Elephant Dung Piles Research Articles

Recent estimate of Asian elephants in Borneo reveals a smaller population

Asian elephants occurring in northern Borneo form a geographically isolated and genetically distinct population. Of this, the subpopulation of Central Sabah holds the greatest opportunity for long‐term survival, due to a relatively large population size and occurrence over a vast, contiguous and protected habitat. We surveyed this subpopulation in 2015 using advanced methods to obtain a population size estimate. We used the distance‐sampling framework and laid out transects following a stratified random design for counting elephant dung piles; measured dung decay following the ‘retrospective' method; and used Bayesian analysis to estimate dung decay rate and dung pile density. Thus, we estimated a posterior mean dung decay rate of 212 days (95% BCI: 133–319), an overall elephant density of 0.07 per km2(95% BCI: 0.03–0.11) and a population size of 387 elephants (95% BCI: 169–621). These estimates were far lower than the population size of 1132 individuals and density of 1.18 per km2estimated in 2008. It is unlikely that there has been a steep population decline, as there were no drastic land‐use changes between 2008 and 2015, nor were there other identifiable causes for a population decline. Therefore, it appears that the methodological and analytical flaws in the previous estimate are the most plausible reason for this observed difference. Given that the new estimate suggests a much smaller population, it is prudent and precautionary to use the new estimate as the basis for all policy decisions and conservation actions for elephants in Sabah.

Population characteristics and habitat suitability of Asian elephants (Elephas maximus Linnaeus, 1758) in the Khao Yai National Park, Thailand

Abstract The aim of this study was to investigate the population and habitat of wild elephants in the Khao Yai National Park, to provide elephant population densities using the line transect method. Habitat suitability was also assessed based on the data obtained from the location of the species during monthly ranger patrol across the park area, with the rate of dung decay used for population calculation. The population structure and age class were studied by direct observation to estimate the population trend. On the basis of 116 systematic transect lines that were 2 km in length and separated by 500-m intervals, a total of 1,209 elephant dung piles were found in more than 213.20 km. The analysis of the combined data showed that the dung density was 531.49 dung piles/km2, with a decay rate of 0.0039 dung piles/day based on 56 dung piles checked every 7 days. The annual data showed that the population density was 0.15 individuals/km2. The population structure comprising calf:juvenile:subadult:adult was 1: 1.09:1.14:2.10; the sex ratio of adult male to adult female elephants was 1:1.10; and the ratio of reproductive ability among adult females, juveniles, and calves was 1.00:0.99:0.90. The combined data also showed that the main environmental factor affecting the presence of the animals was salt lick sites. The pooled data analysis found that the habitat most suitable for the elephants covered an area of 220.59 km2. The habitat suitability, based on the dry season appearance data, covered an area of 258.64 km2, whereas during the wet season, it covered an area of 517.45 km2. As the most suitable habitat for elephants appears around the park boundary, habitat improvements for wild elephants should address the central areas of the national park. A greater emphasis should be placed on creating salt licks, being far from human activity sites.

Frugivory and seed dispersal by the Asian Elephant Elephas maximus in the tropical forests of Nilgiri Biosphere Reserve, southern India

Seed dispersal plays a potential role in plant species demographic processes. Elephants are important seed-dispersing agents. We studied frugivory and seed dispersal by Asian Elephants in the tropical deciduous and thorn forests of the Nilgiri Biosphere Reserve, southern India. We determined fruit consumption based on the presence of seeds and fruit remnants in elephant dung piles. In total, we identified seeds of eight plant species belonging to seven families in 16% out of 455 dung piles examined between 1991 and 2004. Coinciding with a peak fruiting season in the study area, seeds and other fruit parts appeared in the dung piles significantly more frequently during the dry season than in the wet seasons (southwest and northeast monsoons). Owing to differences in fruit species abundance in different habitats, there was more evidence of fruit consumption in the dry thorn than in the dry and moist deciduous forests. This corresponds with insufficient grass availability in thorn forests during the dry season and an increase in browse consumption as a supplementary diet. Seeds of Tamarindus indica and Acacia intsia were found in elephant dung more frequently than other species. Seed and fruit remnants were found in almost an equal number of dung piles of both bulls and herds.

