The population of western monarch butterflies wintering along the California coast has rebounded for a second year in a row after a precipitous drop in 2020, but the population of orange-and-black insects is still well below what it used to be, researchers say.

At Oakland's Lake Merritt, a popular spot for joggers, walkers and those looking to be in nature, crews on Wednesday began removing dead crabs, bat rays, striped bass and other fish that began piling up on its rocky shores over the weekend.

The number wintering along California's central coast is bouncing back after the population, whose presence is often a good indicator of ecosystem health, reached an all-time low last year.