As urbanisation spreads, battles are raging on holy lands: invasive ants are taking over the leaf litter in sacred groves.
Sacred groves, known as devaru kadu in Kannada and kavu in Malayalam, are fragments of forests protected by local communities. Hunting and logging are not permitted here. The result is that many sacred groves still stand tall in urban areas as well. While these islands of forest are crucial refugia for local wildlife, are they still untouched by the effects of urbanisation around them?
To find out, a team of scientists from the Central University of Kerala studied ant species richness and abundance in five sacred groves in both urbanised towns and rural villages in the Kannur and Kasargod districts of north Kerala. They set up pitfall traps – small containers embedded in the ground that ground-dwelling ants fall into – at specific locations, and listed the species and numbers of ants that fell in.
The sacred groves were home to 32 ant species in total. Ant assemblages varied between urban and rural groves; while only five ant species were exclusive to urban groves, nine were exclusive to rural ones. Urban groves were home to larger numbers of ants, and habitat generalists as well as invasives (like the Yellow Crazy ant Anoplolepis gracilipes ) dominated leaf litter here, a clear indicator of human disturbance in the habitat.
“Urban sacred groves supported greater numbers of the Yellow crazy ant,” Sinu P. A., who conducted the study says in an email to The Hindu.
“These do not bite us but damage our crops, are a pest of household items and prey on insects, bird hatchlings, crabs and other native species. In short, they replace native biodiversity.”
Why could urban groves be showing such a significantly different pattern? New residents who migrate from elsewhere and live near sacred groves often dispose waste in the groves, says Sinu. “This might have been a reason for the increased abundance of generalist and invasive ants in urban sacred groves,” he says. Educating the local community about the value of forests could be crucial for conservation of sacred groves and their native biodiversity including minuscule ants, he adds.
