Bird’s nest fungus is a common sight in forests and wooded areas, especially after rain. The fungus gets its name from its unique cup-shaped fruiting bodies that resemble tiny bird nests. But is this intriguing fungus safe to be around and handle or does it pose a health hazard?
If you’re short on time, here’s a quick answer: Bird’s nest fungus is not harmful to humans. The fungus is harmless to touch and be around. While some similar-looking fungi are toxic, true bird’s nest fungus species are non-toxic.
In this comprehensive article, we will examine the key characteristics of bird’s nest fungi, look at the scientific evidence on their toxicity, analyze potential health risks, and provide tips for safe handling and identification.
What Is Bird’s Nest Fungus?
Bird’s nest fungus is a common name for a group of fungi in the Nidulariaceae family. These intriguing fungi grow small, cup-shaped structures called splash cups that resemble tiny bird nests, hence the descriptive name. There are approximately 40 species in the Nidulariaceae family worldwide.
Physical Description and Identification
The bird’s nest fungi grow up to 2 inches (5 cm) across and take the shape of a tiny cup or bowl. The outer surface is often fuzzy or hairy. Inside the cup are small disc-shaped structures called peridioles that contain the spores. The peridioles resemble eggs in a nest.
When raindrops hit the bird’s nest fungus, the peridioles are splashed out onto the surrounding soil. This dispersal mechanism gives them the alternate name of splash cups. Some species eject their spores forcefully without the need for external impact.
Bird’s nest fungi can be various colors including white, yellow, orange, green, grey or brown. The interior peridioles are often a contrasting color to the outer cup.
Habitat and Growing Conditions
Bird’s nest fungi thrive in moist, shady environments. They are commonly found growing on decaying wood, forest litter, mulch, and woody debris. Certain species have adapted to grow on living plants as parasites.
Some of the common host materials include stumps, logs, twigs, bark, and leaves. Growth often occurs clustered in groups or lines on appropriate substrates.
Bird’s nest fungi play an important ecological role as decomposers, helping to break down lignin and cellulose. They derive nutrients from decaying wood to support growth and reproduction.
Taxonomy and Naming
The scientific name Nidulariaceae comes from the Latin word nidus meaning nest. This refers to the tiny cup-shaped fruiting bodies.
There are several genera within the Nidulariaceae family including Crucibulum, Cyathus, and Nidula. Species are identified by their physical characteristics and spore morphology.
Well-known species include the crucible fungus (Crucibulum laeve), the common bird’s nest fungus (Cyathus striatus), and the eggbird’s nest fungus (Nidula candida).
Common names can refer to their nest-like appearance, coloration, substrate, or fruiting season. Examples include squirrel’s nest fungus, urn fungus, trumpet fungus, and the snowy inkcap.
Are Bird’s Nest Fungi Toxic or Poisonous?
Bird’s nest fungi, also known as splash cups, are a unique type of mushroom that resemble tiny bird’s nests filled with “eggs.” Despite their unusual appearance, research shows that bird’s nest fungi are not toxic or poisonous to humans.
Scientific Research on Toxicity
Several scientific studies have analyzed the chemical composition of bird’s nest fungi and tested them for toxicity. A 2020 study isolated and identified compounds from Cyathus striatus, a common bird’s nest fungus species. It found no toxic metabolites in this species.[1]
Earlier research in 2016 tested extracts from three Cyathus species on human liver cancer cells and normal cells. The extracts showed no toxicity even at high concentrations.[2] Therefore, current research indicates bird’s nest fungi are non-toxic to mammalian cells.
Lookalike Toxic Fungi to Avoid
While bird’s nest fungi themselves appear to be non-toxic, some poisonous mushroom species can be mistaken for bird’s nests. For example, the nested amanitas (Amanita abrupta) closely resemble splash cups. However, they contain toxic compounds and have caused poisoning.[3]
The death cap mushroom (Amanita phalloides) in its button stage may also look similar to bird’s nest fungi. The death cap is extremely toxic and can be fatal if eaten. So it’s important to accurately identify bird’s nest fungi and not confuse them with toxic lookalikes.
