Just after sunrise on a still-cool July morning, Carla Cicero bushwhacks through a willow thicket in northern California’s Lassen Volcanic National Park. A column of sleepy-looking graduate students follows her, many of them hauling packs draped with netting, aluminum poles, and canvas bags. Chirping loudly but unseen in the branches above them are the songbirds they seek. Although Cicero, a curator and researcher at UC Berkeley’s Museum of Vertebrate Zoology, is going off-trail, she’s following a track rich with history. Eighty years ago, zoologist Joseph Grinnell trekked through this park–and all across California–meticulously describing and collecting the wildlife he found. Cougars and pikas made his list, but also ordinary creatures like finches, mice, lizards, and salamanders. Grinnell eventually surveyed 50 sites in Lassen over a six-year period and collected more than 4,500 specimens.
But Cicero’s work is no historical reenactment. Similar research elsewhere in the Sierra and a steady rise in temperatures are fueling scientists’ concerns that climate change and other factors may be altering wildlife ranges in the heart of Grinnell’s old stomping grounds. To test these theories, Cicero’s field team is part of a multi-year effort to retrace Grinnell’s biological audit of California’s high country. For the last five years, groups from the Grinnell Resurvey Project have covered the state from San Jacinto Peak in the south to the Warner Mountains 550 miles to the north. Instead of relying on computer models or remote sensors, they are climbing peaks, setting traps, and acquiring samples–just like Grinnell did. By collecting from the same areas and comparing new findings to historic notes and drawings, they hope to learn how habitats have changed, which species have vanished, and if global warming is playing a role.
After a two-mile hike, Cicero’s team arrives at a clearing near Manzanita Lake and quickly goes to work. Some swing machetes to enlarge the area, while others stake out poles and nets to create a nearly invisible, featherlight barrier 12 feet high and 36 feet long.
Within a few minutes a brown creeper flies blindly into the fine threads–the first capture of the day. Yellow warblers, fox sparrows, Cassin’s purple finches, and other species soon follow as the team sets up additional nets around the lake. Researchers identify and count the trapped birds, then either release them or collect them for the museum.