December 2017 - Monarch butterflies (Danaus plexippus plexippus) have begun their migration to wintering sites in California, including Rob Hill Campground in the Presidio. Monarch numbers have been low at this site over the last 20 years, but the last two years have shown record numbers, with 250 spotted in 2016. Counts happen around Thanksgiving, and again in the New Year, so 2017/2018 counts are still underway.
In addition to these two formal surveys, which are led by the Xerces Society, future monarch counts in the Presidio will also include school groups that come out several times throughout the season. Managers hope that the additional information they provide will help paint a more complete picture of the wintering butterflies’ population size at this site as well as their movements. Learn more about the Presidio’s monarchs in this new video.
Last updated: December 28, 2017