Identifying Fecal Groups by pH Analysis

The pH values of 50 fecal groups, of varying weathering ages up to 6 months, for both mule deer (Odocoileus hemionus) and pronghorns (Antilocapra americana) were determined with a Hach DR Colorimeter, graduated pH paper, and a 605 HT Pocket Comparator. There was no overlap between the pH ranges of the two species when the pellets were crushed and analyzed with the colorimeter. This method of identification was completely accurate for the two species on the Fort Stanton Experimental Range. A reliable method for identifying fecal pellets of mule deer and pronghorns is necessary for the accurate census of mule deer by the pellet-group-transect method in areas where both species occur and overlap in their ranges. External appearance of the pellets often gives the careful observer a clue to the origin of the group, but appearance is by no means accurate because of the wide range of sizes and shapes that occur within the pellet groups of each species (Smith 1964:436). Because of the error that can arise from external examination, a more precise method for identification was investigated.