As we arrive at Kammerer Ranch — a property owned by the Nature Conservancy, near Alum Rock Park in San José — a very large brown bird swoops up from the hillside. Too big to be a falcon or hawk; not flying like a turkey vulture. A golden eagle, I suggest to Ethan Inlander, a stewardship manager for the Nature Conservancy. Maybe, he says, but he thought he saw some white near the tail. A juvenile? We turn to Kirk Klausmeyer, the third member of our party and a conservation manager at the Nature Conservancy. He didn’t get a good look.

Golden eagle or not, it’s a perfectly clear day, about 70 degrees, with a slight breeze. The three of us remark on how lucky we are to be out on such a day, though clear, sunny days are the norm out here. Anyway, it's ideal for our short hike with the Google Trekker. Introduced in 2012, the backpack has been used at various places including the Taj Mahal and the Galapagos Islands. The Trekker is derived from Google's Street View trucks and is meant to help keep Google Maps at an advantage relative to its competitors, by making sure Google has more images of more areas.

The Nature Conservancy is using the Trekker at the ranch for a different purpose — to monitor climate change. It's one of several groups that are participating in the Trekker loan program, where people can apply to take the Trekker to "hard-to-reach places."

it's as though i'd put my tent at the top of my pack and hung a heavy stove from it



The device itself is unwieldy and comes in two parts: the backpack, which contains GPS, an accelerometer, two monster-looking batteries, and a computer with 256 GB of data; and the cameras — 15 cameras, with a combined 75 megapixels, mounted in a green circle above the wearer’s head. The Trekker is about 40 pounds, but the weight is badly distributed: when I try it on, the camera bobbles as I walk. It’s as though I’d put my tent at the top of my pack and hung a heavy stove from it; my center of gravity is higher, and the bouncy sensation from the cameras throws my gait out of whack. That awkwardness is fine for the dirt roads we’ll be on; I'd hesitate to take the Trekker on a trickier route.

Inlander helps Klausmeyer strap into the Trekker. They will be taking shots of Kammerer Ranch’s blue oaks, a species of California tree particularly threatened by climate change. Though blue oaks are hardy — they can offset the stress of a drought by tapping groundwater resources once they’re past seedlings — even they have limits. Computer modeling has suggested that there will be climate stress here, Klausmeyer says. That’s why the Nature Conservancy is using the Trekker now — to get a baseline picture of how the oaks are doing.

In fact, things are already changing. In four sites studied by naturalists — one of which was the Kammerer Ranch — there were three times more dead oaks in the drier, hotter areas than at the cooler temperatures found at higher elevations. And seedlings found in the study, published in Ecopshere in July 2014, were located closer to streams than adults, suggesting the new trees were growing in increasingly restricted environments.

The Trekker’s 360-degree view should help scientists track how the blue oak populations change over the coming years, Klausmeyer explains. Because the trees are, well, trees, and thus stationary, they can’t simply leave the area as it becomes hotter and drier — and invasive species may out-compete them.

only two-thirds of california's oak woodlands remain

That’s a problem because blue oaks protect soil from erosion and landslides. Oak woodlands provide homes for 330 species — birds, mammals, reptiles, and amphibians — in California. Acorns, for instance, are abundant food for many animals. Only two-thirds of California’s oak woodlands remain, most of them under private management.

Google will host the images and maintain an archive. The Nature Conservancy plans to use the Trekker for photos of Kammerer Ranch every five years for the indefinite future. And the project probably won’t just benefit blue oak conservation — since everything along the route will be shot by the cameras, other species may benefit from the monitoring as well.

We set out. Inlander and I walk well behind Klausmeyer for a brief trip around a pond, where we startle a garter snake and some squirrels. It’s something of a trial run; the longer collection hike is on a loop of ranch roads across the crest of hilltops. For the longer hike, Klausmeyer is solo; Inlander and I walk the opposite direction on the loop so we won’t be in all the photos. Shortly after we set off, Inlander points at a dead oak. It died recently, he says — you can tell because it hasn’t been turned over yet.