A Method for Determining the Activity of Burrowing Mammals

Abstract

In connection with life history studies of burrowing rodents it has proven necessary to determine the extent of utilization of burrow systems in ground squirrel colonies. A simple, inexpensive technique was sought to measure which burrows or entrances to burrow systems were being utilized, as well as the time of utilization. The solution of the problem involved a small benzine lamp and sheets of coated paper. Both of these items are utilized in physiology laboratories for kymograph recordings. The paper is smoked in the field by holding desired lengths over the benzine lamp. The smoked paper is then rolled into a cylinder and inserted into the burrow entrance far enough to avoid its exposure to atmospheric moisture. The rolled paper can be stapled into a cylindrical form of desired size, but equally good results can be obtained by rolling the smoked paper into a cylinder slightly smaller than the burrow diameter and inserting it into the burrow entrance. Upon being released the paper springs open to form a tube completely surrounding the burrow passage. Periodic checks of the inserted papers show whether any animal has entered or left the burrow if footprints have been left on the smoky surface. Used papers can then be replaced to record activity for the following determined period. In addition to recording daily periodic use of burrows, longer time intervals can be employed in the absence of excess moisture as the smoked paper, particularly if previously waxed, stands up well under field conditions. This technique has proven valuable in determining the time of emergence of hibernating mammals as well as checking on their post-emergent activity.