Elephants are “ecosystem engineers” that impact other species of plants and animals by changing the environment around them. In Myanmar, Asian elephants walking through mud create deep tracks, which fill with water and serve as egg-laying sites for frogs during the dry season, a time when other breeding habitats are unavailable.
By Thomas Rainwater
Elephants are “ecosystem engineers” that impact other species of plants and animals by changing the environment. For example, browsing elephants remove trees causing grasslands to expand, dung left in wetlands has an important fertilizing effect, and seeds passed through the digestive tract are more likely to germinate.
Creating homes for small animals
Elephants also deliver benefits to smaller fauna; browsing damages trees and creates cavities used by geckos as hiding places, and dung piles provide a home (and food) for many small animals.
In their research article recently published in Mammalia, scientists from the US and Myanmar conducted a biodiversity survey between 2016 and 2017 at a wildlife sanctuary in northern Myanmar. At the sanctuary, elephants trundling through the mud around seasonal wetlands leave deep tracks, some of which fill with water. Owing to their immense bulk, trampling by elephants probably changes the soil structure, making the tracks better able to retain water during the lengthy dry season (October through May) when most wetlands contain no water.
Elephants’ trampling creates mini pools for frogs
Taking advantage of these miniature pools, frogs lay their eggs in them and tadpoles develop in the tracks. Water-filled elephant tracks offer several advantages to breeding frogs. First, these tracks provide critical nesting sites that are available at a time of the year when most other small pools are dry.
Waterholes in the dry season
Second, tracks are free of predators such as small fish, that might consume eggs and tadpoles. Third, groundwater seepage appears to keep tracks filled with water through the dry season, providing ample time for tadpoles to complete metamorphosis into frogs.
And fourth, water-filled tracks could function as “stepping stones” connecting different breeding populations of frogs across the landscape, an important consideration where gene flow is concerned. These observations provide yet another example of how environmental changes wrought by elephants can positively impact other species.
Their vital role in the ecosystems
The role of Asian elephants as ecosystem engineers is poorly understood, with most research on this topic being focused instead on the two species of African elephants.
Observations of frogs using water-filled tracks as breeding sites in Myanmar provides one of the few examples of engineering by Asian elephants, and complements another study from India that found dung piles served as important habitat for frogs and invertebrates.
“Urgent need for better understanding”
Study author Thomas Rainwater says, “Together, these studies highlight the urgent need for a better understanding of the ecosystem engineering role played by Asian elephants, especially in light of their rapid global decline.”
Read the original article here.