A new study has warned of “substantial ecological downsizing” for mammals and birds over the next century.
“Ecological downsizing can entail the loss of unique ecological functions and can impact ecosystem structure, function, and bio-geochemical cycles. Hence, downsizing could be a driver, as well as a consequence, of global change with implications for the long-term sustainability of ecological and evolutionary processes,” researchers from University of Southampton said in findings published in the journal Nature Communications.
“Recent human activities might have generated an extinction debt with the capacity to non-randomly restructure mammals and birds on Earth, with potentially severe ecological consequences,” they said.
The researchers have predicted that the average (median) body mass of mammals specifically will collectively reduce by 25 per cent over the next century, compared to the 14 per cent body size reduction observed in species from 130,000 years ago until now.
The researchers came to the conclusion after looking at five characteristics in 15,484 birds and land mammals: body mass, litter (or clutch) size, diet, habitat, and the length of time between generations.
Using the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, they also predicted the species most likely to go extinct within the next 100 years.
So while critically-endangered species were given a mere 1 percent survival rate, endangered animals were in with a two-in-three chance of survival. Vulnerable animal species were given a 90 percent survival rate.
The findings also show better chances of survival for small, highly fertile and adaptable animals, such as rodents and songbirds, than larger ones such as rhinos, tigers and eagles.
“By far the biggest threat to birds and mammals is humankind—with habitats being destroyed due to our impact on the planet, such as deforestation, hunting, intensive farming, urbanization and the effects of global warming,” the study’s lead author Rob Cooke, a postgraduate researcher at the University of Southampton, was quoted as saying.