Elephants, iconic for their size and intelligence, are herbivores with complex dietary needs and habits. While the basic fact that "elephants eat plants" is widely known, a deeper examination reveals a nuanced and fascinating world of foraging strategies, nutritional requirements, and ecological impacts. This article delves into the intricacies of the elephant diet, drawing upon recent research and established knowledge to provide a comprehensive understanding of what these magnificent creatures consume and how they obtain their sustenance.
Dietary Diversity: A Matter of Survival
To protect elephants and other major species and create environments in which they can successfully reproduce and grow their populations, they need a variety of plants to eat. Wildlife populations need access to diverse dietary resources to prosper. Elephants are generalist foragers, which means they feed on a wide variety of crops. As generalist foragers, they feed on a wide variety of crops. It’s really important for conservationists to keep in mind that when animals don’t get enough of the foods that they need, they may survive - but they may not prosper,” said study author Tyler Kartzinel, an assistant professor of environmental studies and of ecology, evolution and organismal biology at Brown.
Seasonal Shifts in Diet
Elephants primarily eat browse (trees and shrubs)-but switch to growing grasses and other plants when seasonally available. Their foraging choices also, in part, shaped by plant defenses. Studies have shown that elephants adjust their diets based on seasonal availability. During the wet season, when grasses are abundant, they consume a higher proportion of these. Conversely, in the dry season, when grasses become scarce, they shift to a higher proportion of woody plants. The simple answer is that elephants vary their diets based not only on what’s available but also their preferences and physiological needs, said Kartzinel.
Plant Variety and Selective Feeding
Elephants eat a wide variety of plant tissues-leaves, twigs, bark, forbs, herbs, roots, leaf-bearing shoots, and fruits. Populations potentially feed on hundreds of plant species. Despite this broad palette, elephants feed selectively, choosing specific plants based on their nutritional content and palatability. They use their excellent sense of smell to detect plant odors and can avoid ingesting plants (or parts of plants) they recognize to contain toxic compounds. Some savanna plants have spines, thorns, or dense branches that make browsing more difficult.
Nutritional Needs and Mineral Acquisition
Elephants seek out crops and tree bark with high amounts of energy or possibly for minerals. They also sometimes eat fruits from trees planted around villages. Mothers producing milk and sexually active males have higher nutritional needs. Elephants also seek out minerals (e.g., sodium, potassium, calcium) in water, soil, and even from cave walls. They lick soil near water sources or dig into banks and under trees. In some locations, savanna elephants ingest minerals from termite mounds. Minerals may improve nutrition, help digestion, or buffer toxic compounds that plants use in defense against herbivores. Also have saliva protein(s) that are thought to reduce the toxicity of tannins-plant compounds that could have harmful effects if consumed in large amounts.
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Foraging Strategies and Trunk Dexterity
A wild African elephant eats rapidly, consuming 190 grams of food a minute, to provide adequate fuel for its vast bulk. African elephants like the ones in this study have two muscular extensions at the tip of their trunk resembling a pair of fingers that also could be studied as models for future robotics. The elephant diet consists of large volumes of plant materials such as leaves, fruit and roots.
The Role of the Trunk
A human can pick up multiple objects at once by squeezing them together with both hands and arms. An African elephant also picks up many items at once but with only one appendage-its soft, heavy trunk. The elephant’s trunk is similar to other boneless organs in nature such as the octopus’s arm and the human tongue. But unlike an octopus’s arm, an elephant’s trunk is heavy enough to provide significant force on an object without muscular pressure. Flexible "fingers" at tip can pick up small food objects, individually and with precision. Foods and water also sucked into trunk using trunk muscles and lungs, which create a negative suction pressure.
Trunk Mechanics and Robotics
“They don’t just use the trunk’s strong muscles to squeeze the plants together,” said Hu. “The elephants also use the weight of the trunk, and they do that by forming a joint in the trunk. The African elephant can raise or lower the trunk joint’s height by up to 11 centimeters to increase or reduce the applied force. “When elephants need more force, the joint is higher up on the trunk,” Hu said. Elephant trunks weigh about 150 kilograms and have 40,000 muscles. This research could have applications in robotics, where heavier machines would appear to have few advantages over smaller ones. But, in the future, heavy robotic manipulators could be designed with several adjustable joints that use the device’s own weight to provide adjustable pressure and save energy. “You could have future robots with several joints, which could apply various weight pressures below joints to help compress objects together for lifting them efficiently,” said Hu. “This would allow you to use the weight of the joints themselves to provide force instead of relying on batteries and extra motors to apply these forces, and that would mean using less energy. For instance, you could have a heavy robot with four joints, and by bending the top joint, the weight below it could apply a load. If you wanted to provide less weight pressure, you could instead bend the second-from-the-top joint.
