A hummingbird lives closer to the edge than almost any animal on Earth. Its heart can race to well over a thousand beats a minute, it burns energy so fast that it must feed almost constantly through the day, and it survives cold nights only by dropping into torpor, a deep dormancy that slows its body to a flicker. That extreme physiology is the source of both its brilliance and its fragility. For a hummingbird, health is really a question of energy balance, and anything that interrupts feeding, whether a disease, an injury, or a night without fuel, can become fatal within hours rather than days.
This article covers how to recognize a hummingbird in trouble, the diseases that most often affect them, and exactly what to do if you find one sick or injured. For how to prevent these problems in the first place through clean feeders, safe nectar, and a bird-friendly yard, see our guide to the threats hummingbirds face and how to help.
Why Hummingbird Health Is a Knife-Edge
To understand why a sick hummingbird declines so quickly, it helps to appreciate the machine you are dealing with. An active hummingbird’s heart rate can reach roughly 1,200 beats per minute, and it may visit hundreds of flowers a day, consuming close to its own body weight, sometimes more, in nectar. At night, or when food runs short, it can slow its heart to as few as 50 beats per minute and let its body temperature fall dramatically to conserve fuel. This is torpor, a normal and vital survival tool, not a sign of illness.
The consequence is that a hummingbird has almost no reserve. A healthy songbird can ride out a bad day. A hummingbird that cannot feed for even a short stretch, because its mouth is infected or a wing is injured, slides toward starvation fast. This is why speed matters so much when one is in trouble, and why prevention matters even more.
How to Tell a Hummingbird Is Sick
Sick hummingbirds tend to show non-specific signs: sitting fluffed up and lethargic, staying at a feeder for long periods without actually drinking, reluctance or inability to fly, or labored breathing. The single most recognizable warning sign is a swollen tongue protruding from the bill, usually the mark of the fungal infection described below.
One crucial caveat before you intervene. A hummingbird sitting motionless, especially on a cold morning or at dusk, may simply be in torpor and perfectly healthy. A bird rousing from torpor can look stunned or near death and still recover completely on its own. Because of this, watch a still bird from a distance for 20 to 30 minutes before assuming anything is wrong. Our article on torpor and winter survival explains this dormant state in detail. Genuine illness usually comes with additional signs, and true injury is usually obvious.
The Diseases That Affect Hummingbirds
Most infectious disease in hummingbirds traces back to a single source: a contaminated feeder. Warm sugar water is an ideal breeding ground for fungi and bacteria, and a shared feeder becomes a transmission point where one sick bird can infect many.
This is not a rare worst case. A California hummingbird rehabilitation programme reports that ten percent or more of the birds it admits arrive with fungal infections traced directly to unclean feeders. It is a routine reason birds come through the door.
Candidiasis (“hummingbird tongue”). This is the classic and most talked-about hummingbird disease. A Candida yeast infects the mouth and tongue, and in severe cases the tongue swells until the bird can no longer retract it or feed. Affected birds are often seen perched at a feeder with the tongue hanging out, unable to drink, and they slowly starve. Clinically the infection is a stomatitis, meaning it affects the whole mouth rather than the tongue alone, so the growths and crusting may be most visible along the jawline and inside the bill. The US Geological Survey’s National Wildlife Health Center, which has documented the condition in a Broad-tailed Hummingbird, attributes yeast stomatitis in hummingbirds to contaminated sugar-water feeders or to nectar made with honey rather than granulated sugar. Young birds appear more susceptible. It is treatable, but only by a licensed rehabilitator or avian veterinarian using antifungal medication. There is nothing a homeowner can safely do beyond getting the bird to a professional and taking the feeder down.
Aspergillosis. Another fungal infection, caused by Aspergillus mold that thrives on dirty, damp feeders. Its airborne spores are inhaled and attack the respiratory and digestive tracts, producing weight loss, nasal discharge, and a slow decline. Like candidiasis, it is a consequence of poor feeder hygiene.