Predictive mapping of season distributions of large mammals using GIS: an application to elephants on Mount Kenya

Summary 1. Knowledge of elephants in forested environments where visibility is poor is often restricted to elephant density estimates derived from counts of elephant dung piles along line transects. Elephant dung piles are a good indicator of elephant habitat use over a period of time (i.e. a season) because they remain visible for several months. Using Mount Kenya (MK) in Kenya as a case study, we demonstrate how those dung pile counts can additionally be used to develop elephant dung pile explanatory models and distribution maps. 2. The dung pile explanatory models are built from a selected number of line‐transect samples per season using generalized linear model analysis, in which the counted dung of each sample is explained by the combined effects of a series of environmental and anthropomorphic parameters. For the significant explanatory parameters in the models, digital map layers are developed and integrated into a geographic information system. Applying the explanatory models, predictive seasonal elephant dung pile distribution maps are developed. 3. Data preparation and analysis are intensive, but the distribution maps derived from explanatory parameters of distribution are a powerful tool for patrol planning and land‐use management and to locate areas of high elephant density and the habitats they move between. This method is useful for sites where physical, environmental, logistical or other constraints render it impossible to spread line transects evenly over the entire study area, assuming that transects are representative samples of the entire habitat.

Forest Elephants: Tree Planters of the Congo

ABSTRACTThe abundance of large vertebrates is rapidly declining, particularly in the tropics where over‐hunting has left many forests structurally intact but devoid of large animals. An urgent question then, is whether these ‘empty’ forests can sustain their biodiversity without large vertebrates. Here we examine the role of forest elephant (Loxodonta africana cyclotis) seed dispersal in maintaining the community structure of trees in the Ndoki Forest, northern Congo. Analysis of 855 elephant dung piles suggested that forest elephants disperse more intact seeds than any other species or genus of large vertebrate in African forests, while GPS telemetry data showed that forest elephants regularly disperse seeds over unprecedented distances compared to other dispersers. Our analysis of the spatial distribution of trees from a sample of 5667 individuals showed that dispersal mechanism was tightly correlated with the scale of spatial aggregation. Increasing amounts of elephant seed dispersal was associated with decreasing aggregation. At distances of<200 m, trees whose seeds are dispersed only by elephants were less aggregated than the random expectation, suggesting Janzen–Connell effects on seed/seedling mortality. At the landscape scale, seed dispersal mode predicted the rate at which local tree community similarity decayed in space. Our results suggest that the loss of forest elephants (and other large‐bodied dispersers) may lead to a wave of recruitment failure among animal‐dispersed tree species, and favor regeneration of the species‐poor abiotically dispersed guild of trees.

Shit Happens (to be Useful)! Use of Elephant Dung as Habitat by Amphibians

ABSTRACTAlthough elephants are commonly cited as an example of ecosystem engineering, cases involving Asian elephants are missing in the literature. In a dry environment of southeastern Sri Lanka, I examined 290 elephant dung piles and found a total of six frogs from three different species in 1.7 percent (N=5) of the dung piles. This suggests a facilitative role of elephants by providing habitat for amphibians.

The survival of elephant dung piles in relation to forest canopy and slope in southern Ghana

The survival of elephant dung piles in relation to forest canopy and slope in southern Ghana

Rate of decay of elephant dung in the central sector of Parc National des Virunga, Democratic Republic of Congo

"This article focuses on the dung decay analysis undertaken in January-May 1999 as a follow up to the April-July 1998 study of the status and population estimate of elephants in the central part of Virunga NP. (Mubalama 2000) Excessive growth of Acacia sps and bush invasion into savannah areas as a result of the large scale loss of elephants in the 1970s-1980s disallowed easy observation in this area so researchers chose assess the utility dung counts. This study assesses the decay of dung in this area. During both research periods a sample set of fresh elephant dung piles was monitored at 14 day intervals. It is considered that the length and seasonal timing of the study periods provide sufficient information to assess dung counts in this area in both the wet and the dry seasons. The latter time allowed for dung piles to be observed from the time they were fresh until they decomposed and dissappeared. Decomposition is principally brought about by three factors: dung beetles, termites and mechanical disturbances such as heavy rain, fire, trampling and foraging for insects by birds."

Diet and distribution of elephant in the Maputo Elephant Reserve, Mozambique

The distribution and diet of the elephants of the Maputo Elephant Reserve were studied using dung counts, satellite tracking and faecal analysis. The results were compared with earlier data from before the civil war in Mozambique. The elephant population decreased during the civil war, but 180 animals still remain. Earlier studies described the elephants as preferring the grass plains. Currently, the elephants prefer the dense forest patches over the high quality forage found in the grass plains. Water salinity affected distribution; elephant dung piles were found closer to fresh water in the dry season. A total of 95 different plant species were identified in the faeces. The percentage of grass was relatively low compared with other studies, increasing at the beginning of the rainy season. At the end of the dry season, elephants concentrated on the few available browse species with young leaves, but generally preferred grass species to browse species. Diet composition was mainly affected by season and less by habitat. The elephants have changed their habitat preference in reaction to poaching, and probably increased the contribution of browse species in the diet. The presence of forest patches has been vital for the survival of the elephants.

