouths when coughing and sneezing, and to stay home if we feel even the mildest of sniffles coming on. Peak flu season is usually in January or February, and in the wake of this epidemic, we’d like to draw attention to our rapid-peer-review journal, PLOS Currents Influenza, which has an ongoing call for submissions in research related to the 2012-2013 seasonal influenza outbreak.

Now that you’ve triple-wiped down your keyboard, mouse, and phone, let’s have a look at some winter-illness-related research articles published in PLOS ONE within the past year.

Have you ever wondered why flu outbreaks always seem to occur during the winter months in the first place? A paper titled “Relationship between Humidity and Influenza A Viability in Droplets and Implications for Influenza’s Seasonality” may shed some light on the matter: listen to a featured podcast about this article in Scientific American, posted just last month. In this study, researchers investigated the relationship between humidity, a characteristic that can vary with temperature, and the viability and transmissibility of influenza A virus droplets. Researchers suspended the virus in different media and found that it didn’t survive as well when conditions were salty, or when the humidity was between 50 and 98%. However, the virus was extremely viable in mucus, and at conditions below 50% (dry) or above 98% (almost tropical), the virus was also quite viable and happy. The results of this research may explain why influenza outbreaks are prolific in both dry, cold weather as well as tropical environments.

For those of you that haven’t yet been convinced to run out and get a flu shot (cough, shown to be 60% effective, cough), you may be interested in a paper published last summer, showing that at least certain types of flu, like H1N1, may be transmitted before any clinical symptoms are noticeable. The study, “Transmission of a 2009 H1N1 Pandemic Influenza Virus Occurs before Fever Is Detected, in the Ferret Model,” finds that sick ferrets placed close to healthy ones could spread the flu by contact or droplet exposure a whole day before any clinical symptoms appeared. Interestingly, coughing and sneezing had less to do with transmission than did the viral concentration in the ferrets’ noses. Additionally, after day five or six of illness, viral transmission significantly decreased, supporting the idea that it may be safe to return to school or work after the worst of the illness has passed.

A recently published paper describes an investigation into the motivations behind Americans’ tendency to not get flu shots, a behavior that has been troubling and puzzling to both doctors and scientists alike. In “Behavioral Responses to Epidemics in an Online Experiment: Using Virtual Diseases to Study Human Behavior,” researchers created an “infectious disease outbreak” game in a virtual multiplayer online world to study how willing people were to protect themselves during epidemics. Players accumulated points depending on their health status and actions they took, but they needed to spend points to protect themselves and thereby reduce their chances of falling ill. Results indicated that a person was more willing to take self-protective action when the outbreak was severe, or when a prior experience with inaction had resulted in illness. Players were also more likely to take preventative measures if they were less costly, which indicated to researchers that decreasing the cost of the flu shot could ultimately decrease the overall prevalence of the disease.

These articles are just a tiny droplet in the bucket of influenza-related research published in PLOS ONE. Click here to read more research articles on one of the more common types of seasonal flu, the influenza A virus.

And, please stay safe and healthy in these remaining winter months!

Image credit:  the H3N2 virus, ID#13470, CDC


Yang W, Elankumaran S, Marr LC (2012) Relationship between Humidity and Influenza A Viability in Droplets and Implications for Influenza’s Seasonality. PLoS ONE 7(10): e46789. doi:10.1371/journal.pone.0046789

Roberts KL, Shelton H, Stilwell P, Barclay WS (2012) Transmission of a 2009 H1N1 Pandemic Influenza Virus Occurs before Fever Is Detected, in the Ferret Model. PLoS ONE 7(8): e43303. doi:10.1371/journal.pone.0043303

Chen F, Griffith A, Cottrell A, Wong Y-L (2013) Behavioral Responses to Epidemics in an Online Experiment: Using Virtual Diseases to Study Human Behavior. PLoS ONE 8(1): e52814. doi:10.1371/journal.pone.0052814

A rockin’ good time at AGU

Last week the American Geophysical Union (AGU) Fall Meeting was held just down the road from our San Francisco office, and PLOS staff could not pass up the opportunity to make an appearance.

If you were an exhibition hall attendee and could manage to tear yourself away from all the talks, poster sessions, and workshops long enough to pay us a visit, you would have been met with friendly staff from both PLOS ONE and PLOS Currents Disasters, all on a mission to inform as many geophysicists as possible about open access and our various journals. We thoroughly enjoyed spending the week there and meeting any PLOS readers, authors, editors, and reviewers that stopped by to say hello. In particular, our publications manager Krista Hoff was excited to meet and have a chat with one of our longstanding Academic Editors, Ben Bond-Lamberty.

In an little bit of contrast to our recent visit to the Annual Meeting of the American Society of Human Genetics, many passersby did not immediately recognize the PLOS name. They were similarly unaware of our status as a nonprofit, our commitment to open access, and our relatively unique publication criteria. These conversations led to an exciting opportunity for us to explain that we publish in all areas of science, and especially to show our love to the worlds of geology, physics, chemistry, and environmental science.

While free pens were flying off the table, we had stimulating conversations with seismologists, planetary scientists, climatologists, geologists, and environmental scientists. Our rapid-peer-review journal PLOS Currents Disasters was extremely well-received among researchers associated with earthquakes or other chemical and geological hazards (including potential meteor disasters!).

Many scientists found our printed Open Access guide “How Open Is It?” both helpful and informative, and several were big proponents of open-access journals, excited to find that we accept submissions in geophysics research.

Long-time PLOS supporters were thrilled to inform us that they intended to submit at least one paper within the next year, and we definitely piqued the interest of at least a few potential reviewers and academic editors. We had some great discussions about barriers to scientific publishing in general and received insightful suggestions for improving the overall publication experience. We appreciated hearing everyone’s feedback and will be sure to incorporate your suggestions into our future discussions.

Look out for the PLOS booth again in just a few days at the American Society for Cell Biology, where we hope to see yet another side of our growing and diverse PLOS community!

Photo credits: U.S. Geological Survey Photographic Library