Avian botulism has raised alarm at Tulare Lake, prompting an immediate Coordinated Response. Revived by a wet winter and spring, Tulare Lake has become a hub for various bird species. Once a sprawling freshwater reservoir, the lake’s revival attracted various water birds as it reappeared from the pastures and farmlands of southern San Joaquin Valley, and with the coming fall migrations, millions of waterfowl, shorebirds, and other avian species are expected to make their way to the reinvigorated lake. Growing concerns over stagnant and warming water conditions have led the CDFW to initiate a comprehensive strategy involving aerial, ground, and water surveys.
Avian botulism, a potentially fatal illness caused by toxin type C, has been identified in two specimens collected from Tulare Lake—a mallard duck and a white-faced ibis. Laboratory tests confirmed the presence of this toxin type, which has historically been linked to avian botulism cases involving waterfowl and shorebirds. Additionally, low pathogenic avian influenza viruses were discovered in these birds, though not the highly pathogenic form (HPAI). Another mallard duck tested positive for low pathogenic avian influenza, out of the total 13 birds tested.
A united front has been formed in response to the emerging threat, consisting of agencies such as CDFW, the California Office of Emergency Services, the U.S. Fish and Wildlife Service, the California Natural Resources Agency, the Federal Emergency Management Agency, and the California Waterfowl Association. Collaboratively, they are orchestrating efforts to mitigate the situation.
Aerial surveys are currently underway to gauge the scale of the issue and gather data on bird populations at Tulare Lake. Complementary efforts involve the use of airboats to locate and recover deceased and severely ailing birds. CDFW Senior Environmental Scientist Evan King emphasized the importance of prompt action, stating, “Removing carcasses will be the first step of defense in preventing further spread…”
Residents must report wildlife mortality to CDFW for vital insights, supporting ongoing biologist monitoring around Tulare Lake.
