Fall and Spring Monarch Butterfly Migration Map

The National Wildlife Federation (NWF) has been advocating for monarch conservation through various programs, projects and community-based projects that promote the expansion of quality habitat and local action, some of which are listed below:

• Mayors’ Monarch Pledge
• Monarch Stewards
• Monarch Heroes
• Garden for Wildlife
• Certified Wildlife Habitat
• Taylor Morrison Monarch Pledge

This map was produced in collaboration with graphic designers, monarch science experts within NWF and external collaborators. Monarch Watch provided the base map which our team used as a reference in order to ensure accurate geographical representations. We layered additional geographical and scientific information onto this base map. We thank and value the input from all our staff and partners that has led us to producing NWF’s first monarch migration map. Context regarding our external sources will be below.

Notes about the Eastern Monarch Migratory Pathway:

It’s important to note that the science regarding North American monarch migration is still developing. Therefore, our map may exclude some hyper-local data regarding monarch migration and breeding areas. Our map does not currently include information regarding monarch breeding activity in Mexico, due to the fact that current observations haven’t provided enough data to map this activity.

Our map doesn’t not currently showcase Mexico’s eastern monarch breeding areas. The generation of monarchs that overwinter in South-Central Mexico migrate north to lay eggs in Northern Mexico and the Southern U.S. Currently there isn’t enough data on monarch sightings in Northern Mexico to make clear geographical distinctions about these breeding areas, so it is not reflected in this iteration of the monarch map.

Notes about the Western Monarch Migratory Pathway:

There is some public data that suggests that some western migratory monarchs can also overwinter in parts of Arizona. As more relevant information and data regarding this overwintering population is available we will assess how to address such findings in this map.

References and Source Materials:

• USDA Plants Database: Range and distribution of showy milkweed (Asclepias speciose) west of the Rocky Mountains.
• BONAP: Range and distribution of showy milkweed (Asclepias speciose) west of the Rocky Mountains. Based on BONAP reports, milkweed is more common on the light green, and less common on the dark green. Thus, we cannot state plainly that there is no presence of monarchs or breeding activity in that area.
• Xerces Society: Xerces Society’s monarch map was a helpful resource in determining the scientific accuracy of the eastern and western monarch migration patterns. In addition to collaboration with Xerces scientists we were able to accurately represent the summer and spring breeding areas for the Western monarch and the unconfirmed coastal migration patterns from Mexico’s overwintering areas to Arizona.
• Southwest Monarch Study---The State of Danaus plexippus in Arizona: Background information on monarch overwintering in Arizona.