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panda approaching feeder How do giant pandas find their food? That's one question that Lorie Tarou, Research Assistant for Giant Panda Behavior Studies, wanted to answer. It may sound simple, but because of the pandas' unique categorization as an herbivorous carnivore, the usual assumptions about foraging are impossible to make. Herbivores can often return to certain spots to find food sources, and have adapted with good spatial orientation and memory for foraging. The skills that a carnivore uses to hunt prey, like keen eyesight, smell, or speed are quite different. So where does a bamboo-eating bear fit into the equation? And how does a panda decide where to forage?

Lorriane Tarou putting food in a feederAfter their yards were set up with a series of feeders, (food bowls with hinged lids containing food or left empty) Mei Xiang and Tian Tian were released one at a time into a yard and given the opportunity to discover and consume any food they can find in the strategically placed feeders.

Over time, the patterns shifted and new variables were added to to the feeders. Lorie observed how fast Mei and Tian adapted to the challenges by measuring what food they found and ate, and what they left behind. Not only was she able to learn about foraging skills, but perhaps more fascinating, whether they used their eyes, noses, spatial awareness or a combination of their abilities to do so. This study was also conducted with pandas at Zoo Atlanta and the San Diego Zoo.

We learned that our pandas were very efficient foragers.

FeederExploratory Phase

Phase I

In this first phase, the pandas had 15 minutes to find biscuits inside eight feeders, which were arranged in a circle. We looked at the pattern the pandas followed to visit the baited feeders and the number of times they revisited depleted or empty feeders. Going back to a feeder that a panda had already depleted of food would not be considered very efficient foraging because it would waste energy. Following the path of the circle to visit each adjacent feeder is considered the most efficient way to complete the task. Criss-crossing is less efficient.

The key to efficient foraging is using as little energy as possible, while consuming as much energy (food) as possible. This is the basis of what scientists call "optimal foraging theory" and testing this theory involves determining how animals decide where to forage, when to forage, what food to eat, and how long to stay in the place they found their food.

Finding Food with Visual Cues

Phase II

Giant pandas Mei Xiang and Tian Tian, now in the second phase of the foraging skills study, are being tested to determine their ability to use visual cues to locate food. Lorie Tarou, National Zoo research assistant, at right, sets up the experiment each morning before letting Mei and Tian out in their yards to forage from the available options.

Of the eight feeders that will be in the panda's yard, four feeders with black lids will contain food, while feeders with white-colored lids will be empty. Black was chosen because it is unknown if pandas are able to see in color. In this phase of the experiment, researchers hope to learn whether pandas have the ability to associate the appearance of the feeders with the presence of food.

In this task, efficient foraging required the panda to learn to visit feeders with black lids first.

Finding Food by Association

Phase III

How good are you at finding food? You might answer, “It depends where I am!” If you’re on vacation in a new place and get hungry, you know that looking for a restaurant is probably going to get you fed a lot quicker than looking for a hardware store.

Likewise, if you’re home, the kitchen would be the first place you’d look for food, not a bedroom or a bathroom. Because we make a connection between food and the places we found or ate food before, we associate food with kitchens, refrigerators, supermarkets, and restaurants.

Part of this study would determine if giant pandas find food this way, too. People know surprisingly little about what strategies giant pandas use to locate their main food source, bamboo. The giant panda is a solitary animal that lives in forests and is rarely seen in the wild, so it is very hard to study how they forage. That’s one reason they are being studied here at the Zoo.

Insight into the way giant pandas obtain food is considered an important key to helping the species survive in the wild.

The Logistics of Testing Pandas

This phase, called the “Spatial Cue Use” portion of the foraging study, was the third of five different phases. In this phase, both giant pandas were given the opportunity to find food in eight baited feeders for 15 consecutive days.

Each lid-covered feeder was in a fixed location in the panda’s outdoor yard. The same four feeders were filled with food everyday while the other four will be consistently left empty.

If researchers were designing this experiment for people, they’d put eight small refrigerators in your kitchen. Every morning before you came out of your room, they would put a snack inside the same four refrigerators everyday. After a few days, you would probably start checking the ones with the snack inside before you bothered with the ones that you remembered were always empty. The sooner you caught onto this pattern, the better the scientists would say you were able to find food. The same goes for the giant pandas in this experiment.

How quickly and how often pandas find and eat biscuits from the four feeders that have food, and skip over the other four empty feeders helped reveal how good they are at finding food. This information provides valuable information about how location cues factor into giant panda foraging.