Native Bird Care is getting a lot of calls about sick and dying birds at feeders this winter. These birds are mainly Pine Siskins, but also Evening Grosbeaks, Goldfinches, and other finch family birds. Sadly, they are suffering from Salmonella, which is a highly contagious bacterial infection.
You can do a lot to help slow down this disease and protect your birds with the right feeders and cleaning practices. Please explore the instructions below for specific details on how to help your birds.
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Pine Siskins are particularly susceptible to Salmonella infection. These birds are experiencing what is called an "irruption" year, which is when an unusually large number of a species appear in areas further outside of their range. We have local Pine Siskins throughout the Northwest, however, these birds are most common across Canada, residing in the expansive boreal forests. Unfortunately, a shortage of conifer seeds has forced thousands of these birds to head south. Notably, people from across the country and even Florida are seeing these sweet little birds. (Audubon has a nice article on this irruption).
Birds share disease wherever they congregate and avian scientists confirm that bird feeders are a location in which disease can be passed to other birds (Adelman et al. 2015; Dhondt et al. 2007; Galbraith et al. 2017; Hernandez et al. 2012, Lawson et al. 2018). But any location in which birds hang together, such as a communal roost, are places for infections to spread. Salmonella is just one of several pathogens that can be spread at the bird buffet. Others are: conjunctivitis, avian pox, aspergillosis, trichomoniasis, and coccidia, along with internal parasites, mites, and feather lice.
However, not ALL birds carry these pathogens (just like not all people carry the cold virus). In fact, studies show that only a few birds actually carry the Salmonella bacteria. This bacteria, though, is highly contagious, and one reason it is is the length of time it can survive in the environment (say a bird feeder). The FDA reports that Salmonella can, "survive several weeks in dry environments and several months in wet environments." In contrast, Conjunctivitis survives from "hours to a few days" according to Dr. Wesley Hochachka of Cornell Lab of Ornithology. The good news is that we can play a key role in reducing the number of pathogens that might be congregating at our feeders simply by regularly cleaning them.
You might wonder why the Pine Siskins are ill, while the Chickadees and Nuthatches are seemingly fine. For some reason, unknown at this time, some species are just more susceptible. The finch family of birds seems to be more susceptible to both Salmonella and Conjunctivitis. This family includes Pine Siskin, House Finch, Evening Grosbeak, Red Crossbill, and the Goldfinches. But, any bird or mammal can acquire this sometimes fatal infection. Raptors and Owls that prey on birds can get sick, doves, pigeons, and chickens too are susceptible. (Notably, this disease spread from agricultural poultry farms, and more birds who congregate near agricultural animals carry the infection).
A few birds will carry the bacteria in their guts, without visible external symptoms.
Stress makes animals more susceptible to pathogens of all kinds, from worms to disease. So birds who are experiencing a lack of food and are forced to migrate long distances to find it, are very stressed, and frankly, many may be starving. This is why some of the Pine Siskins act aggressively at the feeder. They literally are fighting for their lives. (They are not 'mean', they are actually a sweet species). This stress can launch an active infection, and that can spread to their flock mates.
The bacteria spreads by fecal matter or saliva. So, if they are feeding where they relieve themselves, this is a huge problem. Any feeder in which a bird is able to sit in their food is a potential source for infection. Flat feeders and those with large seed catchers are primary culprits. Feeders that can collect poop, also collect the bacteria, increasing birds' exposure. A bird that can sit with their little pooper in the tray, is a bird that is pooping where they are eating. (You can trim off seed catchers on mesh feeders, just do not leave a sharp edge!).
Salmonella causes lesions and inflammation throughout the digestive track and esophagus. It can enter the bloodstream and affect the organs and the brain. Once in the brain it causes cognitive impairment, which is why they act "tame" and you can get so close to an ill bird. Birds ultimately die from starvation, being unable to absorb the nutrients they need, or organ failure. Some birds are able to overcome the disease though and gain enough immunity to survive. Dr. Hochachka speculates that, "many other species are innately more able to fend off Salmonella infections," and develop immunity. However, given the death rate, it doesn't appear that this is happening for the Pine Siskin and Redpoll.
