Butterflies overwinter here, mainly on eucalyptus trees (shown) and also Monterey pine, from late November through February. Over the past decade or so, population has ranged from 20,000 to 350,000. This year, there were about 25,000 in attendance, though we saw far fewer than this number.

A naturalist at the site reported that the butterflies didn't move much with ambient temperature below 50, as it was on the day these photos were taken. He said they wanted to get their body temperature to about 100. These Monarchs perched with wings spread and almost appeared to be in formation when in small groups. This approach contrasts with the more often seen photos with wings together, which is an attempt to conserve heat on cooler days.