Morphometrics and behavior of a wild Asian elephant exhibiting disproportionate dwarfism

Abstract

Background: Dwarfism is a condition characterized by shorter stature, at times accompanied by differential skeletal growth proportions relative to the species-typical physical conformation. Causes vary and are well-documented in humans as well as certain mammalian species in captive or laboratory conditions, but rarely observed in the wild. Case presentation: We report on a single case of apparent dwarfism in a free-ranging adult male Asian elephant in Sri Lanka, comparing physical dimensions to those of other males in the population as well as in previous literature. The subject M459 was found to have a shoulder height of approximately 195 cm, is shorter than the average height of typical mature males, with a body length of 218 cm. This ratio of body length to height deviates from what is typically observed, which is approximately 1:1, but was similar to the attributes of a dwarf elephant in captivity documented in 1955. We report on behavior including the surprising observation that M459 appears to have a competitive advantage in intrasexual contests. We discuss how this phenotype compares to cases of dwarfism in other non-human animals. Conclusion: M459 exemplifies a rare occurrence of disproportionate dwarfism in a free-ranging wild mammal that has survived to reproductive maturity and appears otherwise healthy.