Western monarch count drops in 2023 up and down the coast; P.G. drops by half.

The annual Thanksgiving count of monarch butterflies last fall saw a dip in the number of the insects at 256 overwintering sites on the West Coast, more in line with 2021 numbers, the Xerces Society announced Tuesday, Jan. 30. The total number was 233,394, down from 335,479 in 2022. In 2021 the number was 247,246.

The Pacific Grove Monarch Sanctuary saw a nearly 50-percent drop: 6,508 in 2023, versus 15,960 in 2022. The Pacific Grove Natural History Museum, which is in charge of the trained volunteers who count monarchs in the sanctuary all season, reported over 7,000 butterflies just a week or so before the official Thanksgiving count began on Nov. 11. The count ended Dec. 3. 

The museum reported 3,049 on Friday, Feb. 2. The season, which usually begins around early October, is winding down and will end around the end of February, as monarchs make their way back north.

The largest cluster of monarchs in Monterey County were reportedly on private property in Big Sur, with 8,700 monarchs tallied.

Southern California fared better, with the largest count at just over 33,000 butterflies on land owned by the Nature Conservancy in Santa Barbara County. (The land is not open to the public.) The second and third largest gatherings of monarchs were in the Pismo Beach Monarch Butterfly Grove and the Morro Bay Golf Course respectively. 

There was a record of over 400 volunteers and partners registered to participate in the Western Monarch Count, according to a Xerces press release.

Pacific Grove received a special shoutout: a visitor to the sanctuary spotted a butterfly that had been tagged by the Southwest Monarch Study—the butterfly traveled over 700 miles to reach P.G. Local volunteers in P.G. identified four new overwintering sites, according to Xerces.

The society said that western monarchs remain imperiled, at just 5 percent of their numbers in the 1980s.