Recent checkups on Pacific pocket mice reintroduced to their natural habitat show that the species is once again prospering.
San Diego Zoo Global staff released 50 Pacific pocket mice, a species on the brink of extinction, into Laguna Coast Wilderness Park about a month ago.
Zoo staff laid 237 traps over four days in order to catch the mice and conduct health and wellness checks.
Researchers were able to capture 24 of the 50 micro-chipped mice and found that male mice were reproductively ready while several of the female mice showed signs of approaching breeding cycles.
Before the mice were reintroduced to their habitat, man-made nesting chambers made of biodegradable material were put in place to provide the mice with initial shelter. Researchers used remote cameras to observe the mice.
Staff from the San Diego Zoo Institute of Conservation Research visits the release site three times per week to deliver a supplemental food source to the mice.
“It’s exciting that we were able to observe 48 percent of the Pacific pocket mouse population in Laguna Coast Wilderness Park during our first round of trappings,” San Diego Zoo Institute for Conservation Research's Debra Shier said. “Overall, we’re really pleased with what we’re seeing.”
Pacific pocket mice weigh between six and seven grams, or about as much as three pennies, making them the smallest mouse species in North America.
The nocturnal seed eaters are critical to their ecosystem because they help disperse native plant seeds throughout the habitat. Their burrows also help aerate and hydrate the soil, which leads to increased nutrient cycling and growth of native vegetation.
The species was believed to be extinct in the 1980s until it was rediscovered in 1993. The Zoo’s relocation project is the first of its kind since a captive breeding program began in 2012.