Observations on the Dambuilding Behavior of the Beaver (Castor Fiber L.)

摘要

The experiments seem to indicate that the stimulus-situation which regulates the dam-building activities is comparatively simple. It seems to be clear that the dam building activity is released by acoustical stimuli from water running swiftly over the dam and by optical stimuli from indentations in the top of the dam. Optical stimuli from indentations in the up-stream side of the dam also release the pushing of material to the dam in the same way, as indentations round the lodge or tunnels release the lodge building activity. On the contrary, in the experiments the animals did not react to optical stimuli from water running over the dam or to any kind of stimuli from water being sucked through holes in the upstream side of the dam under the surface. If the water was running very swiftly over the dam the animals were building intensely on the dam at especially high water level, as well as at especially low water level. It then seems as if the water level has no direct effect on the dam building behaviour. On the contrary, a rising water level seems to have a releasing and stimulating effect on the lodge-building activity. (Author)