How To Disease-Proof Your Wild Bird Feeders

Feeding wild birds is a popular hobby globally, but it presents invisible disease risks to the very birds that we are feeding — but there are ways to safeguard their health.

Recently, the Royal Society for the Protection of Birds (RSPB) removed flat “table” bird feeders and associated items from its website sale offerings because the evidence suggests that this style of feeder may be helping spread fatal diseases amongst wild birds, especially finches. The most vulnerable are wild European greenfinches, Chloris chloris, which have been experiencing a severe population decline throughout the U.K. since the mid-2000s due to trichomonosis, a parasite that infects the tissues in a bird’s mouth, throat and esophagus, creating ulcers that make it difficult for the bird to eat and breathe. This nasty parasite, Trichomonas gallinae, spreads through saliva-contaminated water and seeds (ref) — but fortunately cannot infect humans.

“We know so many of you love feeding your garden birds and some bird species really do benefit from us putting out extra food for them, especially in winter,” the RSPB stated online. “However, there is increasing evidence that for other birds there can also be negative effects such as the spread of disease, especially among finches.”

“In light of this, we’ve taken the precaution of halting the sales of all our bird tables and associated items, table mix and table mix extra, window feeders and feeder guardians with trays. We’re doing this because evidence suggests birds, particularly finches, are at higher risk of disease if fed on flat surfaces.”

So what is a bird lover to do to keep their wild birds fed whilst also protecting them from deadly diseases?

To answer our bird feeding questions, I chatted in email with animal food supplier Richard Green from Kennedy Wild Bird Food & Pet Supplies, a family run business based in rural Lincolnshire. Mr Green answered my questions on how to protect “our” wild garden birds from any contagious illnesses that could kill them, especially during the harsh winter months.

Are some bird foods (dry seeds versus suet blocks, for example) more likely to spread illness amongst wild birds?

“Certain types of bird food can increase the risk of spreading illnesses among wild birds, especially if feeders aren’t cleaned regularly,” Mr Green replied.

“Black sunflower seeds in particular can leave husks that rot on the ground, making it easy for bacteria like Salmonella to grow. Other seed mixes with husks like canary seed and striped sunflower seeds can spread diseases if leftovers aren’t removed regularly,” Mr Green advised in email. “Use husk-free options such as sunflower hearts or specialised high-energy mixes instead to reduce the spread of diseases.”

How often should bird feeders be cleaned?

“Your bird feeder should be cleaned at least once every two weeks, but for feeders that are used more frequently, clean them after two to three seed refills,” Mr Green explained. “In wet or humid conditions, you may need to clean them even more often.”

How can one recognize a high-quality bird seed?

“Look for mixes that are rich in oil, which provide important nutrients for birds. If the seed looks old, has an odd smell, or even contains pests, it’s likely not the best choice.”

“Poor quality bird food can include peanuts or corn in the mix that sometimes contain harmful moulds which produce a toxin called Aflatoxin that can be deadly to birds, making it incredibly important to buy high-quality bird feed,” Mr Green cautioned.

“High-quality bird seed should be fresh, harvested from the current season, and free from pesticides and genetically modified ingredients,” Mr Green continued. “The best seeds won’t contain unnecessary fillers that birds don’t need, like wheat or barley and will be stored properly to avoid moisture and contaminants.”

How can people identify potential seed contamination?

“Bird food that appears shrivelled, unusually dark, or has a dusty coating may be a sign of contamination and should be avoided as these low-quality seeds are more likely to carry harmful bacteria or moulds,” Mr Green advised in email.

Are some birds (ground-feeding species, for example) more likely to become infected than others?

“Certain birds such as Greenfinches, Chaffinches, Siskins, House Sparrows, and Collared Doves, are often more vulnerable to diseases,” Mr Green replied. “This is mainly because of their social nature and tendency to feed in flocks, which increases close contact and makes it easier for illnesses to spread.”

Suet — either store-bought or home-made — is a common item to feed to wild birds. What can you tell us about how to correctly handle suet as a bird food?

“Raw suet should only be offered in winter, as it becomes rancid quickly in warmer weather and can soften, coating birds’ feathers,” Mr Green responded. “This is particularly dangerous during nesting season, as clogged eggshell pores can prevent embryos from developing properly.”

Some people do feed suet year-round. What tips can you share about how to do this safely?

“For year-round feeding, rendered suet or suet cakes are a safer option, but care is still needed as suet cakes containing ingredients like corn or peanuts can increase the growth of harmful bacteria if not handled properly,” Mr Green responded. “To avoid these issues, make sure suet cakes are purchased from reputable brands and store them in the refrigerator until use.”

I freeze my suet balls until I feed them to my birds. I assume this is fine?

“Freezing suet balls is fine as it can help preserve them for a longer period of time, keeping the suet fresh until you’re ready to use it,” Mr Green continued. “It’s a good idea to let the suet balls thaw out before placing them in bird feeders so that they are easier for the birds to peck at.”

Live mealworms are popular items to feed to wild birds. Are live mealworms more (or less) likely to spread diseases amongst wild birds?

“Live mealworms are generally safe to feed birds and are less likely to spread diseases because they have a vegetarian diet. Unlike meat-based foods, they don’t carry harmful bacteria that could make birds sick.”

“Mealworms are also packed with important protein, making them a great food choice for birds, especially during breeding season,” Mr Green pointed out in email. “Make sure you store them properly by keeping them at the right temperature and providing them with enough food so that they stay healthy and safe for feeding.”

Live mealworms are usually available for purchase from most pet shops or online, and can be refrigerated in the dark in a plastic container with a bedding of dry oats for up to 2 weeks. The cold slows larval development so they won’t transform into the adult darkling beetles. Mealworms can be fed slices of sweet potato or carrots to keep them hydrated and healthy, although they won’t consume much if they are refrigerated.

Last but not least, is water. Although some people do not provide water to their birds, they certainly do need it, regardless of the weather. How often should a bird bath or other water source be cleaned to prevent diseases?

“Water containers should be rinsed out daily, particularly in warmer weather, and allowed to dry before refilling,” Mr Green replied. “Similarly, bird baths should have fresh water added each day.”

A good scrub brush with stiff bristles can be an invaluable aid for cleaning a bird bath.

When feeding wild birds, it is important to monitor their overall health — subtle changes in their behavior, sitting motionless or fluffed, for example, indicates they are ill. If your birds are ill, immediately remove your bird feeders, and discard all food so the birds cannot access it. Also be sure to rake up all discarded seeds and husks under the feeding station and thoroughly scrub and disinfect all equipment and allow everything to dry before restocking your feeding station.

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