Taking a Wood Rat census at Pulgas Ridge Open Space Preserve

Last month my son and I were high up on the ridge at Pulgas, and his energy was flagging. We still had more than a mile to go before we were done, so I proposed that we count wood rat nests on the way back to the trailhead. We had such fun (and came to a surprisingly large number) that yesterday we went back and did it again. This time we counted the entire 4.1 miles -- stringing together Hassler, Dusky-footed Wood Rat, Dick Bishop, and Blue Oak trails.

Woodrat nest on Dusky-footed Wood Rat Trail (notice the human-trimmed branches)

Once you start seeing wood rat nests it's impossible to stop noticing them. Some of the piles of sticks are low rises while others look like they might be hotels. The rats are nocturnal, so you're not likely to see them on a hike. They prefer nesting in somewhat open shaded woods, but we saw plenty of nests in the chaparral part of the preserve. Our most entertaining find yesterday was a nest on the path on DFWRT -- my guess is that the small tree fell onto the trail, the woodrats immediately nested in it, and then preserve staff came and scratched their heads about the situation. What they did (good decision!) was to trim the branches that were blocking the trail, so that hikers could pass this woodrat campsite.

Like any good experiment, our efforts brought up new questions -- is the population stable, how long do nests last, how many rats in a nest, will we see more nests in spring? We're planning to get a hand clicker for our next hike!

So how many nests do you think we found? I'll post the answer in a few days. If you have a guess please post it.

Go count them yourselves here: http://bahiker.com/southbayhikes/pulgas.html