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

New animal species now official when published online

The International Commission for Zoological Nomenclature (ICZN), the body that regulates animal species names, took a big step earlier this week when it announced that electronic publication of a new species name is now sufficient to make that name official.

Prior to the announcement, the ICZN code stated that a new species name only became official once it was printed. The stipulation was intended to ensure that records of species names were securely archived and would remain accessible over the long term, but for an online-only publisher like PLOS, it meant that we had to print and store physical copies of each paper describing a new species in addition to our standard online publication. To put this in perspective, PLOS ONE published 25 papers presenting new animal species in 2011, and has already published 32 in 2012, including the tiny Brookesia chameleons pictured at the top of this post, so this additional printing and archiving is not trivial.

Now, though, the Commission has decided to adjust their standards in response to today’s increasingly electronic environment. According to the ICZN press release about the updated rules, the change “is intended to speed the process of publishing biodiversity information, to improve access to this information, and to help reduce the ‘taxonomic impediment’ that hinders our cataloguing of the living world.”

It won’t be a free-for-all: new species names must be published in journals or books with ISSNs or ISBNs, so purely web options like blogs or Wikipedia are not sufficient, and before publication authors must register their name with ZooBank, the official ICZN online registry for scientific names of animals. Overall, though, the hope is to reduce the barriers to proper nomenclature monitoring and archiving. The updated code is also in line with similar recent changes to the regulations for naming new botanical species.

The update is part of a broader discussion around how to ensure long-term reliability and durability for any type of electronic records, and while this problem may not yet be robustly solved, we at PLOS ONE applaud the ICZN’s efforts to address the changing needs of today’s scientists.

Image citation: Glaw F, Köhler J, Townsend TM, Vences M (2012) Rivaling the World’s Smallest Reptiles: Discovery of Miniaturized and Microendemic New Species of Leaf Chameleons (Brookesia) from Northern Madagascar. PLoS ONE 7(2): e31314. doi:10.1371/journal.pone.0031314