Fat Balls for Birds: Nets, Holders and Safe Feeding

Fat balls for birds are safe and useful in cold weather, as long as you take them out of the plastic net, hang them in a metal holder and swap them before the fat turns rancid. Tits, sparrows, starlings and woodpeckers take them most. In warm weather, follow your national bird charity’s season rule, because soft fat spoils fast.

Fat balls (US readers usually call them suet balls) are fist-sized balls of hard fat packed with seeds, oats or insects. They’re cheap, sold everywhere from garden centres to supermarkets, and often still come wrapped in a green plastic net. That net is the first thing to deal with.

This guide covers how to feed fat balls safely. If you’d rather make your own, see our homemade suet recipes. If you’re choosing a product, our suet comparison covers that.

Are fat ball nets dangerous to birds?

Yes. The RSPB, NABU and Vogelbescherming all say to remove them. The RSPB is blunt: “Never put out any food in mesh bags. These may trap birds’ feet and even cause broken feet and legs.” It adds that birds with a barbed tongue, like woodpeckers, can become trapped by their beaks.

The same advice comes from the national bird societies across the Channel:

• NABU (Germany) asks people not to use fat balls in plastic nets, because birds get tangled and injured in them too often.
• Vogelbescherming Nederland lists “no fat balls or peanuts in a (plastic) net” on its do-not-feed list, because birds can get caught and the nets end up as litter.
• Natagora (Belgium), quoted by the broadcaster RTBF, says there’s no scientific study counting the birds that die this way, but that it does happen.

That last point matters. Nobody has a reliable figure for how many birds are hurt by nets, so be wary of any page that quotes one. What’s clear is that the risk is avoidable, and every source agrees on the fix.

Many fat balls are now sold without nets, often in a tub or bucket. If yours came netted, cut the net off with scissors before you hang the ball, and put the net in the bin so it can’t blow into a hedge.

Net, no net or holder: what should you do?

Here’s the decision table we built from the RSPB, NABU and Vogelbescherming advice. Find your situation and follow the right-hand column.

A metal holder is different from a mesh bag. When the RSPB recommends “a hanging mesh feeder with fat balls” for tits, sparrows and starlings, it means a rigid wire feeder, not the soft nylon net the balls are sold in. For holder types, see our guide to suet feeders.

Which holders work without a net?

Any rigid holder that lets birds cling without anything soft to snag on. This table pulls together what the RSPB, BTO, NABU, Vogelbescherming and the Cornell Lab say about each option.

Whichever you choose, clean it as part of your weekly routine. The Cornell Lab suggests a hot dishwasher cycle, soap and boiling water, or a bleach solution of no more than 1 part bleach to 9 parts water with a 10-minute soak, then a thorough rinse and full drying. Our comparison of suet and fat ball feeders covers holder designs in more detail.

How do you feed fat balls safely?

Hang them in a rigid holder, in the right spot, and keep the station clean. Most problems come from where the food sits and how long it stays there.

Use the right holder

A wire cage, a mesh tube made of metal or a spiral holder lets birds cling and peck without anything to snag on. Tits love hanging food: the LBV notes that all tit species prefer it, because hardly any other birds can use it as well as they can. That means a hanging holder also keeps much of the fat for the small birds.

Hang it in the right place

The RSPB advises placing feeders high enough to be out of reach of cats, and a couple of metres from thick cover so small birds can escape a sparrowhawk. Avoid hanging them under places where birds perch, so droppings don’t land on the food.

Windows are the other hazard. Vogelbescherming Nederland says the risk of window strikes is highest when food hangs 5 to 10 metres from a window, so hang it closer than 5 metres or further than 10. Our guide on where to put a bird feeder goes into more detail.

Keep it clean

Dirty feeding stations spread disease. The RSPB recommends washing feeders every week with a mild disinfectant and hot water, then rinsing and drying them before refilling. It also suggests moving feeders, ideally weekly, so debris doesn’t build up underneath. NABU adds two simple habits: wear gloves and wash your hands afterwards. Our step-by-step guide covers how to clean a bird feeder.

Don’t overfeed

Put out only what birds will finish. The RSPB says food in feeders should be eaten within a day or two, and Vogelbescherming suggests amounts that are gone by evening. One or two balls at a time is plenty for most gardens.

How many fat balls should you put out?

Start with the one or two balls suggested above, then adjust to what your birds actually eat.

A fat ball holds a lot of energy for a small bird. The BTO says a blue tit of about 11 g needs roughly 1 kcal per gram of body weight per day, so about 11 kcal. Fat provides about 9 kcal per gram, according to the FAO’s standard conversion factors. Even if only 40 g of an 85 g ball were fat, that’s about 360 kcal, roughly a day’s energy for 30 blue tits. As a rough guide, a few tits can make one ball last several days, while a flock of starlings can clear it in a morning.

Can you feed fat balls in summer?

It depends on the weather and on where you live, because the national charities don’t agree. In hot weather, all of them would rather you didn’t leave soft fat hanging.

If you’re in the UK, the RSPB’s rule is the one to follow. In a hot spell, take fat balls in, whatever your country. For the full picture, see should you feed birds in summer.

How can you tell if fat balls have gone rancid?

Vogelbescherming Nederland gives three warning signs: the fat smells nasty, a black or white haze forms on the surface, or the seeds inside begin to sprout. It notes that fat balls and other fat products spoil faster in mild, wet weather.

