Approximately 40 acres of showy milkweed were planted near Abbott Lake in the Feather River Wildlife Area in Sutter County in February as part of a  habitat improvement project facilitated by River Partners, the California Department of Fish and Wildlife, the Xerces Society and science leads from Washington State University to attract endangered monarch butterflies.

With monarch butterfly populations reaching dangerously low levels last year, a habitat improvement project is underway near Abbott Lake in the Feather River Wildlife Area in Sutter County.

River Partners have begun a statewide project with a coalition of scientists and conservation partners – including the California Department of Fish and Wildlife, the Xerces Society and science leads from Washington State University –  to reintroduce monarch habitats by planting a variety of milkweed variants with the hopes of attracting the endangered butterfly species to several key locations across the state during their migration, including the area near Abbott Lake -- located inside the levee along Garden Highway about halfway between Yuba City and Nicolaus.

Asia Jones, restoration biologist for River Partners, said monarch butterflies have been on a death spiral in recent years, with fewer than 2,000 monarch butterflies recorded overwintering on the California coast in 2020.

According to Jones, this represents a 99.9 percent decline since the 1970s and 1980s, when populations were estimated to be about 4.5 million.

By 2017, Monarch butterfly populations were down to about 30,000, said Jones, which researchers believe was a crucial turning point towards extinction.

Jones said the primary drivers of the decline in populations are a loss of overwintering, breeding and migratory habitats in California, as well as pesticide use.

According to Jones, Monarchs lack state and federal legal protections to keep their habitats from being destroyed or degraded and with much of the Central Valley used for agriculture, most of the milkweed in the area has been removed.

Dr. Hillary Sardiñas, pollinator coordinator for the California Department of Fish and Wildlife, said this project will reintroduce milkweed to crucial areas and provide breeding locations for monarchs in the Central Valley.

“Monarch caterpillars can only use milkweed as their host plant, therefore we planted clusters of showy milkweed,” said Sardiñas. “The western monarch population overwinters along the California coast, migrating to breeding sites throughout the west in the spring and returning each fall. During this migration, many monarchs pass through the Central Valley, therefore it is important to provide breeding or stopover habitat with resources that support these iconic butterflies.”

Utilizing a $1.21 million grant from the Wildlife Conservation Board, River Partners and their partner organizations have plans to plant 595 acres of milkweed and nectar-rich plants along rivers and streams in California from the northern Sacramento Valley to San Diego County.

“It’s one of the largest coordinated monarch habitat restoration projects in the western United States,” said Jones.

Jones said the Abbott Lake location is the third and most recent site to be planted but a fourth location is slated to be planted within the week.

The other locations included in this project are the Oroville Wildlife Area, Upper Butte Basin Wildlife Area near Chico, the Yolo Bypass Wildlife Area near Sacramento, Dos Rios Ranch near Modesto, Panorama Vista Preserve in Bakersfield, the North Grasslands Wildlife Area (Salt Slough) near Los Banos and the Hollenbeck Canyon Wildlife Area near San Diego.

The project

Approximately 40 acres of showy milkweed was planted at the Abbott Lake location in February, said Jones, in two large plots and ten small plots.

Jones said milkweed was planted in different sized plots to study what habitats the butterflies are more attracted to in an effort to further understand their habits. They will also be studying if monarch butterflies prefer habitats that are shaded or unshaded, said Jones.

All research compiled from this project will be shared within the science community to further monarch butterfly preservation efforts, said Jones.

Angela Laws, endangered species conservation biologist for the Xerces Society, said the partners will monitor for monarchs and other pollinators through the summer to measure how much the habitat restoration work benefits the pollinator community.

Once the milkweed have had a chance to sprout and mature, Jones said River Partners will also be performing a census at the site to determine the survival of the milkweed rhizomes and also look for monarch eggs and larvae.

Jones said monarch butterflies typically migrate in late spring and early summer, so they will be keeping their eyes peeled and hoping to spot an increase in populations this year.

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