Is foxglove toxic to hummingbirds?

Quick Answer

Yes, foxglove is toxic to hummingbirds. All parts of the foxglove plant, including the leaves, flowers, and seeds, contain cardiac glycosides that can cause heart problems if ingested by hummingbirds. Hummingbirds have very fast metabolisms and small bodies, making them more susceptible to the toxins in foxglove than other animals. Even small amounts of foxglove can be fatal to hummingbirds. It’s best to avoid planting foxglove in gardens that attract hummingbirds.

What is foxglove?

Foxglove, also known as Digitalis purpurea, is a common perennial plant that is toxic to both humans and animals. Foxglove is native to Europe but has been introduced to other parts of the world. The plant produces tall stalks topped with tubular flowers in shades of purple, pink, yellow, and white.

All parts of the foxglove plant contain cardiac glycosides, which are chemicals that affect heart function. The toxins produced by foxglove can cause vomiting, diarrhea, weakness, confusion, heart problems, seizures, and even death if enough is ingested.

Key facts about foxglove:

• Foxglove is a flowering plant in the Plantaginaceae family.
• It is native to Europe, southwestern Asia, and northwestern Africa.
• The plant can grow up to 5-6 feet tall.
• Flowers bloom in late spring and summer.
• Colors include purple, pink, white, and yellow.
• All parts are poisonous, especially the leaves and seeds.
• Contains cardiac glycosides that affect heart rate and rhythm.

Foxglove has been used medicinally for centuries to treat heart conditions like congestive heart failure and arrhythmia when used carefully under medical supervision. However, ingesting the plant can be very dangerous and life-threatening without oversight.

Are hummingbirds attracted to foxglove?

Yes, hummingbirds are attracted to foxglove flowers. Hummingbirds have very fast metabolisms and are drawn to tubular flowers that provide nectar. The colorful, tubular-shaped flowers of foxglove are appealing to hummingbirds looking for food sources.

Hummingbirds like foxglove flowers because:

• Bright colors attract hummingbirds
• Tubular shape is perfect for hummingbird beaks
• Flowers produce nectar that hummingbirds drink
• Blooms throughout hummingbird season
• Tall stalks make flowers easy to access

Foxglove starts blooming in late spring or early summer, which coincides with when hummingbirds migrate back to northern climates. The flowers continue blooming into mid-summer, providing a constant food source for visiting hummingbirds.

Gardeners will often see hummingbirds delicately feeding on foxglove flowers. However, this interaction can be dangerous if the hummingbirds ingest the toxic parts of the plant.

Why is foxglove toxic to hummingbirds?

Foxglove is toxic to hummingbirds because it contains cardiac glycosides, which can cause heart problems if ingested. Here are a few key reasons why foxgloves pose a danger:

• Cardiac glycosides interfere with electrolyte balance
• Causes heart arrhythmias and irregular heartbeat
• Can cause the heart to stop beating
• Hummingbirds have very fast heartrates
• Small body size makes poisoning more likely
• Fast metabolism processes toxins quickly

The fast metabolic rate of hummingbirds unfortunately allows the toxins from foxglove to take effect very rapidly. Their small size also means it takes only a very small amount of foxglove to reach toxic levels in their bodies.

Even trace amounts of the cardiac glycosides found in foxglove pollen, nectar, or sap can be enough to paralyze the heart of a tiny hummingbird. Death can occur within hours of ingestion.

How foxglove affects hummingbird hearts:

• Causes electrolyte imbalance, especially potassium
• Interrupts heart’s electrical signals
• Slows and blocks electrical impulses
• Causes arrhythmias and irregular contraction
• May cause convulsions, paralysis, and death

With their extremely high metabolisms and fast heart rates, hummingbirds are sadly very vulnerable to the effects of foxglove cardiac glycosides. Even a small amount can fatally disrupt their heart rhythms.

Signs of foxglove poisoning in hummingbirds

Here are some signs that a hummingbird may have ingested toxins from foxglove:

• Vomiting
• Diarrhea
• Labored or irregular breathing
• Visible cardiac distress or arrhythmias
• Loss of appetite
• Lethargy, drooping wings
• Tremors or muscle spasms
• Disorientation, flying erratically
• Seizures
• Coma
• Death

If a hummingbird starts exhibiting any odd behaviors like weakness, spasms, or seizures, foxglove poisoning may be the cause. Vomiting and diarrhea can happen quickly after ingesting parts of the plant as the body tries to expel the toxins.

