The Mouse That Survived a Volcanic Apocalypse


The Pinatubo, a quiet volcano on Luzon, the most populous island in the Philippines, was for centuries an ecological Arcadia, a Viridian mountain with an abundance of fauna. One such animal was Apomys sacobianus, the Pinatubo volcanic mouse who spent their days looking for earthworms and other foods.

On June 15, 1991, the apocalypse occurred in Paradise. Molten rock exploded from the volcano, suffocating most of its flanks in overheated, thunderous avalanches of toxic gases and debris that instantly wiped out all life in its wake. Nearly 1,000 feet were sheared from its summit, leaving a 1.5 mile hole and wiping out the surrounding forest.

Ecologists speculated that the Pinatubo volcanic mouse, believed to be up there and nowhere else, went the way of the dodo. To everyone’s surprise, wildlife surveys revealed that this rodent not only survived the outbreak, but thrived too. As reported in the Philippine Journal of Science last month, it became the most abundant mammal on the mountain.

Studying how this mouse made its comeback will help ecologists understand how other mammals can react when greeted by anthropogenic or natural devastation, said Eric Rickart, curator of vertebrates at the Natural History Museum of Utah and co-author of the new study.

This mouse’s dramatic saga also reaffirms an unassailable ecological edict: You should never underestimate rodents, said Christine Wilkinson, a graduate student who studies conservation biology and human-animal conflict at the University of California at Berkeley and who was not part of the study .

“Anyone who’s seen a New York rat knows it has,” she said.

Whether or not you think Apomys sacobianus is cute may depend on your preference for rodents. “It’s a big mouse. Some people would call it a little rat, ”said Dr. Rickart. “It really is a very beautiful little animal.”

Apart from its delightful appearance, little else was known about it. For half a century only a single specimen existed in a scientific warehouse, collected in 1956 on the lower slopes of the volcano. Subsequent field research indicated that the volcano was its only home. Conventional conservation biology suggests that this precariously small habitat was just a catastrophe away from wiping the mouse off the face of the world.

While scientists suggested that this event eliminated it at the extinction level, some were curious to see if there was more to the story. Danilo Balete, a researcher with the Field Museum of Chicago, went to Pinatubo in 2011 and 2012 to see if that fate occurred. Working with field assistants, including members of the Aeta indigenous people, Mr. Balete set traps loaded with worms and roasted coconut treats to capture and capture the local mammal world.

Mr. Balete, also one of the co-authors of the study, died suddenly in 2017 at the age of 56. He was both a leading exponent of Filipino biodiversity science and a dear friend of his colleagues. They felt compelled to complete the work he had begun – and in doing so they found the opposite of what everyone had predicted.

After acute environmental destruction, invading rats from lower elevations should have conquered the mountain and pushed native species aside. “We just don’t see that in the Philippines,” said Lawrence Heaney, curator of mammals at the Field Museum.

The native mammals had refused to surrender much of the soil to opportunistic pests and instead continued to rule their volcanic roosts. It is believed that they clung to small patches of surviving forests and eventually repopulated the slopes of the mountain.

Similar devastating eruptions have occurred in Pinatubo in the distant past. The mouse could have survived through each one and thrive again and again in the post-apocalyptic landscapes. Dr. Rickart said, “We consider it a fault specialist” reveling in devastated environments.

It might seem counterintuitive, but a quiet environment isn’t always the optimal state for life, said Ms. Wilkinson. As various plants, mushrooms, and animals caught in forest fires show, some must be destroyed in order to thrive. And when a ruling ecosystem is dealt a fatal blow, like the asteroid coup de Grâce that visited dinosaurs 66 million years ago, small mammals like to fill the void.

The outbreak was undoubtedly terrible for many. But, as the history of this superhero mouse has shown, “awful” can be a relative thing, “said Dr. Heaney.