1. In vertebrate population estimation, converting faecal density into animal density requires information on the 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.2. 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. The total and age-specific elephant density based on dung bolus diameter was 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 the 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 structure assessment and its limitations were evaluated.3. The mean defecation rate was 13.51 ± 0.51 per day. The defecation rate was significantly lower for the younger age class and increased with the age of elephants.Defecation rates were significantly lower in the wet season than in the dry. The dung bolus diameter positively increased with the age of elephants, and the growth curve can be used to predict the age and age structure of elephant populations.4. The disparity in the dung production rate results in the lower availability of younger age class (juvenile and calf) dung in the transect for counting, which results in lower dung abundance. The detection probability of dung piles of younger age classes was low (0.58). The survival rates of dung piles of younger age classes were lower and increased with the age of elephants in the wet season. Hence, the demographic assessment of the population based on dung needs to consider age-specific differences in dung production, decay and detection probability. Although the This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

The various components of the dung count method of population estimation were evaluated such as defecation rate, decay rate, detection probability of dung and age-specific estimates of elephant density based on dung size. The defecation rate of elephants was determined in captive elephants of the Mudumalai elephant camp, Tamil Nadu, India. A total of 14 elephants in the dry season (Dec-Mar 2002) and 17 elephants in the wet season (Jun-Oct 2007) of different age-sex classes were observed for 42 days and 51 days by focal sampling methods and circumference of largest dung pile were measured to determine the growth curve. Total and age-specific elephant density based on dung circumference were estimated using indirect dung count method, 24 transect lines of 2 ~ 4km resulting in a total of 125km distance in Mudumalai Tiger Reserve. The dung decay rate was determined by marking fresh dung piles (n = 1628) every month with an average of 125 ± 77 dung piles/month from Jan 2007 to Feb 2008. The mean defecation rate was 13.51±0.51 (n = 94) per day. The defecation rate varied across age-sex classes and seasons with a lower defecation rate for younger age classes. The dung circumference measurements showed similar growth curves to other Asian and African elephants. Dung size-based age classification significantly overestimates the adult age class, giving an estimate of 82% adults in the population against the true 48.5%. Experimental analysis of detection of dung across perpendicular distance detection of larger and smaller dung size/age classes is equal at a visible distance and declined significantly for younger age/size class at the furthest distance. Decay rate varied significantly according to age classes and across seasons, with lower dung survival rates of younger age classes compared to adults. The minimum required sample size for the dung decay experiment was 250. The age-specific estimate of elephant density based on the indirect dung count method revealed a precise estimate on density, both decay and defecation contribute less than 12% of the variance of the estimate. Age composition based on dung count is highly skewed towards adults, younger age class were low due to lower defecation and faster decay and lower probability of detection in the transect.

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Human-elephant conflict (HEC) is a negative interaction between elephants and humans. HEC affects local community livelihood and the success of elephant conservation. The Asian elephant population and HEC were studied in the Niligiri Biosphere Reserve in the year 1992 (Balasubramanian et al. 1995) using this information as baseline data. We have studied HEC in the selected 14 villages located in the Moist Deciduous forest and Thorn forest areas of Mudumalai Tiger Reserve from Nov 2006 to Mar 2008, which were part of the earlier study. The data on crop species, elephant damages, protection method and land-use changes concerning HEC were collected fortnightly by direct enumeration and questionnaire survey. A total of 297 crop damage incidences were recorded. The crop-raiding pattern and the peaks in raiding are during monsoon periods were similar to the earlier study. A total of seven people were killed and six were injured by the attack of elephants in the ten years (1998 to 2008) and results in 1.3 incidences/year. The overall crop damage has declined from 2.1% in the early 1990s to 0.98%. The spatial location of HEC indicated that the mean damage percent was higher in the peripheral areas (1.51%) than in the center of the village (0.18%). There is a major shift from crops grown for food (finger millet) to commercial reasons. Multiple regression analysis revealed that the effective perimeter length (perimeter with cultivation) and total area of cultivation had a primary influence on the crop damage, followed by the area of degradation around the village and percent edible crops in the boundary. Further, logistic regression on crop-raiding incidences with the independent predictors indicated that among habitats in the MDF the crop-raiding incidences were 95% higher than that of TF. Palatable crop species plantain, paddy, finger millet and vegetable crops were 391% raided more frequently than the non-palatable species. Crops with protection methods were 22% less frequently damaged than the crops without any protection. Thus changes in the crop species, improved protection and land-use changes have reduced HEC in the adjacent areas of Mudumalai TR. The resettlement of villages from the core area of reserve in MDF would greatly reduce HEC in MTR.

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