Monarch Butterfly Migration



Every year, millions of monarch butterflies (Danaus plexippus plexippus) perform annual migrations across North America from southern Canada to overwintering sites in central Mexico. This 3,000 mile migration is one of the most spectacular natural phenomena in the world. The butterflies begin their journey in September/October and arrive in Mexico around November, with their peak populations in the 200 square mile Monarch Butterfly Biosphere Reserve in February. They start the return trip in March, arriving back where they began their journey around July. They travel about 12 mph and cover about 80 miles a day; therefore, no individual butterfly completes the entire round trip; female monarchs lay eggs for the next generation during the northward migration and at least four generations are involved in the annual cycle.

Unfortunately, the winter sanctuaries in both Mexico and California were declared to be threatened phenomena by the International Union for the Conservation of Nature and Natural Resources (IUCN) in the IUCN Invertebrate Red Data Book. A number of traits make monarchs vulnerable to a changing climate. Like most butterflies, monarchs are highly sensitive to weather and climate: They depend on environmental cues (temperature in particular) to trigger reproduction, migration, and hibernation. Their dependence on milkweed alone as a host plant is a further vulnerability, particularly as milkweed abundance is declining throughout the monarch range. They also face a decline in their overwinter habitat, and the effects of an increasing frequency of extreme weather events such as drought and severe storms, and extremes in hot and cold temperatures.


“We have a lot of habitat in this country but we are losing it at a rapid pace. Development is consuming 6,000 acres a day, a loss of 2.2 million acres per year. Further, the overuse of herbicides along roadsides and elsewhere is turning diverse areas that support monarchs, pollinators, and other wildlife into grass-filled landscapes that support few species. The adoption of genetically modified soybeans and corn have further reduced monarch habitat. If these trends continue, monarchs are certain to decline, threatening the very existence of their magnificent migration.” O.R. Taylor 

There are a few different locations within two states to visit the monarchs in their Mexico location:



  • – Piedra Herrada
  • – Cerro Pelon sanctuaries


  • – El Rosario Santuario de la Mariposa Monarca
  • – Sierry Chincua Santuario de la Maripos Monarca

You can visit these locations as a day trip to Mexico City or Morelia, or you can stay in the village of Angangueo. Alternatively, making a weekend of the adventure and staying in the wonderful city of Valle de Bravo is my preferred method of experiencing the butterflies. The butterfly reserves are open daily from mid-November through March from 9am-6pm, but February is the best time to visit as the monarch concentrations are highest at this time.

The butterflies weigh down the trees prior to the sun reaching them and this is worth seeing for yourself. However, they won’t take flight until the sun hits them and millions of butterflies flying around you is also a magical experience that should not be missed. In February, the sun begins to hit the butterflies around 11am or so, so try to plan your trip to arrive to the top around 10:00-10:30 am, if possible, and be sure to stay long enough to see the butterflies take flight.


Do not expect the journey to the top to be easy; each reserve has a steep journey to get to the congregation of butterflies. You can hike the trails, but they are very dusty and it can make it difficult to breathe. Alternatively, you can rent a horse to take you up and down. This keeps you a bit above the dust and lessons the difficulty a bit. Be sure to wear a mask to help reduce dust inhalation. Bring plenty of water, wear comfortable shoes, and dress in layers as the temperature can get quite chilly with the elevation. Most importantly, bring your sense of adventure and your cameras!

The factual information above was collected from Wikipedia and the World Wildlife Fund. For more information about the phenomenal monarch migration, please refer to the following sites:…/monarch-butterflies-and-cli…


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