Please be cautious when serving fats to birds. Fats and oils can ruin feathers' weatherproofing and insulating properties. 

Birds are marvels of nature, but even they can be misled into making poor feeding choices. In winter, birds need calorically dense foods to meet their metabolic needs. We can support some birds by offering safe fats, like suet and peanut butter, during hard spells. However, birds rely on their feathers for critical functions like insulation, waterproofing, and flight. 

But did you know that fats can pose a deadly risk to their survival? Here’s why understanding the impact of fats on birds’ feathers is essential, especially if you enjoy feeding backyard birds.

Why Fats Are Dangerous for Birds
Fats disrupt the delicate structure of a bird’s feathers, compromising their ability to insulate and repel water. This is similar to how oil spills devastate aquatic birds—we’ve all seen those heartbreaking images of birds coated in oil, struggling to stay warm and afloat. Even small amounts of fat can cause significant harm.

In winter, this loss of insulation can quickly lead to hypothermia, a life-threatening condition, and subsequent starvation. In summer, while hypothermia isn’t as immediate a concern, birds still rely on their feathers to maintain body temperature and protect against the elements. Healthy feathers are always a necessity.

How Birds Get Fat on Their Feathers
Birds can accidentally spread fats onto their feathers in several ways:

• Direct exposure: Landing on exposed fats, like suet balls, fat-covered pine cones, peanut butter-slathered trees, or feeders that allow the bird to get fat on their feet or directly onto feathers. 
• Preening and scratching: Fats can transfer from feet onto to birds' heads and bodies as they preen.
• Using their bills: Super soft fats left in or on the bill from feeding can spread to other feathers during preening.

The softer and greasier the fat, the more easily it spreads. Hard, dry, and crumbly fats are far less likely to stick to birds' feet and bills, making them a safer option for feeding. See discussion of safe fats below. 

The Deadly Consequences of Fat-Coated Feathers
Feathers act like a bird’s wetsuit, creating a protective barrier against cold air and water. They also retain warmth via air pockets held in by the birds' feathers (why birds fluff up on cold days). When fats or oils interfere with this barrier, the bird becomes vulnerable to the elements:

• Hypothermia: Even mild exposure to cold can be fatal if feathers lose their insulating properties and even a small amount of water or snow gets on the birds' skin. Water on the skin leaks warmth from the bird. 
• Starvation: Birds spend hours attempting to clean their feathers instead of foraging for food. Over time, they become too weak to survive.
• Stress and exhaustion: Larger birds may endure longer but eventually succumb to the compounded strain of shivering, preening, and insufficient nutrition.

Once fats compromise a bird’s feathers, the damage is irreversible without human intervention. Bird saliva and preening cannot remove oils. Soap is required, as it is when we get oils on our hands. Avian rehabilitators need specialized soaps and techniques to clean up greasy or oiled birds. 

How to Prevent Harm: Safe Suet Feeding Tips
Protecting birds starts with choosing the right suet and feeding practices:

• Use hard suet: Opt for dry and crumbly suet from the cow or pig loin area.
• Avoid soft, easily spread fats like vegetable, beef/pork fat, crisco
• Feed suet in a caged feeder: Prevent birds from landing directly on suet or any fat - reducing the risk of fats spreading. (Squirrel-proof feeders are best).
• Avoid exposed suet balls, wreaths, or cakes: These allow too much direct contact, increasing the likelihood of greasy feathers.
• Never use fat-slathered pine cones - anything that allows the bird to land on the fat. 
• Never put peanut butter or any fats directly on trees or their branches - this does not happen in nature, and birds do not understand the risks. 

Greasy birds are rarely found. Like many birds with injuries, they will hide somewhere out of sight as they attempt to correct the problem. Rescues get these birds only if they are found in a near-death condition. 

Feeder Tips

• Log feeders work if they have a perch - drill a hole and put in a chopstick or small dowel.
• Wreathes are easily made using gelatin rather than fats.
• Squirrel-proof feeders with a cage around the suet cake holder allow birds to feed with little risk of contamination.
• Keep suet feeders clean by frequently washing in hot water and soap. 
  
  

How & When to Feed

• Fall, winter, and spring are the main suet feeding times.
• Migrants might enjoy suet in September and October. 
• Never over 80 degrees.
• Do not place suet directly in the sun, unless it is below freezing. Then watch for melt, as even winter sun gets hot.
• Shaded areas are better than direct sun.
• All fat can go rancid. Toss the cakes after a week unless it is freezing. 
• Dispose of any fats in the garbage, do not leave fats out in the yard.
• If no one is eating it, reconsider your recipe.  

