To Catch a Mouse: Chasing Mammals on Recovering Mount Diablo
by Joan Hamilton on July 01, 2014
This article is part of a monthly series of photos and articles on the transformation of Mount Diablo following the 2013 Morgan Fire, funded by special donations from Bay Nature readers. You can find our stories, as well as event listings, iNaturalist sightings, and magazine features, at baynature.org/diablo.
ne April afternoon, some friends are relaxing in an oak-shrouded campground in Mount Diablo State Park. While most munch on guacamole and chips, one squishes together peanut butter and dry oatmeal in a plastic bag. That’s the first clue that these are no ordinary campers—they are mostly scientists following the aftermath of Mount Diablo’s 2013 Morgan Fire. The gooey PB&O is bait for small mammals, which they hope to lure into shoebox-size aluminum traps.
Backpacks bulging, the team strides off for a 3-hour hike, just as they did the night before. They’ll place 40 baited traps in burned grassland, chaparral, woodland, and streamside areas. Early tomorrow morning, before the sun gets too hot, they’ll rescue any captives. With thickly gloved hands, they’ll note the creatures’ species, weights, ages, and sexes—and send them on their way.
This effort, part of the Morgan Fire Research Project, was born inside URS, a Fortune-500 engineering and construction firm. One day over lunch in the company’s Oakland office, three young biologists were chatting about last September’s epic fire. “Wouldn’t it be fun to work together outside of work,” botanist Anna Larsen recalls thinking, “to see the restart of the cycle?’
Larsen and biologists Mandi McElroy and Tammy Lim are well versed in local plants, mammals, reptiles, and amphibians. After recruiting friends from smaller consulting firms and a group called Nerds for Nature, they added brainpower in birds and insects. What they didn’t have was funding. So they decided to monitor Mount Diablo’s recovery as volunteers, on days off, which would make getting things done more difficult. But it didn’t douse their enthusiasm.
“It’s a rare opportunity to be able to monitor regeneration after a fire,” says McElroy. “It fulfills a passion for inquiry.”
With Mount Diablo State Park’s blessing, team members have set up four 20-by-20 meter plots and vowed to survey them regularly. They won a grant from Save Mount Diablo to purchase remote cameras to monitor large-mammal activity. They’ve also set up cell-phone camera stations on the mountain to enable visitors to contribute to the visual record of the mountain’s recovery.
Among the team’s questions: How will the fire affect the 11 plant species that grow on Mount Diablo and almost nowhere else? How will it change the list of animals that live here? Will sensitive species with limited ranges (such as Alameda whipsnakes, Bay Area blonde tarantulas, and dusky footed woodrats) be hurt by the fire? Will resilient species bounce back quickly, or take their time? Will some species wink out completely?
On this weekend in April, though, the questions are simpler. Where should we put the traps? Which habitats are likely to have the most activity? Hopes are high in the once-blackened grassland plot. The grass is already calf-high, a good place for small mammals to hide. The chaparral is greening up too, but there’s a lot of bare ground between skeletal shrubs—not as safe for a rodent scurrying from predators. At the streamside plot, mugwort and monkey flower are thriving alongside glistening mounds of poison oak. McElroy wonders whether they should send the team up that drainage. “They’re biologists,” says researcher Sue Townsend. “They can handle it.”
At 7 a.m. on Sunday morning, the team heads out to check the traps. Following along with them is like watching a well-pitched baseball game. Not much is happening, but excitement could break out at any moment. “It would be really cool to catch something like a Berkeley kangaroo rat,” researcher Greg Pfau says, though he knows the species hasn’t been seen on the mountain since the 1950s. Western harvest mice and deer mice are more realistic possibilities.
On the way to the chaparral plot, researchers sneak by a lethargic rattlesnake. The traps, however, are all empty. In the woodland plot, one of the traps has sprung shut. But, alas, no captive. In the streamside and grassland plots, same story: no kangaroo rats, no mice, no nothing.
“Sorry!” McElroy says. The team’s hidden cameras have recorded larger mammals using these plots, including black-tailed deer, wild pigs, coyotes, gray foxes, raccoons, and skunks. Before drawing conclusions about small mammals, they’ll spend a lot more time in the field, setting out traps in different seasons and for four instead of two nights in a row, to allow fauna to get used to having the boxes around. They also plan to trap in unburned areas, and to compare the results there to those in burned plots.
“That’s what science is like,” sighs Larsen, as she and other researchers head home. It was an inconclusive couple of days, but they’ll be back. They have questions to answer.