If you see any of these, remove the ball, bin it and clean the holder. Better still, prevent it: buy only as many as you’ll use in a few weeks, store them somewhere cool, dry and rodent-proof (the RSPB suggests clean storage bins), and put out only what birds will eat quickly.

How should you store fat balls, especially in warm months?

Keep spare fat balls cool, dry, dark and sealed. The LPO advises storing them away from light and humidity, and in airtight containers to stop insects getting in.

Warmth is the main enemy. The Cornell Lab explains that raw suet goes rancid quickly once temperatures are above freezing, while rendered fat keeps better but can still soften in warm weather. Softened fat can coat a bird’s belly feathers, which Cornell says is dangerous for birds sitting on eggs.

Which birds eat fat balls?

Tits are the regulars, but a surprising mix of species will take fat. This table combines what the RSPB in the UK and the LBV in Bavaria say about who feeds on fat.

Robins, dunnocks and blackbirds are mostly soft-food eaters that feed on the ground, according to NABU and the LBV. Vogelbescherming suggests cutting cooled fat into small pieces so birds that don’t normally sit on a fat ball can eat it too. Clear up any leftovers by evening.

What should you check on the label?

Look at the fat, the filler and the packaging. You can’t see much through a net, so the label is your best guide.

• No net. Pick balls sold loose in a tub or box. It’s the simplest way to avoid the problem.
• No palm oil. The LPO lists fat balls without palm oil among the foods you can give. Vogelbescherming’s own recipe also specifies fat without palm oil.
• No salt. Salted fat, bacon fat and meat scraps are on every charity’s avoid list. The LPO names salted lard and meat fat specifically.
• Few fillers. The LBV warns that many suppliers stretch bird food with fillers that birds don’t eat, which then pile up under the feeder. A short ingredient list of fat, seeds, oats or insects is a good sign.
• Melt-resistant for warm months. If you feed outside winter in the UK, the RSPB advises choosing products that state they resist melting.

Avoid butter and margarine too. Vogelbescherming says they act as a laxative in birds, and the LBV lists pure fat such as butter or margarine as something not to feed.

What’s actually in a fat ball?

Under EU feed-labelling rules, which Great Britain kept as retained law, the ingredients of compound feed such as fat balls must be listed in descending order by weight. Percentages are optional, except that any ingredient the pack emphasises in words or pictures, such as “with mealworms”, must have its percentage shown.

There’s a catch for bird food. For feed meant for animals that aren’t kept for food, the same regulation lets makers use a category name instead of the specific ingredient. A label that just says “oils and fats” doesn’t tell you whether palm fat is inside, so look for an explicit “no palm oil” statement.

A real example shows why order matters. The LPO’s own insect fat balls weigh 85 g each and list wheat flour first and tallow second, with 2% dried mealworms declared. Because flour comes first, the tallow can’t make up more than half the ball.

Why avoid palm fat? The LPO advises plant fats, ideally rapeseed-based, or beef tallow, and never palm oil. The wider concern is deforestation: palm oil is one of the commodities covered by the EU regulation on deforestation-free products. The RSPB lists lard and beef suet among suitable foods.

Is fat bad for tits? What the research says

Not in a way that should stop you feeding in a cold garden, but the evidence is mixed. The BTO has reviewed the studies and concludes that it’s hard to argue people should stop providing fat-based foods in their gardens. All of the research so far was done in woodland, not gardens.

What the woodland studies found, according to the BTO:

• Blue and great tits fed peanut cake (50% beef suet), and blue tits fed vegetable fat, produced fewer young than unfed birds.
• In a study by Plummer and colleagues (2013), blue tits fed fat balls in winter raised chicks the next spring that were smaller, lighter and less likely to fledge.
• Great spotted woodpeckers fed suet did better, with higher productivity.

What nobody has measured yet is whether fat helps tits survive autumn and winter, which could outweigh the effect on breeding. The practical reading: feed fat in the cold months when it does the most good, keep it fresh, and offer a variety of foods rather than fat alone. For the bigger picture, see do birds become dependent on feeders?

What to do next

Fat balls are one of the easiest ways to help garden birds through a cold spell, once the net is gone. Hang them in a metal holder, keep the station clean, swap any ball that smells off, and follow your local season rule.

Want more options? Read what to feed birds in winter for the full menu, try one of the homemade recipes linked above, or compare ready-made blocks in our best suet for birds guide.

Sources

• RSPB: How and what to feed your garden birds
• NABU: Vögel richtig füttern
• LBV: Welcher Vogel mag welches Futter?
• LPO: Quand nourrir les oiseaux ?
• Vogelbescherming Nederland: Wat is goed voer?
• Vogelbescherming Nederland: Hygiënisch vogels bijvoeren, 6 tips
• BTO: Keeping warm on winter nights
• BTO: Are fatty foods bad for birds?
• BTO: Winter food provisioning reduces future breeding performance in a wild bird (Plummer et al. 2013)
• FAO: Food energy, methods of analysis and conversion factors
• Regulation (EC) No 767/2009 on feed marketing and labelling, Article 17 (legislation.gov.uk)
• European Commission, Access2Markets: EU deforestation regulation
• LPO boutique: fat balls with insects, product sheet (French)
• LPO: Nourrir les oiseaux de son jardin en hiver (French)
• Cornell Lab, All About Birds: About suet, mealworms, and other bird foods
• Cornell Lab, All About Birds: How to clean your bird feeder
• NABU Niedersachsen: Futterknödel für Wintervögel (German)
• Vogelbescherming Nederland: Zelf een vetbol maken in 6 stappen (Dutch)