It will soon be legal to hunt and kill mute swans anywhere in California, after Governor Gavin Newsom signed state legislation into law earlier this month. … Mute swans are territorial and extremely aggressive, and do not mix well with other waterfowl species native to the area. They do not generally migrate and prefer to feed on primarily submerged aquatic vegetation in wetlands, which are limited across California, and are essential for many wetland-dependent birds, native to the state. … Mute swans were first found in the Suisun and Napa marshes during the California Department of Fish and Wildlife’s annual Waterfowl Breeding Population Survey in 2007. 

Related article:

• KIBS/KBOV (Bishop, Calif.): Mute swans added to list of nongame birds that may be taken in California