What caused ducks and geese to die in California?

Avian influenza, commonly known as bird flu, is the cause of the mass deaths of ducks and geese in California. The highly pathogenic strain of the virus, H5N1, has been spreading across the state, affecting both domestic and wild bird populations. The virus is highly contagious and can be transmitted through direct contact with infected birds or their bodily fluids, as well as through contaminated food or water. The rapid spread of the virus has led to significant mortality rates among waterfowl species, with large numbers of ducks and geese succumbing to the infection.