logo_nopix_sm.gif (467 bytes)   behave_title_white.gif (1132 bytes)

  Behavioral Education for Human, Animal,
Vegetation & Ecosystem Management

Stories of Applied Animal Behavior
Created by members of a graduate Foraging Ecology Class
     at the University of Idaho and Washington State University
     under the direction of Drs. Karen Launchbaugh and Lisa Shipley

How Do Pygme Rabbits Forage?
A Close Look at Central Place Foraging


By Becky Elias


Pygmy rabbits (Brachylagus idahoensis) are an important animal that we know little about. They are a small North American rabbit that eats primarily sagebrush (Artemisia tridentata). In the state of Washington, there is a population of pygmy rabbits that are genetically different from the other populations of pygmy rabbits. These rabbits, called the Columbia Basin pygmy rabbits, have become endangered due to habitat loss and other reasons. Currently, the Columbia Basin pygmy rabbits are being bred in captivity to build up a population for release into the wild. It is important for us to learn about the behavior of these animals while they are in captivity, so that we can apply this knowledge when they are released back into the wild and improve their chances of survival.
One thing that we need to know is what these rabbits eat and how they forage. We know that a pygmy rabbit's diet is made up of more than 99% sagebrush in the winter and their summer diet is mostly sagebrush and other available greens. Pygmy rabbits live and forage in a patchy sagebrush habitat and forage out from their burrow. Pygmy rabbits are a prey species to many animals such as coyotes and raptors, and they have a high risk of predation while they are foraging. If pygmy rabbits live in a patchy, open environment and have a high risk of predation, then how do they forage to reduce these risks? One theory is that they are "central-place foragers".

Central-Place Foraging

There are many definitions of central-place foraging, but it can generally be thought of as an animal foraging out from a central location that they use as a refuge, and bringing some food back to this refuge and consuming it there. This method of foraging is very costly to the animal. Not only does the animal have to go out and find food, but they have to drag the food back to their central location to consume it. This requires the animal to expend a lot of extra time and energy. Pygmy rabbits seem to use the central-place foraging method as their strategy for foraging. Pygmy rabbits have a burrow as their central location, and they move out from this burrow to forage for food. They are often seen dragging food items back to the entrance of their burrow and consuming it there. If central-place foraging is so costly to the animal, then why would the pygmy rabbits choose this foraging strategy? The answer can be found in the major benefit of central-place foraging; a reduced risk of predation to the foraging animal. If the animal consumes the food in a protected location, they spend less time avoiding predators out in the open. This allows the animal using the central-place foraging strategy to devote less time to vigilance while foraging. Since pygmy rabbits have a great risk of predation, it would be greatly beneficial for them to choose this foraging strategy. It seems that the reduced predation benefit the pygmy rabbits receive for using central-place foraging is able to compensate for the high costs occurred from this foraging strategy.

Learned or Innate Behavior

We also need to know if central-place foraging is a learned or an innate behavior. Because this strategy of foraging is a predator avoidance behavior, we might assume it is an innate behavior, since behaviors that can have deadly consequences if done incorrectly are often innate. Also, the pygmy rabbits are generally solitary animals and spend little time with their mothers as young, so they would have little opportunity to learn the central-place foraging behavior from another rabbit. However, central-place foraging is a fairly involved behavior and may need to be perfected over time to perform it correctly. This contradicts the idea that central-place foraging is an innate behavior, and indicates the behavior might be learned. Actually, central-place foraging is probably a combination of learned and innate behaviors. The general use of the behavior as a means to avoid predators is most likely an innate behavior. However, because of its complexity, rabbits probably individually learn over time how to perfect this foraging strategy to best suit their needs. For example, the pygmy rabbit may instinctively know to run when it sees a predator approaching, but may learn with time where optimal foraging places are, with sufficient amounts of cover.

Management Implications

So now we know how pygmy rabbits forage and why they do so. How will this aid us in the recovery of the endangered Columbia Basin pygmy rabbit? This knowledge of their foraging strategy can help us to choose their release site when rabbits are reintroduced into the wild. We can choose release sites that provide the rabbits with enough cover to evade predators and enough food to satisfy their needs. This ideal release site will be around soil that is easy for the rabbits to dig in and has abundant sagebrush for cover and food. Choosing the ideal release sites for these rabbits upon their reintroduction, will aid the rabbits in their survival, and provide them with a chance for a successful recovery.

Suggested Readings:

Orians, G.J. and N.E. Pearson. 1979. On the theory of central place foraging.
    An Analysis of Ecological Systems: 155-177. Horn, D.J. and R.D. Mitchell
    (Eds.). Columbus: Ohio State University Press.

Elliott, P.F. 1988. Foraging behavior of a central-place forager: field tests of
    Theoretical predictions. American Naturalist 131:59-174.

Back to Index Page

Learn more about the Foraging Ecology Class by visiting http://www.cnr.uidaho.edu/range556/