Without swift treatment, the foxglove cardiac glycosides can soon lead to paralysis, coma, and death in just hours or days. So observing any abnormal signs in hummingbirds that visit foxglove flowers indicates poisoning may have occurred.

Is there an antidote for foxglove poisoning in hummingbirds?

Unfortunately, there is no standard antidote or treatment for foxglove poisoning in hummingbirds. Some things that may help counteract the toxins include:

• Inducing vomiting if poisoning just occurred
• Administering activated charcoal to absorb toxins
• Providing electrolyte fluids to stabilize heart function
• Gently handling and keeping hummingbird warm and calm

Getting a hummingbird experiencing cardiac distress to a wildlife rehabilitation center as quickly as possible is the best chance for survival. There, supportive care such as electrolyte therapy and medications to regulate heart rhythm can be administered to try to counteract the foxglove toxins.

However, the effects of foxglove poisoning are often irreversible once the toxins reach the heart. Many times, even swift veterinary treatment cannot undo the cardiac damage once it has occurred in hummingbirds.

Prevention is truly the best cure when it comes to protecting hummingbirds from foxglove poisoning. Avoiding planting foxgloves in gardens that attract hummingbirds is recommended.

How much foxglove is deadly to hummingbirds?

It only takes a very tiny amount of foxglove to potentially be lethal to a hummingbird. Exact lethal doses are unknown, but even traces of foxglove pollen, nectar, or sap may contain enough cardiac glycosides to fatally disrupt their heart rhythms.

Some experts estimate as little as 1/10th of a gram of dried foxglove leaf material could be fatal if ingested by a hummingbird. This is only about the weight of 1-2 paper clips worth of foxglove.

Given their miniscule body size, hummingbirds do not have to ingest much foxglove at all for it to endanger their lives. It is best to assume even small amounts could be toxic.

Foxglove toxicity levels:

• Traces of pollen, nectar, or sap may be toxic
• Estimated 1/10 gram dried leaf material may be lethal
• No minimum known safe dose
• Toxins act rapidly due to fast hummingbird metabolism
• Effects often irreversible once heart damaged

Without a way to measure exactly how much foxglove nectar a hummingbird has ingested, it is impossible to know if a lethal dose has been reached. Given their tiny body size, it is safest to prevent any consumption of foxglove by hummingbirds.

Can foxglove be made safe for hummingbirds?

There is no known way to neutralize the cardiac glycosides found in foxglove to make the plant safe for hummingbirds. Here are a few key reasons why foxglove cannot be made non-toxic:

• Cardiac glycosides are inherent throughout the plant
• Cannot be neutralized or washed off
• Attempts to genetically remove glycosides also removes medicinal properties
• No effective antidote to reverse glycoside effects
• Even pollen, sap, and nectar carry risk

Because the cardiac glycosides are integrated into the basic cellular structure of foxglove, there is no current way to remove the toxins while keeping the plant alive. All parts carry risk, even just the pollen transferred by bees and hummingbirds.

Genetic modification to suppress glycoside production also eliminates the medicinal properties of foxglove that have made it valuable as a heart medication. There is no known way to neutralize the toxins while preserving the beneficial effects.

Overall, it appears keeping foxglove away from areas frequented by hummingbirds is the only foolproof method to avoid potential poisoning. No part of the plant can be made safe for hummingbird consumption.

Alternative flowers that are safe for hummingbirds

Here are some safer flower options to plant in hummingbird gardens instead of foxglove:

These flower varieties provide plentiful and safely shaped nectar sources for hummingbirds. They serve as attractive alternatives to foxglove in gardens where hummingbird safety is a priority.

Conclusion

In summary, foxglove is highly toxic to hummingbirds, even in small amounts. All parts of the foxglove plant contain cardiac glycosides that can cause life-threatening heart problems in hummingbirds. There is no way to neutralize these toxins while keeping the plant alive.

The safest approach is to avoid planting foxglove in areas frequented by hummingbirds. Instead, provide alternative flower sources like trumpet vine, cardinal flower, and petunias that will attract hummingbirds without putting them at risk. With some thoughtful plant substitutions, we can enjoy the beauty of hummingbirds visiting our gardens safely.