What not to feed wild birds: 8 things to avoid in your backyard

Our top tips on what not to feed wild birds this season

Dove eating bread in an urban garden hanging basket
(Image credit: Richard van der Spuy / Alamy Stock Photo)

Knowing what not to feed wild birds is important, particularly if you're building up your wildlife garden ideas at home. 

While there are plenty of kitchen scraps that birds will happily eat, there are some particular ingredients you should leave out. Some unexpected foods like onions, garlic, salt, and cooked oats all pose significant problems if a bird ends up eating them.

So, before you tip out your unfinished breakfast onto the bird table, have a read of the following to keep your visiting feathered friends happy and healthy.

What not to feed wild birds in your backyard

From alliums to chocolate, if you're trying to attract birds to your garden, here are the most commonly-found foods that you should avoid feeding them.

1. Salted and dry roasted nuts

Salted food in any form is a no-no for putting out on your bird feeder. This is because garden birds are unable to metabolize salt, which means even small amounts of it can be damaging to their nervous system.

This includes salted and dry roasted nuts – avoid making a common bird feeding mistake by choosing plain nuts instead. 

Top tip: The RSPB (opens in new tab) suggests ensuring that your bird-feeder peanuts come from a reputable seller who can guarantee they are free from aflatoxin, a fungal growth that can kill birds.

a common garden bird hanging and feeding on a bird feeder

Salted nuts are near impossible for birds to metabolize

(Image credit: Matt Limb OBE / Alamy Stock Photo)

2. Dairy products 

The lactose present in many dairy products poses significant problems. A bird's gut is unable to digest the lactose as birds don't have the lactase enzyme, which means they get upset stomachs.

However, birds can digest dairy products that have been fermented, which includes mild and hard cheeses. This is because fermentation decreases the level of lactose in the food.

bird eating lumps of cheese at garden birdtable

Birds don't do well with the lactose in dairy

(Image credit: Malcolm Schuyl / Alamy Stock Photo)

3. Bread

Bread is actually a safe enough food for birds to eat, seeing as it won't harm them – it's just that there's barely any nutritional value to it. The RSPB highlights that feeding birds with large amounts of bread fills them up without giving them the proteins and fats they need. As such, you should only offer bread in small quantities, and make sure it's alongside seeds and fruits that will benefit them.

Feeding birds moldy bread can be harmful, though, so if you've been throwing your green-speckled bread heels out into the yard, it's time to reconsider. Add them to your compost heap instead.

Bird eating bread in an urban garden

Bread is a nutrient-deficient food for birds

(Image credit: Richard van der Spuy / Alamy Stock Photo)

4. Cooking fats 

Hard fats such as lard and suet are full of energy and are particularly good for feeding birds in winter. You can even make bird feeders yourself using them as ingredients.

But, the RSPB explains that the runnier fats, like cooking oil and meat drippings, tend to smear once they've set. This smearing can damage the waterproofing and insulating properties of birds' feathers. 

Additionally, there can be salt from the cooked meat present in the fat which, as covered above, isn't good for birds. 

Vegetable oils and butter are also a bad idea for birds for the same reasons. 

A Robin visiting a garden feeder for a fat ball in winter

Stick to hard fats for your bird feeders

(Image credit: Paul Melling / Alamy Stock Photo)

5. Fruit with seeds and pips

Although we think of birds and seeds as a match made in heaven, it's actually not the best idea – with some types of seeds, that is. Most fruits are perfectly safe for birds to eat, but there are some with seeds, pips and pits that should be avoided where possible. This is because the seeds contain traces of cyanide which is toxic to birds. 

Remove the seeds of apples and pears before putting them on your bird table (you could try planting the apple seeds if you wish). Pitted fruits like cherries, peaches, plums and apricots should also have their stones removed before being available to birds.

Bird perched on an apple

The cyanide present in some fruit seeds and pits is toxic to birds

(Image credit: Juniors Bildarchiv GmbH / Alamy Stock Photo)

6. Alliums (onion, garlic, scallions)

Alliums like onions, garlic, scallions and leeks are all a problem for birds. Like fruit seeds, these foods can be toxic when ingested in high volumes, causing irritation and even hemolytic anemia in birds. 

As it's only the ingesting that's an issue, growing garlic is often used as a bird repellent due to the strong odor it naturally emits. The smell isn't harmful but birds find it unpleasant, meaning they stay away from nearby plants and vegetables.

Great tit at a bird feeder in the garden in the winter

Check your bird food for onions and garlic

(Image credit: Lars Johansson / Alamy Stock Photo)

7. Chocolate

It may not be on your bird food list, but chocolate is commonly fed to birds – and it shouldn't be. The darker and more bitter the chocolate is, the higher the chances of toxicity for pets and small animals, thanks to the caffeine and theobromine present. This can cause diarrhea, seizures, vomiting and hyperactivity, and in big enough doses, can even cause death. 

By association, anything with coffee in it – coffee beans, coffee grounds, tea, caffeinated sodas and coffee-flavored foods – should also be kept away from birds. 

A male Siskin (Carduelis spinus) perched on a bird feeder eating seeds

The theobromine in chocolate makes it unsuitable for birds

(Image credit: Toby Houlton / Alamy Stock Photo)

8. Cooked porridge oats

It's an easy enough decision to scrape your leftover porridge oats onto the bird table, but the cooking process means oats become sticky and thick. This can easily gum up a bird's beak and cause lots of problems. 

In contrast, dried oats are a perfectly acceptable food option for birds.

male spotted woodpecker at a bird feeder with peanut butter

Be careful not to cause problems for birds with cooked oats

(Image credit: blickwinkel / Alamy Stock Photo)

Now you know what not to feed wild birds, you can try these options which are much better for them instead:

The RSPB also highlights that you need to store your bird food properly. If it has started to go moldy and spoil, this is harmful to birds and the associated bacteria may spread diseases. As a result, it’s best to store food in airtight containers.