Salmonellosis is a fatal bacterial infection that rapidly spreads through populations of wild birds via feces-contaminated food and water. Most often, Salmonellosis Outbreaks originate where birds flock to feeders or baths. Infected individuals will appear lethargic, puffed/fluff-up, with eyes partially closed; on occasion, eyes may also appear swollen, red, or irritated.
Pine Siskins – tiny, heavily streaked, yellow-accented finches – are especially susceptible to Salmonellosis. Pine Siskins occur naturally in small populations across Sonoma County; however, some winters we see huge numbers migrating in. This mass-migration is referred to as an “Irruption Year”, a natural phenomenon driven by fluctuations of available resources. There are shortages of tree seeds across Canada’s boreal forest (the normal wintering grounds for Pine Siskins), causing siskins to ‘irrupt’ south in search of food.
Not only are Pine Siskins especially susceptible to the disease, they are also carriers of Salmonellosis, spreading it throughout the environment. Therefore, we often see Salmonellosis Outbreaks correlated with irruption years. If the disease persists in the environment for long enough, it will eventually spread from Pine Siskins to goldfinches, other finch species, and beyond, penetrating deep into the avian community.
Risk of Salmonellosis to Humans and Domestic Animals
Salmonellosis is a zoonotic disease, meaning it can be transferred from animals to humans, and vice versa. In avian species, Salmonellosis is often fatal; however, in mammalian species, such as ourselves and our 4-legged companions, Salmonellosis often presents as “food poisoning”. Common symptoms include acute abdominal pain, diarrhea (sometimes containing blood), vomiting, weight loss, or fever. Severity of symptoms can vary widely, but humans/mammals infected with the disease may not get sick at all and/or many that do become symptomatic will require no medical treatment beyond rest and hydration.
If you find a sick bird, please do not hesitate to help it! If you are diligent about washing your hands after you capture the animal and/or handle potentially contaminated equipment, there is a very small risk of infection. Additionally, the use of small latex-style disposable gloves can be worn to eliminate direct contact.
That said, parents of young children and/or owners of free-roaming cats or outdoor dogs, please take note. Your loved ones are at risk of contracting Salmonellosis if they have free access to potentially infected equipment (i.e., feeders and baths) or dropped seeds. Furthermore, pets – primarily free-roaming cats – that predate upon infected wild birds can contract the bacteria. These are some of many good reasons to always keep your cats indoors or contained in a catio, as well as to follow our recommendation of fully removing your feeders and baths if you find a sick bird in your yard. Your local wildlife, pets, and loved ones will thank you for keeping their safety in mind!