The zip file on this page contains the "dunsurv" program designed to estimate animal abundance.  It uses results of a survey for dung density combined with observations of the decay state, on the day of the survey, of a number of dung samples known to be fresh on a series of dates preceding the date of the survey.  The user is required to supply an estimate of defecation rate.  Further documentation and an example file are included in the zip file.