A close-up of a male monarch butterfly. Courtesy Scripps Research Institute

San Diego Zoo Global sounded the alarm Monday after a count in November showed the population of monarch butterflies falling to an all-time low in California.

Preliminary results from the 2020 Western Monarch November Count showed less than 2,000 migratory monarchs in California, which is their primary winter refuge. This represents a population drop of more than 99 percent.

“While we were not expecting to see a rebound in the population this year, we are saddened to witness another massive drop in numbers,” said Emma Pelton, senior conservation biologist and western monarch lead at the nonprofit Xerces Society for Invertebrate Conservation.

Monarch butterflies overwinter primarily on the California coast and migrate to Oregon, Washington, Nevada and other western states in the spring and summer. The species numbered over 4 million as recently as the 1980s.

“The incredible migration of western Monarchs is a unique yet fragile piece of North America’s natural history, and it is on the brink of collapse,” said Paige Howorth, director of invertebrate care and conservation at San Diego Zoo Global.  “We must take targeted, immediate action on behalf of Western Monarchs, and behave as though the future of the western migration depends on it—because it does.”

Monarch populations in California are threatened by a number of factors but conservationists want people to know that there are steps the community can take to save the butterflies:

  • Plant native: Native plants, and in particular native milkweed, give monarchs their best chance for success.
  • Choose nectar-rich plants : Migrating adult monarchs must have access to nectar in the early spring, and they will navigate through urban gardens to get it.
  • Plant now: Get native plants and seeds into the ground ahead of the winter rains.
  • Record observations: Biologists still lack key information about the movement of western monarchs, Add your observations to the Western Monarch Milkweed Mapper or the Monarch Larva Monitoring Project.

Although the San Diego Zoo and Safari Park are currently closed to guests, San Diego Zoo Global’s conservation work with endangered species is continuing.

“We are very focused on the immediate needs and concerns of our community and employees, however the wildlife of the world still need us and we remain steadfast in our global conservation efforts,” said Paul Baribault, president and CEO of San Diego Zoo Global.  “This new information about the monarch butterfly population in California is staggering, and we want to lend our support to the cause immediately.”

Chris Jennewein

Chris Jennewein is Editor & Publisher of Times of San Diego.