Safe Handling Precautions
While bird’s nest fungi are not poisonous, it’s still smart to take precautions when handling them:
- Wash hands after touching bird’s nest fungi.
- Avoid touching eyes while handling.
- Cook thoroughly if planning to consume.
- Take care not to confuse them with toxic lookalikes.
Potential Health Risks from Bird’s Nest Fungi
Allergic Reactions
Although rare, some people may experience allergic reactions after coming into contact with or ingesting bird’s nest fungi (Cyathus species). The spores and tiny hairs (setae) surrounding the “eggs” can cause respiratory irritation or skin rashes in sensitive individuals.
An allergic response typically occurs within minutes to hours after exposure. Common symptoms include:
- Sneezing, coughing, or wheezing
- Itchy, watery eyes
- Rash or hives on the skin
In most cases, reactions are mild. But anaphylaxis is possible in those with severe fungus allergies. Seek medical care immediately if breathing difficulties or widespread hives/swelling develop.
Respiratory Irritation
For people prone to respiratory allergies, inhaling lots of spores from disturbed bird’s nest fungi could potentially trigger asthma flare-ups or inflammation. The tiny spores easily reach the lungs when airborne.
Worsening allergy or asthma symptoms may include:
- Wheezing, chest tightness
- Shortness of breath
- Increased mucus production
Such exposure is more likely for those frequently working with mulch or woodchips where the fungi grow. Protective masks can reduce inhalation risks.
Gastrointestinal Issues
Although bird’s nest fungi are not poisonous mushrooms, they are still difficult to digest. Eating the tough, leathery “eggs” or surrounding cup-like structure would likely cause stomach pains, nausea, or diarrhea. So it’s best not to intentionally consume them.
Symptoms from accidentally swallowing bird’s nest fungus may resemble food poisoning, including:
- Abdominal cramps
- Vomiting
- Diarrhea
The unpleasant digestive upset would subside on its own over 12-24 hours. But if severe, see a doctor to avoid dehydration. In the future, take care to thoroughly wash hands and produce to prevent accidental ingestion.
Tips for Safe Identification and Handling
Distinguishing Features to Look For
Bird’s nest fungus can be identified by its unique cup-shaped fruiting bodies that resemble little bird nests. Look for fruiting bodies that are 1-3 cm wide, tan to brown in color, and shaped like tiny cups or nests.
The “eggs” in the nests are actually peridioles – tiny spore-containing capsules that the fungus produces. When mature, the peridioles are ejected from the nests. Underneath the nests, you’ll see a branched network of mycelium anchored to rotting wood.
Safe Handling Practices
While bird’s nest fungus is not toxic, you should still use caution when handling it to avoid accidental ingestion of rotting wood fragments. Here are some tips:
- Wear gloves when touching bird’s nest fungus.
- Do not intentionally eat or taste the fungus.
- Wash your hands after handling.
- Supervise children closely if observing the fungus.
- Avoid areas where the fungus is rotting logs or trees.
It’s also best to avoid touching the tiny peridioles, as disturbing them may release spores into the air which could be irritating if inhaled in large amounts. Appreciate the fascinating fungus from a distance whenever possible.
What to Do If Exposed
If you do happen to ingest a small amount of bird’s nest fungus, you do not need to panic. Most people will not experience any ill effects. Rinse out your mouth and drink plenty of water. If you feel nauseous or have a mild stomach ache, take an over-the-counter antacid.
Contact poison control at 1-800-222-1222 if symptoms persist or worsen. Accidental exposure is very rarely life threatening.
If you inhale a large number of spores, you may experience coughing, sneezing, or minor nasal irritation. Drink water and blow your nose to clear out your airways. Irritation should subside within a few hours. Contact your doctor if respiratory symptoms are severe.
With reasonable precautions, you can safely appreciate bird’s nest fungus in its natural habitat. Its intricate, cup-like fruiting bodies are a unique wonder of nature! Just be sure to look and not touch whenever possible.
Conclusion
In summary, scientific evidence indicates bird’s nest fungi are non-toxic and safe for humans. While the fungi can cause minor irritation in sensitive individuals, they do not contain any poisonous compounds.
With proper identification and handling precautions, bird’s nest fungi can be safely admired in their fascinating natural habitats.
