I have received a few reports of sick and dying Common Redpolls at bird feeders around the region. In the past when I have seen this I have sent samples for testing and they have come back positive for Salmonella. Have you cleaned your feeders lately? With warming spring temperatures its time to clean bird feeders with a 10% bleach solution and rake up all the seed waste that may be on the ground around them and dispose of it.
Redpolls come from the far north where they may not be exposed to pathogens common in our year-round backyard birds. Salmonella is commonly isolated from House Sparrows for example. They also congregate in large numbers around a concentrated food source and come into contact with infected droppings. The warmer spring temperatures and old seed on ground probably increases transmission.
Salmonellos is caused by a bacteria belonging to the genus Salmonella. It is a common cause of mortality in feeder birds, but the symptoms are not always obvious. Sick birds may appear thin, fluffed up, and may have swollen eyelids. They are often lethargic and easy to approach. Some infected birds may show no outward symptoms but are carriers of the disease and can spread the infection to other birds.
It is primarily transmitted by fecal contamination of food and water by sick birds, though it can also be transmitted by bird-to-bird contact. Occasionally, outbreaks of the disease cause significant mortality in certain species. It only takes a few minutes to wash your feeders. Take some time and do it today!