Manipulating the Environment
Elephants push trees over to expose roots or reach high branches in the canopy.
Water Consumption and Waste Elimination
Need to drink roughly 150 to 200 liters (40 to 50 gal) of water per day [savanna elephant]. Pouch at base of tongue (pharyngeal pouch) allows elephants to store up to several liters of water. Will drink once a day, when water available-but ranges of every 1 to 2 days, or 3 to 5 days, also reported. Will drink water with salt in it, if freshwater not available (can be fatal if salt content too high). Defecate as many as 10 to 20 times a day. Digestion time is about 40 hours [adult females]. The elephant dung was important to the ecosystem as a source of nutrition for other wildlife.
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Dietary Studies and Conservation Implications
PROVIDENCE, R.I. [Brown University] - Elephants eat plants. That’s common knowledge to biologists and animal-loving schoolchildren alike. A new study from a global team that included Brown conservation biologists used innovative methods to efficiently and precisely analyze the dietary habits of two groups of elephants in Kenya, down to the specific types of plants eaten by which animals in the group. In 2001 study author Thure Cerling and myself started collecting dung samples and hair tails from individual elephants in Samburu, northern Kenya, for a study into elephant seasonal diet changes and how they relate to migratory patterns. We chose members of the Royals and Artists family for our study. During our analysis we were able to show that elephants switched from eating fresh grasses when it rained to eating trees and bushes during the long dry season. Dung samples, like these, are loaded with data on what elephants eat. Through their detailed analysis, the team of researchers were able to discover that dietary differences among individual elephants are often far greater than had previously been assumed. They also learnt that elephants vary their diets based not only on what’s available, but also their preferences and physiological needs. The Brown University study, which was published this month in Royal Society Open Science showed surprising variation from meal to meal - even among family members that forage together. Last year, Save the Elephants, in conjunction with the Department of Biology at the University of Oxford, published a separate paper that also revealed fascinating facts about the dietary habits of African elephants.
Innovative Research Methods
The research group compared the new genetic technique to a method called stable isotope analysis, which involves a chemical analysis of animal hair. Two of the study authors, George Wittemyer at Colorado State University and Thure Cerling at the University of Utah, had previously shown that elephants switch from eating fresh grasses when it rains to eating trees during the long dry season. The scientists had saved fecal samples that had been collected in partnership with the non-profit organization Save the Elephants when Wittemyer and Cerling were conducting the stable isotopes analyses almost 20 years ago. The team coupled combined analyses of carbon stable isotopes from the feces and hair of elephants with dietary DNA metabarcoding, GPS-tracking and remote-sensing data to evaluate the dietary variation of individual elephants in two groups.
Individual Dietary Variation
They also learnt that elephants vary their diets based not only on what’s available, but also their preferences and physiological needs. The Brown University study, which was published this month in Royal Society Open Science showed surprising variation from meal to meal - even among family members that forage together.
Feeding in Captivity
To mimic the eating habits of an elephant in nature, here at Seneca Park Zoo, we create multiple feeding opportunities for the four African elephants. Each elephant consumes about 140 pounds of food in one day. That amount of food is broken down into three bales of hay, 10 pounds of fruits and vegetables, five pounds of elephant chow, and three pounds of bran twice a week. In order to provide the elephants with such a large amount of food in one day, we separate it into multiple feedings. Each elephant has a breakfast, bath, lunch, and dinner training routine at which time they will receive a combination of the elephant chow and some produce. Genny C and Lilac can also have up to five pounds of bagels for specific sessions like their baths. Moki and Chana can only have bagels on very special occasions because we are working towards getting them to a more sustainable, healthy weight. The training sessions provide mental and physical stimulation for the elephants, and they allow us to check over each elephant’s entire bodies every day. The elephants look forward to these sessions and the time with their keepers knowing the good treats they are going to get for them! Their hay is given in smaller amounts throughout the day to keep them grazing as they would in nature. We also have barrels and nets hanging up high around the habitat that we fill with their hay in order to mimic the experience of eating out of tall trees. It is also very important to provide the elephants with fresh browse, or vegetation like twigs or young shoots, as much as possible. Their favorites include sugar maple and willow branches. The elephants’ favorite food items include watermelon, pumpkins, and cabbage. Bagels and breads, although they can only be given under special circumstances, are also a huge favorite! We can also give the elephants small quantities of food enrichment items throughout the day. Examples include cereals, pretzels, oats, rice cakes, pastas, pancake mix, and canned vegetables.
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