EPOW - Ecology Picture of the Week

Borneo Pygmy Elephant (middle), Asian Elephants (left and right)
The Oregon Zoo, Portland, Oregon

Explanation:   Three elephants in a zoo ... but the middle one is not a baby.  It is a full-grown pygmy elephant.  

Pygmy elephants are rare inhabitants of the island of Borneo.  They are a good one meter (three feet) shorter than their Asian elephant cousins, as seen in this week's photo.  

Pygmy elephants are threatened with extinction in their native habitat.  They are found only in the northeastern part of Borneo, where their preferred habitats of lowland tropical forests are also favored by loggers and for clearing for oil palm plantations.  

Taxonomists include the Borneo Pygmy Elephant with the same species as Asian Elephant but some also differentiate it as a separate subspecies (Elephas maximus borneensis).  

The Borneo Pygmy Elephant may be an example of "insular dwarfism" whereby mainland forms of mammals sometimes evolve into far smaller forms on resource-constrained islands.  Examples of insular dwarfism are common throughout the world, and some scientists even speculate that islands may have once held dwarf dinosaurs.