Why Are These 10 Foods Unsafe For Wild Birds?

As more and more people feed birds in their backyards, the chances of feeding them the wrong food types increase.

There are many articles on the internet about what food should not be offered to birds. Much of this information is repeated across articles and refers to cage or pet birds, not wild backyard birds.

Some of 10 food items listed below can be harmful to birds if they are ingested in unrealistic high amounts. Additionally, common sense tells us that backyard birds wouldn’t have access to some of these foods, and most wouldn’t eat them. 

Crows, pigeons, grackles, starlings, and house sparrows eat a wide range of food types and more likely to ingest food regarded as “unsafe for birds.” 

1. Fruit pits and apple seeds

The detrimental effect of apple and pear seed on birds is relative and is nearly a myth widely repeated on the internet.

Indeed, the seeds of apple, pears, cherries, plums, peaches, nectarines, and mangoes contain cyanide. 

In small quantities, apple seeds do not contain enough cyanide to harm humans nor birds. 

A human of average size would need to consume a few hundred to a thousand crushed apple seeds to be poisoned by cyanide.

Ingesting many whole apple or pear seeds would not have any effect on humans because these seeds have an outer layer resistant to digestive juices. These seeds pass through our stomachs whole. 

Cage bird breeders estimated that a cockatiel ( a  parakeet weighing approximately 2.5 to 4.2 oz) would have to eat 40 to 60 crushed apple or pear seeds on a single sitting to experience cyanide damage and possibly death. 

Backyard birds would need to eat many crushed apple or pear seeds to be affected by cyanide. However, it is better to remove the seeds and offer just the fruit to your feathered friends.

2. Onions, chives, and garlic

As with apple seeds, onions, garlic, and chives can be harmful to birds when ingested in substantial amounts.

The anti-inflammatory compounds and antioxidants in onions, chives, and garlic may reduce the risk of high blood pressure and heart disease in humans. The anti-inflammatory properties of these plants may also protect against blood clots.

Onions, garlic, and chives are toxic to dogs and cats that consume them in excess. The toxic principle in these plants, N-propyl disulfide, causes red blood cell breakdown, resulting in anemia.

According to dog breeders, the amount of onions or garlic needed to make a 30-pound dog sick is approximately 2.5 ounces. 

Based on what makes a dog ill, we can assume that a bird would need to ingest a proportionally large amount of onions, chives, or garlic to become sick. 

If some onions were overlooked in the kitchen scraps we provide to our backyard birds, they would not be harmed. However, if possible, we should avoid offering birds onions, chives, and garlic from kitchen scraps.

Related: The 14 Most Popular Foods for Backyard Birds (with Pictures and Facts)

3. Avocado

Avocado is praised as a quality food for humans. Wild avocados, a tiny version of the ones sold in the supermarket, are a superfood food for tropical birds such as Quetzals, trogons, bellbirds, and other frugivores (fruit-eating) birds. 

The bad reputation of avocado as bad food for birds comes from the fact that avocado has persin, a fungicidal toxin.

Persin is present in a tiny amount in the pulp, skin, and pit of the avocado.

But the leaves and bark of the avocado tree have much higher concentrations of persin.

Persin can cause increased heart rate, myocardial tissue damage, labored breathing, disordered plumage, unrest, weakness, and apathy in birds and small mammals. 

Interestingly, persin is not harmful to humans and is even being investigated as a treatment for breast cancer. It has also been shown in laboratory studies to cause apoptosis (programmed cell death) of breast cancer cells. 

To be affected by Persin, birds would need to ingest the leaves and bark of an avocado tree or the skin and pit of an avocado. 

The avocado pulp has little Persin content, and wild birds would need to ingest a good amount of pulp to be affected.

I would not feed avocado to backyard birds, mostly because it is costly; however, if small pieces of avocado pulp make their way to kitchen scraps, I usually feed it to birds. I would not hesitate to let them have some avocado. 

Guacamole is not recommended as it has flavoring condiments and salt.

Related: A Guide to backyard bird Food & Feeder Preferences

4. Animal Fat

Animal fat is the opposite. It is considered a bad food for pet birds but is an excellent food for many wild birds. 

