California’s once exponentially growing population of invasive mute swans has fallen by half, less than a year after a new law took effect allowing hunters and landowners to kill them. Over the objections of animal welfare groups, Gov. Gavin Newsom last year signed legislation allowing property owners and those with hunting licenses to shoot the nonnative, destructive swans. The mute swan population had ballooned to about 15,000, most around the Suisun Marsh on the outskirts of the Bay Area. … Wetland ecologists and waterfowl biologists say they represent a profound threat to the struggling wetlands of the Sacramento-San Joaquin Delta. … As their numbers grow, they can quickly eat through a marsh’s submerged native vegetation on which other species rely. 

Other invasive species news:

• KGET (Bakersfield, Calif.): Kern County groups to host golden mussel information forum Aug. 5​