Avian pox. A viral infection that produces wart-like growths, most visibly on the bill, feet, and around the eyes, and sometimes as lesions inside the mouth and throat that interfere with feeding and breathing. It spreads through direct contact at feeders and perches and by biting insects such as mosquitoes. Many birds recover from milder cases over one to two weeks, but severe infections can be fatal in a bird with so little metabolic margin. Avian pox is not transmissible to humans.
Trichomoniasis. Caused by a protozoan parasite spread at feeders and shared water, it produces cheese-like white lesions in the mouth and throat that physically block feeding and breathing, and untreated it is often fatal. It is far better documented in doves, pigeons and finches than in hummingbirds, so treat it as a possibility to be aware of rather than a common hummingbird diagnosis.
External parasites. Hummingbirds also carry mites, including nasal and feather mites. These are usually less dangerous than the infections above, though heavy infestations can weaken a bird.
The common thread is unmistakable: keep feeders clean and nectar fresh, and most of these diseases never get a foothold. Two design choices help as well. A feeder that comes completely apart can actually be cleaned, and several small feeders spaced apart beat one large one, because spacing reduces both crowding and the territorial fighting that packs birds together. The full protocol for nectar and feeder hygiene lives on our nectar recipe and feeder guide.
Injuries and Emergencies
Not every hummingbird in trouble is sick. Several kinds of accident are common, and each calls for a slightly different response.
Window collisions. A bird that strikes glass is often only stunned or concussed. Placed somewhere safe, warm, and quiet to recover, it may well fly off within an hour. If it cannot, it needs a rehabilitator. Marking your windows and repositioning feeders prevents most strikes in the first place.
Cat and dog attacks. This is the emergency people most often underestimate. A hummingbird caught by a cat or dog must be taken to a wildlife rehabilitator even if it appears completely unharmed. Cat and dog saliva carries bacteria that are deadly to birds, and these enter through punctures so small that the bird’s skin closes over them within minutes, hiding the wound. There may also be crushing injuries you cannot see. Without prompt antibiotic treatment, a bird that looks fine can die of infection days later. If your pet catches a hummingbird, treat it as urgent regardless of how the bird looks. Keeping cats indoors prevents this entirely.
Trapped indoors. Hummingbirds that get into a garage, greenhouse, or house instinctively fly upward and can exhaust themselves against the ceiling, so a trapped bird needs help before it collapses. Dim the lights, open every door and window wide, and try to lure the bird lower with a feeder or a bright flower held near an exit.
Tangled in a spider web. A hummingbird caught in a large web may be dehydrated, in shock, or injured by the time it is found, and freeing it safely takes care.
The step-by-step handling for each of these is in our guide on what to do if you find an injured hummingbird.
What to Do If You Find a Sick or Injured Hummingbird
If you find a hummingbird that genuinely needs help, the essentials are quick to state. First, make sure it actually needs rescuing rather than simply rousing from torpor, watching a still bird for 20 to 30 minutes before you act. If it clearly needs help, contain it gently in a warm, dark, ventilated box lined with smooth cloth, never terrycloth, whose loops can snare a hummingbird’s claws. Then contact a licensed wildlife rehabilitator right away.
Speed is everything, and it is illegal to keep a hummingbird yourself, even briefly, under the Migratory Bird Treaty Act.
If a rehabilitator cannot be reached quickly and the bird is fading, a few drops of fresh nectar made from one part white sugar to four parts water can buy time. Never use honey, never add dye, and never force the bill open. Nectar alone cannot rehabilitate a bird; it only buys hours.
Because getting those first steps right can decide whether the bird lives, the full procedure is covered separately, including safe handling, freeing a bird from a spider web, helping one trapped indoors, and finding a rehabilitator near you. See what to do if you find an injured hummingbird.
The Rehabilitation Reality
Even in expert hands, hummingbirds are hard to save. Licensed rehabilitators provide precisely calibrated feeding, careful warmth and stress management, medication where a disease is treatable, and judgment about when a bird is ready to be released. It is skilled, demanding work, and not every bird makes it. Getting an injured hummingbird into that expert care quickly is the best chance you can give it, and it is the most valuable thing an ordinary person can do.
