3602 Inland Empire Boulevard
Ontario, CA 91764
FAX: (909) 481-2945
Salton Sea Birds
Lead CDFW biologist: Karen Riesz
Birds go great distances during migration, and many of them pass through the big expanse of desert in California. They need places to stop, rest and eat during their journey. We are losing valuable aquatic habitat to development and climate change, and places like the Salton Sea become invaluable resources for birds.
Birds use the Salton Sea for a variety of reasons. Although the Sea is incredibly salty, the rivers and agricultural drains and canals that empty into it are fresher, and the birds congregate at the places where these features meet the Sea. There is abundant food at the Salton Sea: fish for piscivorous birds like pelicans, and invertebrates for shorebirds. The Sea is huge, so there is plenty of habitat, and a variety of habitat, too. Unlike L.A. or San Francisco, there are very few people who live around the Salton Sea, which creates little to no disturbance. There used to be a large number of people who would recreate on the Sea, but there are very few people who do so now. Furthermore, these birds are fairly safe from predators. Coyotes and raccoons exist, but not in the numbers that could really make a dent in the populations out there; however, there are some nesting species that may be vulnerable.
Over 400 species of birds have been recorded using the Salton Sea and the surrounding area. There are a handful of listed species that can be found there, but the most impressive aspect of the Salton Sea is the sheer numbers of birds.
Salton Sea Bird Health and Disease Monitoring
Several diseases are common around the Salton Sea, mainly because the birds congregate in such large numbers. It's just like being cooped up inside with a bunch of people when the weather is bad during cold and flu season. CDFW responds to bird disease outbreaks by collecting sick and dead birds in an effort to break the disease-spreading cycle.
Avian botulism, caused by bacteria, usually occurs in the spring time when the winds are very strong and push all of the old, deoxygenated water from the bottom of the Salton Sea to the top, depleting the oxygen available for the fish, causing them to die. As the fish die, the birds eat them, and get sick from contracting the bacteria. The birds then die and get feasted on by maggots which then infect birds feasting on the maggots. This can result in massive bird mortality. The species most affected by avian botulism are waterfowl and shorebirds.
Avian cholera, caused by bacteria, tends to happen in winter, when birds like waterfowl come to stop at the Salton Sea during their migration. The birds are tired and therefore more susceptible to getting sick. It's transmitted by bird-to-bird contact, contact with secretions or feces of infected birds, or ingestion of food or water containing the bacteria. Avian cholera kills birds fairly quickly. Sometimes massive bird mortality results, but not always. Salton Sea birds most affected are waterfowl and gulls.
Salmonellosis, caused by the bacteria salmonella, often occurs in nesting colonies where nests are so close together that feces are easily spread from one nest to another. It usually doesn't result in large outbreaks. The birds usually affected are herons and egrets.
Newcastle disease, caused by a virus, often affects cormorants at the Salton Sea. It's spread in bodily fluids and feces. This can be disastrous if it happens during nesting season, but sometimes only a small group of birds die.
Avian Influenza (Type A Influenza)
The low pathogenic form of Avian Influenza naturally circulates in wild bird populations, especially waterbirds. The virus is spread directly in feces or other secretions and in contaminated food/water or equipment, feathers, bedding, etc. Surveys are conducted at the Wister Unit of the Imperial Wildlife Area annually, depending on funding. These surveys involve the testing of particular hunted waterfowl species, usually northern pintail, northern shoveler, green-winged teal, and American wigeon. They are typically conducted once a month during the waterfowl hunting season. This is a volunteer program in which hunters can choose to allow a CDFW biologist to take swab samples from their ducks, which are later sent out to a laboratory for testing. As of yet, Avian Influenza has not been detected within the United States.
Aerial Surveys for Pelicans and Cormorants
Aerial surveys are conducted in the winter and spring in which the white and brown pelicans and the double-crested cormorants are counted. There are stations separated into segments and areas to assist with counting. For example, Mullet Island is one of the stations. Every year, colonies of double-crested cormorants have been nesting on Mullet Island. The highest inland population of breeding double-crested cormorants often occurs at the Salton Sea.
Airboat surveys for disease surveillance
Airboat surveys do not follow any particular protocol. We use airboats for a variety of reasons, but mostly for disease monitoring. CDFW picks up sick and dead birds to try to prevent the spread of disease. The dead birds go to the FWS Sonny Bono Salton Sea Refuge where they either get sent off to a laboratory for testing or get incinerated, and the sick birds usually go to a rehabilitation center. Birds can recover from avian botulism, salmonellosis, and Newcastle disease and be released without spreading the disease. Birds infected with avian cholera die before they have a chance to be rehabilitated.
Waterbird point counts
CDFW conducts a monthly waterbird point count survey, which is overseen by the FWS's Sonny Bono Salton Sea Refuge. There are set stopping points by vehicle around the Sea; CDFW covers the northern points and FWS cover the southern points. From these points binoculars and spotting scopes are used to count every waterbird seen from each point.
Yuma Clapper Rail and California Black Rail Surveys
Every year the Wister Unit of the Imperial Wildlife Area gets surveyed for Yuma clapper rails and California black rails as part of their requirement for their management plan. Wister has been recognized as one of five Areas of Utmost Importance for the Yuma clapper rail. Unlike other bird surveys, marsh birds are counted through marsh bird call-back surveys, which involves playing their calls and listening for them to call back. Besides Yuma clapper rails and California black rails, other birds are recorded, including least bitterns, American bitterns, Virginia rails, soras, common moorhens and pied-billed grebes.
The following links allow access to surveys, reports and other data collected on these species We hope you choose to learn more.