Estimation of fat sand rat Psammomys obesus abundance by using surface indices

The fat sand rat Psammomys obesus Cretzschmar, 1828 is an important reservoir host for the human disease, cutaneous leishmaniasis. To develop a method for monitoring changes in the population density of this rodent over large areas, fragments of food, faeces, urine marks, and earth mounds at the burrow entrance were evaluated as indicators of abundance. The results were compared with population density measured simultaneously by trapping. Through the year as a whole, urine maths correlate poorly with abundance, but the three other indicators correlate well. A correlation coefficient of 0.74 is achieved with food fragments and faeces combined. The correlation is best during the wet season and poorer in dry conditions. The value of this indirect population index is discussed in relation to climatic conditions. Details are proposed for the establishment of a monitoring system for P. obesus populations in time and space.