Madagascar: Invasive Rats Are Stopping Small Mammals From Returning to Madagascar's Regenerating Forests - Study

What the report says

A study republished by AllAfrica says invasive black rats are slowing the return of native small mammals to forests regenerating in south-eastern Madagascar. The report, based on work by biologists from Canadian, American and British universities with students from the University of Antananarivo, focuses on forest areas around Ranomafana National Park, where land once cleared for farming has been left to recover naturally. The researchers looked at how wildlife is re-establishing itself as tree cover returns, with attention to birds, mammals and plants.

According to the article, native small mammals such as mouse lemurs, tufted-tail rats and shrew tenrecs were uncommon in the recovering forest plots. By contrast, black rats were widespread, even in areas that had been regenerating for more than five decades. The authors report that sites with more black rats tended to have fewer native species, while protected old-growth forest inside the park showed the opposite pattern. For brown mouse lemurs, the only native small mammal found often enough for detailed analysis, higher rat numbers were linked to lower body weight.

The study argues that restoring vegetation alone may not be enough for full ecosystem recovery if invasive rats remain abundant. It suggests that mouse lemurs may coexist with rats only when rat numbers stay low, and it proposes trapping as a safer control method than poisons, which can harm other wildlife. The findings matter because Madagascar’s forests support unique and endangered species, and the results point to the need to protect intact forest while managing invasive animals in recovering areas.