News – In June 1991, Mount Pinatubo, a volcanic peak on the Philippine island of Luzon, erupted. It was the most powerful volcanic eruption of the 20th century, ten times stronger than Mount Saint Helens, and its impact was devastating. Lava and ash spawn into the surrounding environment in the Zambales Mountains, coming together in layers up to 600 feet thick in the valleys. After the eruption, powerful typhoons and monsoon rains provoked landslides and ash streams that followed for several months. Eight hundred people lost their lives, and the fertile forests that covered the mountain before the eruption were destroyed or severely damaged. In the last few years, scientists have returned to the area to study the surviving mammal populations, and in a new paper in the Philippine Journal of Science, the team announced that -see a long-extinct mouse species.
“When Pinatubo blew up, it was probably the last thing on anyone’s mind that it was thought that there were only a few mice living on that one mountain, and that they may have become extinct as as a result. What we learned afterwards distracted us, ”said Larry Heaney, Negaunee Curator at Mamalan at the Chicago Field Museum and one of the paper’s authors.
In early 2011 and again in 2012, twenty years after the explosion, Field Museum researcher Danilo (Danny) Balete went to Mt. Pinatubo to study the mammal animals. Over several months, Balete and his team of field assistants (including local men from the Aeta tribe) studied the mammals on the mountain, from the bottom to near the top where it was found. the forest was destroyed by the explosion.
“Most of our fieldwork on Luzon and elsewhere in the Philippines has been in natural wooded habitats where mammals are prevalent,” said Eric Rickart, Spinekeeper at Home Utah Natural History Museum and lead author of the paper, “but Danny couldn’t afford to see how mammals fished on Mt. Pinatubo. ”
No mammals have been studied on Mt. Pinatubo before the explosion. However, samples held by the U.S. National Museum of Natural History provided some records from lower elevations around the mountain. “Most of these early records were for common species of bats collected in the 1950s,” said Heaney, “but one sample was particularly interesting – a small rodent that became a true sample, and the only an example of a new species described in 1962 as Apomys sacobianus, Pinatubo volcano mouse. ”
Contracts on Mt. Pinatubo was very tough, and the exploration work by Balete’s team was both grim and dangerous. Even after 20 years, evidence of the explosion was everywhere. The landscape was extremely unstable due to the constantly declining ash and lahar deposits and dangerous working on the steep ground. It also severely delayed the plant succession process. Vegetation was a rare mix of native and non-native plants, thick patches of grass (including bamboo), shrubs, low-growing grapes, and very few trees – all of which are common in early second growth habitat. It was a bit far from the old-growth tropical forest that covered the mountain before the eruption.
Field studies of small non-flying mammals elsewhere on Luzon have revealed a high mix of native species in mature forests and very few non-native rat species “pests”. But in severely disturbed second-habitat habitats, especially in areas close to cropland, the situation is reversed – non-native rats are most abundant, and there are only a few species. hard native. “We thought the work on Pinatubo would confirm this general pattern, so we expected to see very few native species,” Rickart said.
A specific reason for Pinatubo’s investigation was to find out what happened Apomys sacobianus, the Pinatubo volcano mouse. “After the Pinatubo eruption, we looked for this mouse on other peaks in the Zambales Mountains but did not find it,” notes Heaney, “suggesting a very small geographical rotation for the species. We thought maybe the volcano was the only place this mouse lived. ” And based on expectations from islands elsewhere, at the time the species seemed to have been lost due to the eruption.
However, the Pinatubo study yielded truly remarkable results – 17 species were recorded, including eight bats, seven rodents (five native species and two non-native species), and even two large mammals (wild boar and deer ). Contrary to expectations, non-native rats were not common and were restricted to areas near the Aeta crop ground where agricultural pests are usually abundant. Despite the fact that all areas surveyed supported sparse, secondary vegetation rather than forest, native rats were abundant everywhere.
Surprisingly, the most abundant species was, by far, the volcano mouse Apomys sacobianus. Where it was not destroyed by the eruption, this species thrived in this highly confused landscape along with other native species that have a high tolerance for disturbance. “For some time, we have known that many small mammals in the Philippines can suffer from habitat disturbance, both natural and human,” Rickart said, “but most are widespread in space, not local endemic species. which is usually seen by very vulnerable conservation biologists. “
As Mt. Pinatubo will recover from the damage caused by the eruption, the woods will return and other mammal species will move in. ”Mt. Pinatubo could be a great place to set up a long-term project to monitor habitat recovery and community reconstruction after the explosion, ”Rickart said,“ such information would be useful in efforts to regenerate many areas that have been deforested by humans. ”
After completing the Mt. Pinatubo mammal surveyor Danny Balete returned to the Field Museum where he compiled samples and data from the survey, made early notes for final publication, and then set them aside for later completion. forward. After his sudden death in 2017 at the age of 56, Rickart and Heaney say they picked up and completed the study in praise of Balete, who is now recognized as one of the most important figures in Philippine biodiversity science for its extensive research contributions, support of younger colleagues, and encouragement of nature enjoyment throughout the Philippines.
“Knowing that a sex that was once vulnerable, even extinct, is really thriving is the best obedience to Danny we can think of,” Heaney said.