By: Eric Wang

As climate change forces tree species to move further north, mice are working around our feet, carrying the acorns that allow for tree migration.

Seed-dispersing animals play a massive part in forests. They determine which species thrive and grow, and which ones dry out, by carrying seeds to new places. Ivy Yen, a biologist at the University of Maine, says, “All the oaks that are trying to move up north are trying to track the habitable range. The only way they’re going to move with the shifting temperatures is with the animals.”

Ms. Yen is a doctorate student of Alessio Mortelliti, a wildlife ecologist, who designed an experiment to determine whether mouse personality and acorn species affect how mice move acorns

For the past seven years, in Penobscot Experimental Forest, located near the towns of Bradly and Eddington in east-central Maine, Dr. Mortelliti’s students have been capturing mice, testing their personalities from bold to shy, and then tagging them with a microchip before releasing them.

In a tray of color-coded acorns that show what species they are, a motion-sensing microchip captures the interaction, while a nontoxic fluorescent powder sticks to the mice’s feet.

In an autumn experiment, most of the activity came from one mouse known as 982091062973077, a 13-gram shy but cautiously adventurous male mouse.

Dr. Mortelliti says, “People see that a forest is regenerating. But what people don’t see is that the forest is regenerating following the decisions of small mammals,” Dr. Mortelliti said.