Hummingbirds are remarkable little birds capable of hovering in mid-air and migrating thousands of miles every year. Their survival depends on having access to adequate nutrition in the form of flower nectar and small insects. Like all living creatures, hummingbirds face threats from predators and diseases. One disease that has recently emerged as a major threat to hummingbirds is fungal infections.
What is a fungal infection?
A fungal infection occurs when invasive fungus takes hold and begins growing on or inside a living organism. Fungi are a type of microorganism that thrive in warm, moist environments. There are thousands of species of fungus in the environment and while most are harmless, certain types can cause infection when they invade animal tissue. Some common fungal infections include:
- Aspergillosis – infection caused by Aspergillus fungus
- Blastomycosis – infection caused by Blastomyces fungus
- Candidiasis – yeast infection caused by Candida fungus
- Cryptococcosis – infection caused by Cryptococcus fungus
- Histoplasmosis – infection caused by Histoplasma fungus
Fungal infections are initiated when fungal spores are inhaled or make contact with broken skin or mucous membranes. The infection then spreads as the fungus proliferates within the body. Fungal infections can affect different tissues and organs depending on the type of fungus.
Common symptoms of fungal infections
Symptoms of a fungal infection depend on where in the body the infection takes hold but can include:
- Rash or irritation on skin
- Coughing or wheezing
- Fever and chills
- Fatigue or body aches
- Swelling or inflammation
- Discharge or bleeding
- Gastrointestinal distress
If left untreated, the infection can spread through the bloodstream and respiratory system and can damage organs or be fatal. Birds with fungal infections often show non-specific symptoms like lethargy, fluffed up feathers, and loss of appetite.
Are hummingbirds susceptible to fungal infections?
Hummingbirds are at risk for developing fungal infections due to their small size, high metabolic rate, and reliance on accessing flower nectar and insects.
Factors that make hummingbirds prone to fungal disease include:
- Small body size – With an average weight of 2-6 grams, hummingbirds are extremely small birds with a high surface area to body mass ratio. This makes it easier for fungi to establish on their skin and be absorbed into the bloodstream.
- High metabolism – Hummingbirds have an incredibly fast metabolism and must consume up to half their body weight in nectar each day just to survive. The exertion required for feeding puts physiological stress on their bodies.
- Exposure at flowers – Fungi like Ascomycetes thrive on the pollen and nectar inside flowers, putting hummingbirds at risk when they access these food sources.
- Compromised immune systems – Migration and torpor take a toll on hummingbird immune function. The stress of migration combined with physiological effects of torpor can leave them immunocompromised.
- Climate threats – Hummingbirds are sensitive to small environmental changes. Increased storms, droughts, and warming linked to climate change may create favorable conditions for fungal growth.
With their extreme energetic demands, hummingbirds often operate at their physiological limit. The added burden of fighting off fungal infections can rapidly lead to debilitation and death.
What types of fungal infections affect hummingbirds?
Some fungal infections that can afflict hummingbirds include:
Aspergillosis
Caused by Aspergillus fungus, aspergillosis is considered one of the most significant fungal diseases in birds. Spores are usually inhaled and germinate in the lungs, causing respiratory illness. Aspergillosis can manifest as pneumonia, air sac infection, and disseminated infection if the fungus spreads to other organs. Symptoms include labored breathing, lethargy, weight loss, and discharge from eyes or nares.
Candidiasis
Candidiasis is caused by Candida fungal species like Candida albicans. Candida fungus is part of normal microbial flora but can proliferate and cause infection in immune-compromised birds. Candidiasis can affect the GI tract, cloaca, skin, and respiratory system. Symptoms may include poor appetite, inflamed mucous membranes, difficulty breathing and swallowing, and thick mucus discharge.
Trichomoniasis
Avian trichomoniasis is caused by the parasitic protozoan Trichomonas gallinae transmitted at bird feeders. Hummingbirds infected with trichomoniasis show white, cheese-like lesions and ulcerations in their mouth and throat that obstruct feeding and breathing. Other symptoms include lethargy, ruffled feathers, and wasting. Without treatment, trichomoniasis is often fatal within 2 weeks of exposure.
Prompt diagnosis and treatment is required for any hummingbirds exhibiting these types of infection symptoms.
Can hummingbirds survive a fungal infection?
The survival outlook for a hummingbird with a fungal infection depends on the type of fungus involved, severity of symptoms, and how quickly treatment can be provided by a wildlife rehabilitator.
Mild fungal skin infections may be survivable if the antifungal treatment is started before the infection progresses. Gastrointestinal and respiratory fungal infections have a poorer prognosis.
According to one analysis, survival rates for hummingbirds treated for aspergillosis was only 15% even with aggressive antifungal therapy. Hummingbirds are so physiologically fragile that they can deteriorate rapidly once infected.
However, early veterinary intervention can greatly improve the chances of recovering from a fungal infection. Here is a rough survival outlook for hummingbirds with fungal infections when properly treated:
Infection Type | Survival Outlook |
---|---|
Aspergillosis | 15-30% survival |
Candidiasis | 50% survival |
Trichomoniasis | 70% survival if treated early |
A hummingbird’s best chance is to get prompt veterinary therapy with antifungal and supportive care before the infection advances too far. However, fungal infections remain very dangerous for hummingbirds.
How can hummingbird fungal infections be prevented and managed?
Strategies for preventing and managing hummingbird fungal disease include:
- Keep feeders clean – Change nectar and scrub feeders at least once per week to remove fungal spore contamination.
- Avoid overcrowding – Space feeders widely apart and do not allow crowding to discourage disease transmission.
- Promptly remove sick birds – Isolate and treat any birds showing signs of illness to prevent spread to others.
- Antifungal agents – Incorporate antifungal medications into nectar to reduce fungal blooms.
- Boost immunity – Ensure ample natural food sources to support immune function and resilience.
- Public awareness – Educate the public on symptoms of fungal infections to encourage early treatment.
- Hummingbird care network – Develop dedicated wildlife rehabilitators equipped to treat hummingbird fungal diseases.
While fungal infections pose a substantial threat, proactive management and vigilance can reduce transmission and increase the chances of recovery for infected hummingbirds.
Key Points
- Common fungal infections affecting hummingbirds include aspergillosis, candidiasis, and trichomoniasis.
- Factors like small size, high metabolism, and feeding behaviors put hummingbirds at high risk of fungal infections.
- Respiratory, gastrointestinal, and skin infections have variable survival rates depending on treatment.
- Prompt diagnosis and rehabilitation care are critical for survival.
- Preventive measures like sanitation, isolation, and immunity support can help reduce outbreaks.
Conclusion
Hummingbirds face serious threats from debilitating fungal infections that can rapidly compromise their fragile health. While some types like aspergillosis and trichomoniasis have very high mortality rates even with treatment, others like candidiasis have more favorable prognoses when addressed early. Supportive care from wildlife rehabilitators offers the best chance of recovery. However, preventive measures are key to help control outbreaks and give hummingbirds the best odds against fungal disease risks as environmental conditions continue to change.