Over the years, scientists have studied how monarchs arrive and form their overwintering colonies in Mexico. In general, monarchs go through four phases while overwintering there: arrival, establishment of an overwintering colony, colony movement and finally dispersal in the spring. For more information on this process, visit our Population Status page and scroll down to the expandable section titled "Monarch overwintering colony dynamics" to read more detail.
To see a playlist of videos from late November of 2023, visit the Journey North YouTube channel. You can also get weekly updates from the overwintering colonies from Estela Romero via Journey North's Monarch News.
Videos, photos and updates are also posted on the MBF Facebook page.
Updates on the western population of monarchs are found in the Xerces western population count page.