Birds Blog

Monarch Migration

Learn about Monarch migration.

Monarch migration was in full swing this weekend in Cape May, N.J.

Monarch in the Breeze. Image Credit: Animal Perspectives.

Magic was in the air, in the form of these orange-winged beauties. Everywhere I looked there they were dancing in the breeze — Red Admirals, American and Painted Ladies too!

Red Admiral. Image Credit: Animal Perspectives.

Monarch Migration

The Cape May Bird Observatory of the New Jersey Audubon has a Monarch Monitoring Project. Monarch monitoring began in 1991 with the intent to resolve a long debate about whether or not the same Monarchs that migrated south through New Jersey were part of the same population that overwintered in Mexico.

Map of Cape May, N.J. Image Credit: WikiCommons License 3.0.

It turns out, that after many years of tagging, seven Monarchs that had been tagged in New Jersey were recovered in Mexico. That’s approximately 2,500 miles!

Tagged Monarch. Image Credit: WikiCommons License 3.0.

The overwintering site for Monarch butterflies was only known to the rest of the world in 1975.


Monarch on milkweed. Image Credit: Animal Perspectives.

The Monarch butterfly has been in trouble for some time. How did America’s most popular butterfly become the victim of such population decline? Three main reasons:

  • Habitat loss
  • Climate change
  • Pesticide use

Habitat Loss

Habitat loss happens because of land development. Urban sprawl, agriculture, tourist attractions, and roadways all need land in order to exist.

Urban sprawl means homes, homes mean manicured lawns. Lawns are not suitable habitats for wildlife. Birds, butterflies, insects, mammals, plants, cannot thrive in that type of “habitat”. Lawns are monocultures and cannot support a diverse array of species.

Climate Change

Climate change has caused unusual fluctuations in weather patterns such as extreme weather. Extreme weather can impact Monarch migration, cause phenological mismatches, all to the detriment of Monarchs and other species of insects, wildlife, and plant life.

Pesticide Use

The Monarch’s host plant is milkweed. There are numerous species of milkweed. Pesticides inhibit the growth of milkweed and kill existing plants. That impacts the eggs and larva that need the plant in order to survive.

How to Help

According to the U.S. Fish and Wildlife Service, Monarch populations have been on the decline for over 20 years. Restoring grassland habitats, which provide opportunities for species richness, is one of the most important steps towards improving populations.

The most important step you can take at home is to plant milkweed and to plant native nectar plants. Also, if you garden, garden organically. Gardening organically reduces the amount of pesticide use.

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