Our role in helping these birds is simple. We can create an environment in which the birds have a safe environment to feed.
Here are some helpful tips for keeping our birds healthy and happy!
Should I take my feeder down?
Wildlife vets and agencies recommend taking the feeders down during such severe outbreaks. Leaving the feeder up and NOT following strict cleaning practices will cause more birds to die. Also, leaving feeders up that are known disease spreaders, will also lead to more death.
Whether leaving the feeder up is a good or bad idea is a complex question. There are numerous interwoven elements. Removing feeders might allow the birds to disperse, if there are no other nearby feeders for them to go to. Or, if there are, the competition for the feeder is high enough to force the birds to move on.
Removing feeders may result in sick birds staying nearby as they may lack the energy to fly very far. This will keep them from exposing another feeder. Birds can also seek out wild food sources and if sick, perish.
Many people will chose to leave their feeders up thinking that the feeder is doing more good than harm. With Conjunctivitis, some scientists make an argument for feeding ill birds because they are often starving and some can develop immunity. Birds with Salmonella are also often starving, however, Pine Siskins do not generally survive and leaving the feeder up allows them to continue to sit in a feeder.
It's clear that when only a few feeders are removed in a feeding area, many birds will simply go to another feeder. This can concentrate more birds into fewer feeding areas and feeders. Thus, increasing bacterial load for all birds. If you live in an area experiencing winter storms, you will have to weigh the true benefit of the feeder being up versus coming down.
Regardless, if you leave feeders up during an outbreak, whether you are seeing ill birds or not, you must increase your cleaning practices and spread the feeders out.
Our outbreak recommendations:
Remember: many birds are asymptomatic. We do not see most sick birds because they move into the canopy. Just because you do not see suffering birds does not mean your birds are not sick or at risk.
Best Practices Feeder Tips:
Clean up all debris from under feeders
Salmonella Symptoms: What do I look for?
How do birds get the infection?
Salmonella is passed through a bird's droppings and saliva. At feeders, birds' droppings and saliva can get onto parts of the feeder or on the food itself as they feed. Is spreads when another eats contaminated seeds or pokes around in the debris under the feeder where others have left feces. This infection is also spread when one animal scavenges on another. So, crows, gulls, and other common omnivore scavengers (including raptors) can contract and spread the infection. It is spread through waterways as well.
Which species get the infection most?
The finch family is known to be the most susceptible to the finch form of this infection. The finch family includes: goldfinches (lesser and American); house, purple, and Cassin's finch; pine siskin; evening grosbeaks; black headed grosbeaks; and red crossbill. Other birds also get salmonella: mourning doves, starlings, blackbirds, gulls, the bird-eating raptors, crows, and others.
What do we do if we find a sick or dead bird?
Dead birds: use gloves to handle either sick or dead birds. Do not bury or leave dead birds out. Burying spreads the disease into the soil. Put dead birds into a plastic bag and dispose into trash.
Living, but sick birds: Take a hand towel and simply pick up the bird. You can also use a butterfly net. Use gloves or a towel. Place into a small box or paper bag, on paper towels. Never leave sick birds in your yard, not only are they spreading the disease, but they are suffering as well. Find a local songbird rehabilitator or call your local Fish and Wildlife agency.
Can humans or pets get Salmonella?
Yes, but it is not likely. The amounts in bird feces are tiny, and we are large. It would take a lot of feces or we would have to have a very weak immune system. Dogs and cats fend off salmonella all the time, but if they eat a sick or dead bird then they can possibly get ill. If you have outside cats, you should not feed birds anyway, but for sure you shouldn't feed when there is a disease spreading.
Chickens carry their own particular subspecies of salmonella. It too can be spread to wild birds. In fact, agricultural animal waste is one source of salmonella infection for wild birds, particularly those associated with those animals (starlings and house sparrows). Chickens and wild birds can contract each other's subspecies of the infection, but it is less common that we know of. Chickens come with a host of other infectious diseases that affect our wild birds. Always ensure that wild birds cannot get into the chickens enclosures.
Please use common sense when handling sick or dead birds, and when cleaning your feeders and baths. Gloves are mandatory.
If you would like citations for the research mentioned, email us at firstname.lastname@example.org
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