Seed dispersal of Acacia erioloba by African bush elephants in Hwange National Park, Zimbabwe

Approximately two‐thirds (64%) of all dry season samples of elephant dung analysed during a 3‐year study in the Main Camp subregion of Hwange National Park, Zimbabwe, contained seed and/or pod materials from Acacia erioloba. Most seeds were recovered intact and actively germinating seeds were not uncommon. Very little pod mass relative to seed mass was recovered in most instances, with pod fragments recorded from only 56% of all exhaustively sampled elephant dung piles containing A. erioloba fruit materials. Nonetheless, large pod fragments and even entire intact pods were recovered occasionally from elephant dung. Seeds and pods of A. erioloba may comprise 12% or more of total wet‐weight dung mass; individual dung piles were found which contained > 5000 A. erioloba seeds. Birds and smaller mammals search out and consume A. erioloba seeds present within elephant dung piles. The findings of this study indicate that potential digestibility of A. erioloba seeds for bush elephants (Loxodonta africana africana) may be much higher than expected from previous studies. In controlled feeding trials with captive bush elephants (age 11–15 years old) maintained on predominantly free‐range dry season diets, the estimated efficiency of digestion for A. erioloba seeds consumed in pods was 81% to 96%, with a gut‐transit time of between 24.5 and 36.0 h. On the basis of throughput times determined in experimental feeding trials, potential elephant‐dispersal distances of 20–50 km are predicted for A. erioloba in the Kalahari Sands landscapes of southern central Africa.

Estimating Forest Elephant Numbers with Dung Counts and a Geographic Information System

Dung counts are the most practical means of estimating numbers and distribution of forest-dwelling elephants. In the forests of Gabon, which have a sparse human population, the density of elephant dung piles increased with distance from roads. Human influences (roads and density of human habitation) accounted for half the variation in dung-pile density. Ninety-five percent of the dung piles were estimated to occur in the low human density stratum that covers two-thirds of Gabon. We present a new method of estimating the dung-pile population using the gradient of dung density in relation to roads. Estimates of the gradient were combined with estimates from a geographic information system (GIS) of the area of forest in bands at different distances (e.g., 0-5, 5-10 km) from roads. This process gave an estimate of the dung-pile population for the whole forest zone; the standard error and confidence limits were found by bootstrapping. We argue that estimates of forest elephant abundance in central Africa will be both more accurate and more precise if one accounts for the gradient. Simulation showed that the optimum sample for Gabon is 40 transects, each 5 km in length.

Factors affecting the duration of elephant dung piles in rain forest in the Lopé Reserve, Gabon

SummaryA sample of 1282 fresh elephant dung piles was monitored regularly in rain forest in the Lopé Reserve, Gabon, over a two‐year period, and the time taken to reach Stage E of Barnes & Jensen (1987) was recorded. Statistically significant differences were found in mean duration of dung piles in different months. There were negative correlations between mean dung duration and both rainfall in the previous three months and mean humidity between 1300 h and 1500 h. However, the most important factor affecting dung duration was found to be fruit content of the diet in any given month.RésuméOn a contrôlé régulièrement un échantillonnage de 1282 excréments frais d'éléphants dans la forêt humide de la Réserve de Lope, au Gabon, pendant deux ans, et on a noté le temps nécessaire pour atteindre le stade E de Barnes & Jensen (1987). On a trouvé des différences statistiquement significatives de la durée moyenne au cours des différents mois. II y avait une corrélation négative entre la durée moyenne des excréments, et les chutes de pluie des trois mois précédents et le taux moyen d'humidité entre 13h et 15h. Cependant, on a trouvé que le facteur influencant le plus la durée des excréments était le contenu en fruits du régime alimentaire au cours des mois.

Estimating decay rates of elephant dung piles in forest

SummaryData from a dropping decay experiment were re‐analysed following the finding by other workers that decay is not an exponential process. Methods based on the assumption of constant age‐specific decay gave biased estimates of the mean decay rate for the population of droppings. The best estimate was obtained by weighting the decay rate by the frequency of droppings in each age‐class.RésuméOn a réanalysé les résultats d'une expérience sur la décomposition des excréments suite au fait que d'autres chercheurs avaient trouvé que la décomposition n'est pas un processus exponentiel. Les méthodes basées sur l'hypothèse d'une décomposition constante liée à l'âge donnent des estimations biaisées du taux moyen de décomposition pour l'ensemble des excréments. On a obtenu la meilleure estimation en mettant en balance le taux de décomposition et la fréquence des déjections pour chaque classe d'âge.