Tracking Silver Moon: What We Learned
Silver Moon's satellite collar functioned from December 2002 until the battery died in August 2004, eight months later than expected. During that time Silver Moon ranged over an area of 610 square kilometers (about 235 square miles)much larger than an earlier estimate of her home range (477 square kilometers, or 181 square miles) that was based on dung surveys. Because Silver Moon is a female, the data actually represent the movement of her whole herd. See animated map of movements.
In the first months of the study, home-range patterns indicated significant differences in space and habitat use between cool-dry, hot-dry, and rainy seasons, with the largest home ranges during the rainy season. See results shown in seasonal movement map.
Silver Moon was never located outside the boundary of Alaungdaw Kathapa National Park (AKNP), suggesting that the herd is restricted to the park. Moreover, the herd never moved into the eastern part of the park. On-the-ground transect surveys of elephant dung throughout the park produced similar results. The herd's significant differential use of park habitat is likely due to differences in human population densities and how people use the park. For instance,
Results from the dung surveys conducted throughout the park show that elephants are more likely to be found in grasslands, deciduous forest, and riverine forest habitats than in other habitat types. They also show that elephant densities are much lower than we expected. The results suggest that only one female herd lives in the park, with additional male elephants roaming on their own. The herd has around 20 members, but it is difficult to estimate how many solitary males are in the area. Probably fewer than 40 elephants live within Alaungdaw Kathapa, although the habitat seems well-suited to support a larger population.
This is a great decline from numbers indicated by staff surveys from the 1980s, which they estimated 120 to 150 elephants lived inside the park. We believe periodic poaching of elephants and live capture have prevented population growth. Park staff believe that under current management conditions, the wild elephant population in AKNP will continue to decline in numbers because of disturbance, poaching, and loss of habitat resulting from degradation and fragmentation.
National Zoo scientists are working with park staff to develop a management plan to protect and increase wild elephants within the park. The elephant population's recovery requires that poaching be eliminated in the area, so enhanced anti-poaching patrolling and law enforcement are top priorities of the plan. Increasing elephant numbers will require small-population management and genetic management as well as habitat conservation.
This summary map shows Silver Moon's locations from December 9, 2002, through August 5, 2004, when the satellite collar's battery died. The data indicate that Silver Moon and her herd have a home range of about 610 square kilometers, or about 235 square miles. For comparison, the area of Washington, D.C., is about 176 square kilometers, or about 68 square miles. We now have more than 1,100 locations for Silver Moon.