Choosing the Right Fats for Birds:
The type of fat you feed birds matters. Soft fats with low melt points, like vegetable oils and non-suet beef fat, can easily spread onto feathers. Hard fats, such as true suet and peanut butter, are safer and provide better nutrition. (Butchers' fats and tubbed fats can be mislabeled as "suet" when they are not). Rendering does not always result in a hard fat. 

What Is True Suet? 
True suet is the hard, crumbly fat around a cow's loins and kidneys. It:

• Has a high melt point (113°F or higher), resisting spread.
• Provides birds with concentrated energy and calories.
  
• Peanut butter is a good source of fat with a high melt point
  
• Peanut butter must be fed as described above as well. 
  
  

Not suet: Bacon grease, cooking drippings, vegetable oils, and other fats that require fillers like flour to hold shape.

Soft Fats Are Risky
​Soft fats (melt points as low as 75°F):

• Spread easily, harming feathers.
• Get soft or melt even in winter in direct sun. 
• Offer poor nutrition due to fillers (flour, corn).
• Force birds to eat more, work harder, and risk deficiencies.
  
  

Peanut Butter
Peanut butter (melt point 104°F) is a safer alternative. Look for PB with no added oils or sugars, and consider mixing it with suet for a "no-melt" option.

Test Your Suet Cake 

• Squishy? Toss it—too soft.
• Does the suet cake feel greasy? 
• Crumbly and dry? That’s true suet.
  
  

Avoid cheap, filler-heavy suet cakes that compromise bird safety and nutrition. Choose high-quality fats to support your feathered friends!
​
Simple Suet Recipe
Mix peanut butter (no sugar) and true suet one to one. Add quick oat or wheat flour if you want to, but not much. Add shelled seeds, nuts, and fruit. 

See Bird-Safe Wreaths for how to make fun bird-friendly crafts for kids and adults. 
​

Follow these handy tips for dealing with sick or dead birds at the feeder. 

Sick birds are still showing up at feeders all across the country. Mainly these are Pine Siskins ill with Salmonella, a bacterial infection. 

Salmonella can be passed to baby birds from their parents. The species most vulnerable are the smaller finches, like pine siskin and goldfinch, but red crossbills and other birds can also get this disease. 

Salmonella spread is stopped through disinfecting or removing feeders, and using feeders that are less likely to spread disease. Note that contamination happens as soon as a sick bird lands on a feeder.

Basics and Instructions for Cleaning, Feeder Suggestions:

*1) If you have a sick bird - remove the feeders for a week or two. Take found sick birds to a rescue. 

*2) If you have had sick birds, switch to feeders less likely to spread disease - mesh hanging types or hoppers with very narrow feeding trough. Remove feeders that allow a bird to poop into the food! Isolate species by feeding foods specific for the species, see below. 

*Continue feeding ONLY if you are able/willing to keep the feeders cleaned and disinfected, and able to do this frequently. Fecal matter and saliva are how this disease is spread. Salmonella survives freezing, and hot temps, and lasts a long time in the environment. Bleach is necessary (not vinegar!). Instructions below. 

*If you are seeing more than one or two sick birds, please change your feeders as they are likely spreading disease. See below. 

Please explore the instructions below. 

​Signs of Salmonella: Symptoms: Main sign is a bird sitting listless and not moving. Salmonella causes lesions and inflammation through the digestive track and esophagus.

It enters the bloodstream and then organs and brain. Once in the brain it causes mental issues, which is why sick birds act "tame" and they do not fly away. Birds ultimately die from either starvation, since salmonella lesions impair digestion, or organ failure. 

1. Sick birds act lethargic (tired)
2. Will sit a lot either at the feeder or on the ground.
3. They are often fluffed up. 
4. Will act tame or tolerant of your approach.
5. Eyes may be partially or fully closed, may have some redness.
6. May be drooling or have signs of vomit.
7. Might have head tucked under wing in broad daylight. 
8. Easily confused with a bird in shock from hitting a window.

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 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, they are suffering, and spreading the disease.
• 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. Cats that eat birds can and do get it. But if you have outside cats, you shouldn't be feeding birds. 

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). 

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 [email protected]