Bird pet owners indicate that consumption of high-fat foods, such as butter, oil, fatty meats, and nuts, can result in a build-up of cholesterol deposits in the walls of bird’s arteries (known as atherosclerosis),

predisposing them to heart disease and stroke.

Excessive ingestion of fat also can lead to obesity and all the health problems that accompany this condition. 

Some wild backyard visitors love fat.  Woodpeckers, nuthatches, chickadees, blue jays, brown creepers, wrens, kinglets, and even cardinals are fed fat regularly and can easily digest and metabolize it. 

Animal fat is offered to wild birds in suet blocks or balls. Animal fat is a high-energy food, especially needed during cold weather. 

Unlike the detrimental effects on pet birds, animal fat is beneficial for backyard birds.

5. Caffeine

Coffee is considered a dangerous food item for birds. But it refers to pet birds, not wild birds. 

Pet birds are more likely to consume caffeine-containing beverages left unattended. Wild birds do not go around looking for unattended coffee cups or drinks to have some of the content.

Caffeine stimulates the central nervous system of humans. In birds, caffeine has a similar effect and can cause arrhythmias, hyperactivity, and even cardiac arrest. 

I find it unlikely that someone would feed caffeine-containing beverages to backyard birds. 

Pet bird owners may be tempted to share some caffeinated drinks with their birds. Birds should never have caffeine as even a zip can cause problems to birds.

6. Chocolate

Like caffeine, it is evident that chocolate is an unsafe food for pet birds, which are more likely to access it or be fed by their owners. The probability that wild birds have access to chocolate is slim. 

Chocolate contains theobromine and caffeine, which stimulates the heart, increases heart rate, causes hyperactivity, induces seizures, and may even cause death in birds.

Pet bird owners are more likely to provide their pets with chocolate. 

Most backyard birds are unlikely even to try chocolate. However, birds that eat a wide variety of food such as crows, blue jays, grackles, and pigeons are likely to try it if offered to them. 

Chocolate can be toxic to birds, even in very small amounts.  Opt to offer birds fruit instead.

7. Salt

Salt consumption can raise blood pressure, renal failure, fluid retention, stroke, obesity, and osteoporosis in humans.

These effects of salt  might seem like a reason not to consume salt, but salt actually plays an essential role in the human body, and birds.

As for humans, too much salt is harmful to birds.

A bird’s excessive salt intake can result in excessive thirst, dehydration, kidney failure, and death.

How can wild birds ingest too much salt? Salted peanuts, crackers, salty chips, popcorn, pretzels, and other similar foods contain much salt. If birds overeat these foods, they can develop the problems associated with excessive salt consumption.

Food types widely accepted as unsafe for backyard birds

8. Old and Moldy birdseed and peanuts

Birdseed and peanuts are popular foods for backyard birds. But when they are stored wrongly or left wet in the feeder, they can develop mold that produces a potentially fatal toxin called aflatoxin. 

Inspect your feeders after rainy weather to see if water has infiltrated the feeder. Also, store your bird food in a dry, cool environment to maintain it in fresh conditions.

9. Moldy bread and other kitchen scraps

Molds of all types are toxic to birds. Bread molds contain many types of fungi. The dark spots or patches on the bread are a spore colonies; that is how mold reproduces. By inhaling these spores, birds, and humans, can develop an infectious lung disease called Aspergillosis. 

Even if the moldy patches are removed, birds could still get sick from it.

Though you can’t see the patches after removing them, it is still in the bread because mold has roots that penetrate the bread.

It is better to discard moldy bread and other foods altogether.

10. Bad nectar

If you feed hummingbirds and orioles, make sure you keep your nectar in prime conditions. Fresh nectar is excellent for hungry birds and will flow freely through feeders so birds can drink it easily.

Although nectar drinking birds are good at detecting good and bad nectar, they could still be harmed by bad or rancid nectar.

Rancid nectar can thicken and crystallize, coating the birds’ bills and feathers. Rancid nectar can clog feeding ports.

Discard nectar as soon as you notice a sign of benign old and rancid.

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