São Paulo, BrazilThe rampant spread of COVID-19 across Brazil is threatening more than half a century of conservation efforts to protect a small, bright orange monkey called the golden lion tamarin.

Named for their leonine manes and found only in Brazil, golden lion tamarins had shrunk in number to a mere 200 in the 1970s, because of their capture for the pet trade and the destruction and fragmentation of their Atlantic Forest habitat. A series of efforts—ranging from genetic and reproductive research to captive breeding and relocations to habitat areas needing the biggest population boost—brought their numbers back up to about 3,700 by 2014. (Read about the creation a wildlife corridor in the Atlantic Forest to help golden lion tamarins cross a