are two migratory populations of monarchs in North America.
is much uncertainty about the exact distribution of these populations!
follows is a generalized summary.
Monarchs (in red
The bigger monarch population breeds east of the Rocky Mountains
throughout much of the central and eastern U.S.
They overwinter on 12 mountaintops Mexico. Most
Journey North migration reports highlight sightings of these
Western Monarchs (in yellow
There are 200 to 300 small monarch colonies that winter
within 5 miles of the Pacific Coast from Ensenada, Baja California
(31.5 N latitude) to Marin County, California (38.1 N latitude).
The breeding ground resources are not known, but are assumed
to run from California north to Washington and across the Sierra
Nevada to Nevada and other western states.
More About Western Monarchs