Age-specific differences in Asian Elephant defecation, dung decay, detection and their implication for dung count

In vertebrate population estimation, converting faecal density into animal density requires information on faecal production rate, decay rate, and faecal density.  Differences in the above factors for long-lived species across age classes were not evaluated.  We have evaluated these factors associated with the dung count of Asian elephants (Elephas maximus) in the tropical forest of Southern India.   
The defecation rate of elephants was determined in semi-wild elephants at the Mudumalai elephant camp. The relationship between dung bolus diameter and age was determined to estimate the age of the elephant. Total and age-specific elephant density based on dung bolus diameter were estimated. A total of 24 transect lines of 2-4 km (125 km) were sampled in the study area. An experiment was conducted to assess detection probability across the age classes of dung piles. The dung decay rates across age classes and seasons were determined by marking fresh dung piles (n=1551). The dung-based age...