AMBATOMIRAHAVAVY, Madagascar — In a nature reserve on the banks of the clay-colored Katsaoka River, an eight-week-old crowned sifaka clung to its mother’s back as she leapt across tree branches. Nearby, other lemur species combed their young’s backs, nibbled on leaves or lounged in the sun.

Some had white fur, or brown patches, or tails with 28 black-and-white rings. All had one thing in common: endangerment by rampant deforestation and climate change, which threaten the island nation’s future.

Pope Francis used his first full day in Madagascar to hammer the same point home.

“Your lovely island of Madagascar is rich in plant and animal biodiversity, yet this treasure is especially threatened by excessive deforestation, from which some profit,” Francis said Saturday in Madagascar’s capital, Antananarivo, about an hour’s drive from the lemur reserve. “The last forests are menaced by forest fires, poaching, the unrestricted cutting down of valuable woodlands.”

Francis has been making a similar case since his election in 2013, when he put environmental protection and global warming at the top of his agenda. He championed the Paris climate accord and, in 2015, became the first pope to dedicate an encyclical to protecting the earth.