Search of the Week: “if refined sugar is so bad for us, then why do we feed it to hummingbirds??”

3 Rufous, 1 Costa'sBecause hummingbirds aren’t humans, as I’ve pointed out here before, and one species’ meat is another species’ poison.

We modern humans are large, sedentary primates whose evolution hasn’t prepared us for our current unnatural abundance of calorie-dense foods, including sugars. We eat vastly more sugars than our ancestors did, and we pay the price in obesity, insulin resistance, type 2 diabetes, and other problems. *

Hummingbirds, on the other hand, are tiny, hyperactive creatures with raging metabolisms fueled in large part by naturally concentrated sugar sources (primarily flower nectar). Our smaller northern species need at minimum the caloric equivalent of ~40% of their body weight in sugar every day just to function. Even at our elevated consumption levels, it would take the average American more than six months to eat 40% of his or her body weight in sugar.

All plants manufacture sugars in their tissues, and many use them to bribe animals for pollination services. Sucrose, a naturally occurring sugar that most of us know as white table sugar, is the main sugar found in the nectars of hummingbird-pollinated flowers and so is the most natural ingredient to put in hummingbird feeders. We get our sucrose from the sap of sugar cane and sugar beets, but it’s chemically identical to the sucrose in flower nectar. (Refining sugar isn’t like refining oil; it involves filtering the plant juices to remove contaminants, including some that are dangerous to hummingbirds, and crystallizing the purified sugars.) 

* I’ve also said here before that sugar doesn’t cause diabetes, based on assurances by ostensibly credible organizations, but recent research has established a very strong correlation between sugar availability and type 2 diabetes. It appears that Big Sugar took a page from Big Tobacco’s playbook and worked tirelessly for decades to keep the public from learning the facts about their product.

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Search of the Week: “why don’t hummingbirds get diabetes?”

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Beet juice in hummingbird feeders? NO!

Vampire hummingbird expert + urban myth remix

It doesn’t

Just a quick response to whoever is searching for information on whether the sugar water in feeders causes diabetes in hummingbirds. Sugar doesn’t cause diabetes in people, either, but most of us eat way more of it than big sluggish mammals should. This contributes to obesity, which is a significant risk factor for developing type 2 diabetes.

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Search of the Week: Why don’t hummingbirds get diabetes?

Vampire hummingbird expert + urban myth remix

This has to be the weirdest place to get hummingbird information ever. Thursday night the SciFi Channel ran a B-minus horror flick called The Insatiable. Nebbishy guy holds a sluttily clad female vampire captive in a steel cage in his basement. As he and the bloodsucker chat, the talk turns to…hummingbirds. Seems he was entranced by the hummingbirds in his yard and put out a feeder for them, but they all disappeared. She says (and I’m paraphrasing only slightly), “Of course they disappeared. You gave them honey water*. It ferments into alcohol. Their systems are too delicate to handle it. But they couldn’t resist it. So they drank it until they died. If you go look under that feeder, you’ll find a pile of dead hummingbirds.”

This is one of those times when I wish I was podcasting, because sputters and choking noises are so much more expressive than mere words. I’m still trying to figure out what the scriptwriters intended that little exchange to reveal about the characters, not to mention why they thought an exclusively nocturnal creature would know or care anything about exclusively diurnal birds. What’s weird is that this was my third encounter in three days with the “alcohol kills hummingbirds” rumor.

Thursday morning a participant in a tour sponsored by Birds & Blooms Magazine asked me if I was familiar with Jack Aprill, the self-styled hummingbird guru of Leaming’s Run Gardens in New Jersey. I am, mainly because I was asked to help my friends and colleagues at the Cape May Bird Observatory deal with fallout from Aprill’s strident advocacy against feeding hummingbirds.

Aprill’s condemnation of hummingbird feeders is based on the unsupported ideas that a) sugar water in feeders rapidly ferments into alcohol, which b) is a deadly poison to the birds. Before his retirement, he reportedly preached the evils of hummingbird feeders on his guided tours of the gardens, and his self-published book with the same message is still available.

As it happens, I had reacquainted myself with Jack Aprill on Wednesday morning while drafting a response to a reporter who had been told that hummingbirds get cirrhosis of the liver from drinking fermented sugar water from neglected feeders, and that the mortgage crisis was escalating the problem because feeders were being left behind at foreclosed homes.

Are we witnessing the birth of a new urban myth? This is my first encounter with this one, and it doesn’t even seem to have hit the Internet yet (oops, I guess it has now). It sounds like a creative remix of Aprill’s alcohol ideas and the persistent myth that hummingbirds get diabetes because we feed them white sugar, though I’m unclear on whether cirrhosis figures in Aprill’s version. (If you ever took one of Jack’s garden tours or own his book, please leave a comment with details.)

