Populations of cave invertebrates are generally considered to be food-limited. The cave entrance is a major source of food input into the community in the form of decaying organic matter. Thus, the densities of scavenging terrestrial cave invertebrates should be related to the distance from the cave entrance because this represents a measure of food abundance. A test showed this expectation to be true in Crossings Cave, Alabama. A population density peak occurred 10 m inside the cave where the dark zone and detritus infall regions meet. The greatest population peak occurred at 100 m where densities of crickets and their guano are highest. The pattern should hold for most caves, but the actual distances will vary in each site depending on its circumstances. When the fauna was removed from the cave, the remnant had not regained community equilibrium a year later. Removal of the dominant scavenger, a milliped, allowed other species populations to expand because of decreased competitions.
Peck, Stewart B..
The effect of cave entrances on the distribution of cave-inhabiting terrestrial arthropods.
International Journal of Speleology,
Available at: http://scholarcommons.usf.edu/ijs/vol8/iss4/1