When a bird recovers from a simple stun or a spell trapped indoors, release is straightforward: take the open box outside near flowering plants, step back, and a healthy bird will usually be gone within a minute or two. If it will not or cannot go, it still needs help.
Prevention Is the Real Medicine
Almost every disease mentioned in this article is preventable with clean feeders and safe nectar, and most injuries are preventable with indoor cats and bird-safe windows. Because those are all yard and household practices rather than medical ones, they are gathered with the rest of the how-to-help guidance on our threats to hummingbirds article. Planting a garden that feeds them naturally helps too, since a yard with flowers and insects puts less pressure on any single feeder.
The kindest thing you can do for a hummingbird’s health is to make sure it never needs rescuing.
Frequently Asked Questions
How can I tell if a hummingbird is sick or just resting?
A resting or torpid hummingbird can look alarmingly still and recover on its own, so watch from a distance for 20 to 30 minutes first. Genuine illness usually brings extra signs such as a swollen tongue, labored breathing, or an inability to fly even after warming up.
What is the swollen tongue I sometimes see on a hummingbird?
That is usually candidiasis, a yeast infection of the mouth from a dirty or fermented feeder that swells the tongue until the bird cannot feed. It needs a licensed rehabilitator, and it is preventable with regular feeder cleaning.
My cat caught a hummingbird but it looks fine. What should I do?
Treat it as an emergency and get it to a wildlife rehabilitator anyway. Cat saliva carries bacteria that kill birds through tiny punctures you cannot see, and untreated birds often die of infection days later.
Can I keep and raise an injured hummingbird myself?
No. It is illegal under the Migratory Bird Treaty Act, and hummingbirds are extremely difficult to care for. Contact a licensed rehabilitator instead.
Are hummingbird diseases dangerous to people?
The common ones, such as avian pox, are not transmissible to humans. The greater risk is to other hummingbirds through a shared, unclean feeder.
How common are feeder-borne infections really?
More common than most people assume. One California rehabilitation programme reports that ten percent or more of the hummingbirds it receives arrive with fungal infections traced directly to dirty feeders.
Should I take my feeder down if I see a sick bird?
Yes. Take it down, clean it thoroughly, and leave it down for a couple of weeks so birds disperse rather than continuing to share a contaminated surface.
Conclusion
A hummingbird’s health rests on a razor’s edge of energy, which is exactly why understanding it matters. Knowing how to spot a bird in genuine trouble, resisting the urge to rescue one that is only resting, and getting a truly sick or injured bird into expert hands quickly are the ways an ordinary person makes a real difference. And the surest help of all happens before anything goes wrong, in a clean feeder and a safe yard.
Quiz: Sick and Injured Hummingbirds: What to Know
The quiz questions are grounded in veterinary, rehabilitation, and ornithological sources. Key references are listed below:
A federal wildlife-health case report with histopathology from a Broad-tailed Hummingbird in Arizona, showing yeast organisms invading the tongue and mouth epithelium. Notes that yeast stomatitis in hummingbirds is widely attributed to contaminated sugar-water feeders or nectar made with honey rather than granulated sugar, and that young birds may be more susceptible.
Clinical veterinary reference on Candida and Aspergillus infections in birds, including the role of poor husbandry and unclean environments in triggering candidiasis.
Veterinary account of avian pox: how the virus enters through breaks in skin or mucous membranes, spreads by direct contact, contaminated feeders and perches, and biting mosquitoes, and why removing and disinfecting feeders helps control an outbreak.
Documents the dry and wet forms of avian pox in hummingbirds specifically, and explains why their high metabolic requirements make them especially vulnerable to the virus.
Authoritative rescue guidance, including the illegality of possessing a hummingbird under the Migratory Bird Treaty Act, the use of a ventilated container, and the urgency created by a hummingbird’s high metabolism.
Field-research guidance on safe containment, using a dark ventilated box lined with smooth cloth rather than terrycloth, and locating a licensed wildlife rehabilitator.
Audubon’s feeder guidance, including cleaning frequency by temperature and the reasons for avoiding honey and other sweeteners, which is the prevention side of the diseases covered here.