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In the framework of available historical data on population size and human impact on the Asian elephant Elephas maximus Linnaeus, 1758, we developed a stochastic simulation model for elephant populations, which simulates individual elephants and includes their geno- and phenotype regarding the tusk character. The model omits density dependence of reproduction parameters and mortality rates. The model predicts female mortality and mean calving interval to be the paramount factors determining the long-term population trend. For simulated female mortality rates of 5% and 5.5% a mean calving interval of 5.2 years and 4.4-4.5 years, respectively, leads to stable populations, which is in accordance with values derived from field observations. Taking into account a higher mortality of tuskers due to human impact, frequencies of the tusk allele were simulated both for dominant and recessive inheritance of the tusk character. The best accordance with census data was achieved, when the tusk allele was assumed to be dominant, combined with a slight reproductive advantage for tuskers. Since the model simulates population dynamics and tusk allele frequencies under various mortality schedules, it can be used to predict the effect of conservation efforts on populations of the Asian elephant.
In Asian elephant Elephas maximus Linnaeus, 1758 tuskless bulls or maknas are generally rare. Only in Sri Lanka 93% of subadult and adult bulls have been reported to be maknas. Using historical records and computer simulations we demonstrate that this situation is man-made. The following mechanisms were identified to be associated with a loss of tuskers: (1) When using elephants, man has always preferred tuskers. (2) Selective hunting and capturing frequently led to a decrease of tuskers in wildliving populations. (3) The impact of selective hunting and capturing was highest in isolated populations, such as Sri Lanka. (4) Selective removal of tuskers for protecting a maximum wild-living male population resulted in an increase of maknas. The rate of increase in the frequencies of maknas in particular populations with known history could be best explained by a dominant mode of inheritance of tusks in combination with a slight advantage of tuskers in reproduction. For the mainland populations it can be predicted that even in those where tuskers are already largely lacking the allele responsible for the expression of tusks should often be sufficiently abundant to allow the recovery of tusk bearing males.
Elephants were confined to Mengyang Protected Area in China and their distribution range had reduced greatly compared to past records. A preliminary study of habitat selection by Asian elephantsElephas maximus Linnaeus, 1758 and their distribution was conducted in Mengyang Protected Area and its surrounds using site visits and transect surveys from July 2003 to December 2006. Although no variable significantly influenced their habitat selection, elephants still showed preference for altitudes between 900 and 1200 m, gradients <30°, and orientations to the south-east, south and south-west. Human activities, including habitat transformation and degradation, disturbance by large infrastructure and poaching were considered to be the main factors inducing elephant distribution changes.
Owing to landclearing and human expansion, Asian elephantElephas maximus Linnaeus, 1758 is declining throughout its range. In lowland Nepal, the species now only occurs in small remnant populations, shared with India. In order to develop guidelines for conserving the species in the country, we studied the habitat use of a small and recently re-established population in Bardia National Park. We used the distribution of dung in fixed width transects to estimate seasonal habitat selection at a general scale of the Park. We also analyzed a specific habitat selection by elephants within the sal-dominated forest, by comparing the composition of trees and frequency of previous elephant impact on them along fresh tracks with those at random points. Elephants strongly preferred floodplain communities both during the cool and the hot season, but there was a marked shift from forest to grass-dominated subtypes between these seasons. Within the sal-dominated forest, there were more trees with previous elephant impact and a higher density of important food trees, especiallyMallotus phillippinensis along fresh tracks than in random points. We found little if any effect of human activity or location of available water on the spatial distribution of elephant dung. The density of the colonizing population was low (ca 0.2 animals/km2), but numbers are expected to increase in the future. With the preferred floodplain habitat being quite small (ca 60 km2), animals are then expected to spread outside the national park. A large tract of government forest adjacent to the park may then, for some time, provide needed space for the expanding population.
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