Organisms that alter the physical structure of their environments are ecosystem engineers and they create new habitat that can be exploited by other species in multiple ways, beavers, termites, leaf cutter ants, and mud lobsters are all environmental engineers, as are earthworms that improve the environment for use by other species. Ransom (2011) experimented with earthworms and red-backed salamanders (Plethodon cinereus) in an effort to determine if salamanders use earthworm burrows, and if they do, to examine the influence earthworm burrow use has on the salamander's competition with other salamanders and their ability to survive predators. Ransom found red-back salamander used earthworm burrows 50% of the time when burrows were present. However, the slimy salamander, Plethodon glutinosus, did not use the worm burrows. When other slimy salamanders were present or the red-backed were alone they used cover objects 70% of the time instead of the worm burrows, when other red-backed salamanders were present P. cinereus used cover objects only 40% of the time. The presence of earthworms did not change the behavior of the red-backed salamanders. Earthworms reduced the leaf litter and the number of micro invertebrates but did not impact the mass of salamanders in the study area. Additional experiments suggest that the use of earthworm burrows allowed the red backed salamanders to escape predation from garter snakes (Thamnophis sirtalis) and increased their survival rate during the winter.
Ransom, T. S. 2011. The influence of habitat provisioning: use of earthworm burrows by the terrestrial salamander, Plethodon cinereus. Oecologia, 165: 745-754.