Date: 01/01/2018

Number: 12360

The second largest California overwintering site in 2017

This wintering site is known as Alder Rd vortex (Larch, Ocean St) in Marin County. It was one of 5 sites that had more than 10,000 monarchs during the annual Thanksgiving Count in November, 2017.

This site's Thanksgiving Count data:
November, 2010: 0
November, 2011: 7,700
November, 2012: 150
November, 2013: 1,013
November, 2014: 3
November, 2015: 4,050
November, 2016: 13,375
November, 2017: 12,360

Summary of 2017 Thanksgiving Count data:
Total reported: 192,629 monarchs
Total counts: 262 sites
Average: 735.2 monarchs


Western Monarch Thanksgiving Count Data from 1997–2017. Monroe, M., E. Pelton, S. McKnight, C. Fallon, D. Frey, and S. Stevens. 2017.

Alder Rd vortex, CA

Latitude: 37.9 Longitude: -122.7

Observed by:
Contact Observer

The observer's e-mail address will not be disclosed.
Contact will be made through a web-based form.