Hundreds of mammal species are being pushed toward extinction

A new study led by The University of Manchester has identified that mammal species are being pushed to their ecological limits in areas where they are unlikely to thrive.

The researchers examined whether habitat loss caused by human activity leads to species being pushed into poor-quality environments.

The research, led by Dr. Jake A. Britnell and Professor Susanne Shultz is published in the Proceedings of the National Academy of Sciences (PNAS). Their results suggest that being restricted to poor, marginal habitat is a global conservation threat that is vital to incorporate into conservation assessment and management.

The researchers demonstrate that many of the 627 mammal species with documented range contraction now only occur at the ecological extremes of their historic ranges. 66% and 75% of these species were pushed toward temperature or precipitation extremes, respectively, with the shifts getting worse as species lose more land.

"Human pressures are causing species to lose range. As they lose range, their niches shrink, and they become restricted to a less diverse range of habitats. Our study suggests range loss is concentrated in niche cores, pushing many species to the ecological extremes of their historic range," says Dr. Britnell.

This shift, called ecological marginalization, leads to a higher species extinction risk. According to the researchers, the quality of the habitat matters to a species' extinction risk and ecological marginalization could help to explain why some protected areas are more effective than others.

This shift occurs because areas that are good for agriculture, rangelands and human settlements have been converted for human use. This leads to natural habitats being restricted to areas which humans do not want or cannot use. This study shows that these "remnants" may also be poor quality habitats for biodiversity protection.

"If we are conserving species in fundamentally unsuitable habitats, then conservation may underperform or even fail. Using historical information may highlight more effective places or strategies to concentrate our efforts," says Professor Shultz.

"If species are protected in marginal areas, conservation efforts are already on the back foot as species will not survive or reproduce as well as they can. If we identify and protect high-quality environments, we will bolster more abundant, denser and more resilient populations," says Dr. Britnell.