Least-Cost-Path analysis.

This applet (created by Michael Gilpin) demonstrates route-finding algorithms that have some applicablility to the way that animals may move through the environment. Each cell represents an area of habitat. As an animal moves it has choices to make.

• Each cell represents a "cost" to the animal.
• Low cost (light green) is good in terms of disturbance, stress, danger, energy expediture (as in finding food, security) etc.
• High cost (bright red) is bad;there are characteristics of that habitat that the animal will avoid if possible.

Try picking your own least cost path from the upper left corner to the lower right corner; click on each successive cell to trace a path and view your results to the right of the grid. Then let the computer do the same thing; choose Computer Solve.

{This java applet works best with newer versions of Navigator or Explorer; newer versions of Java; and of course with faster processors. For example, Navigator 3.0 on a 250MHz G3 Mac takes about 34 seconds to run the computer solve. Navigator 4.0 on a 266 PII:about 11 seconds to run, on a 400MHz PII: about 8 seconds . The animal solve program varies but is slightly faster than the 10,000 random paths on slower machines, and slower than computer solve on faster machines.}

This is the type of analysis that was used to find potential habitat connections between the protected core reserve areas in the U.S. Northern Rockies. However, this applet is somewhat more realistic. Typical least-cost-path algorithms find the shortest distance with the least cost so the overall cost is minimal. This is not necessarily the way an animal might choose; it doesn't know in many cases what the final goal (the end cell) is and makes it choices on more of a local basis. In this applet:

• Computer solve picks the least overall cost
• Animal solve picks a route based on local knowledge only
• Clicking from cell to cell is up to you; but you know what the final goal is

  However, animals are much more complex than simple computer models.

  Computer simulations like these are only the first step in identifying corridors for animal movements. These may provide a shortcut for where to look more closely on-the-ground. It is extremely important to examine each area closely, relate the habitat and topography to what you know about the behavior of the animals in question, and get the advice of local residents and professional biologists who know what areas are actually being used by animals.