The diabetes myth is easy to bust. White sugar, a.k.a. sucrose, is the main sugar found in the nectar of hummingbird pollinated flowers and not a direct cause of diabetes even in humans. Too bad the alcohol issue isn’t quite so straightforward. Home brewers and wine makers understand deliberate fermentation inside and out, but there seems to be little research relevant to fermentation rates “in the wild” and none whatsoever on the effects of ethanol consumption on hummingbirds. I’d just as soon stay in the dark on that second point than imagine some biology student or Ph.D. force-feeding alcohol to hummingbirds, but documenting the rates at which hummingbird feeder solutions ferment sounds like an excellent science fair project (hint, hint).

From my own research on free-living hummingbirds, I’m highly skeptical that alcohol presents a health hazard. Most banding studies, mine included, are based around feeders, and patterns of longevity in these studies provide insights into their impact. Feeder-using banded hummingbirds are living to ripe old ages, far longer than we would have guessed possible for such a small creature, which suggests that if small amounts of ethanol are killing them, it’s doing so very…very…sloooowly.

This makes sense from an evolutionary perspective. Any sufficiently dilute solution of sugar(s) and water, including nectar, tree sap, and the juices of overripe fruits, has the potential to ferment. If a sugar solution sits around long enough in the open air, wild yeasts will colonize it, consuming the sugars and excreting ethanol (“grain alcohol,” the drinkable kind) as a waste product. Any creature that can’t tolerate small amounts of ethanol, whether over short- or long-term exposure, would be poorly adapted to a diet of fermentation-prone nectar and should have been weeded out by natural selection long before hummingbird feeders came on the scene. In fact, as is the case for the primitive beers brewed by our ancestors, the yeasts may give natural nectar a nutritional boost, and the alcohol they excrete may discourage the growth of pathogenic microbes.

So, we can safely assume that hummingbirds must be able to tolerate some alcohol, but we still have no evidence for how much alcohol it might take to kill a hummingbird outright or lead to fatal liver disease, or even whether they get drunk. (Bees do, but at least one nectar-drinking mammal holds its liquor really well.) This is one place we commonly go astray in relating to the natural world: expecting what we know (or think we know) about ourselves to apply equally to species that evolved with vastly different opportunities and challenges. That’s the origin of the myth that white sugar is bad for hummingbirds. It certainly is unhealthy for big, sluggish mammals like ourselves in the unnatural quantities we consume these days, but in any quantity it’s a perfectly natural, even essential fuel for tiny hyperactive birds. I’m not saying that alcohol is an essential nutrient for hummingbirds, but I wouldn’t be surprised to learn that they have a much higher tolerance for the stuff than we humans, who have only had regular access to large quantities of it for a few thousand years (since we learned how to brew beer and wine).

If we err on the side of caution and assume that large quantities of alcohol aren’t good for hummingbirds, the next logical question is: Do the unnatural aspects of fermenting feeders, high volume in particular, make them unnaturally dangerous? A neglected feeder that still has solution in it after a couple of weeks might have a higher level of alcohol than almost any natural source, but would it still be palatable to the birds? In Mexico, where feeders are relatively rare, I’ve seen drought-stressed hummingbirds drinking really nasty-looking sugar water from mold-encrusted feeders that may have never been properly cleaned. This debunks the wishful thinking that hummingbirds will starve rather than drink spoiled feeder solution, but this was an extreme situation. Any flowers or fresher feeders nearby should have a competitive advantage over the fermenting feeder as the yeasts use up its sugar. It’s hard to imagine a situation in which hummingbirds would be drinking fermented sugar water consistently for months or years, the kind of chronic exposure it takes for humans to develop cirrhosis. (Unless, of course, the vampire was right and they find alcohol irresistable.)

I’m an open-minded skeptic, so if anyone has any evidence to support (or debunk) the cirrhosis claim, please contact me (especially staff and volunteers at wildlife rehabilitation centers, who would be the only people in a position to document liver disease in wild hummingbirds). In the meantime, keep up the regular feeder maintenance and support organizations that work against documented, serious threats to hummingbirds and other wildlife, such as habitat destruction, climate change, pesticides, invasive species, free-roaming cats, collisions with windows, communications towers, and other man-made obstacles, and possibly even red dyes. And don’t forget the thousands of people and pets left homeless by the mortgage crisis—they’re in dire need of our concern and advocacy.

*Addendum: The vampire hummingbird expert specified honey water, and non-fictional hummingbird experts often warn against it, too, though mainly because honey has been reported to cause a fungus-like disease of the throat and tongue (presumably candidiasis). This is almost an urban myth itself, as no one seems to have any hard evidence linking the two, but there are other good reasons to avoid using honey in hummingbird feeders. The vampire was correct that honey ferments rapidly when diluted to feeder strength, in part because its main sugars, glucose and fructose, are readily used by yeasts. These simple sugars predominate in the nectars of insect-pollinated flowers, while sucrose, a disaccharide, predominates in bird-pollinated flowers and is preferred by hummingbirds. Even if honey contained the “right” sugars to feed hummingbirds, it’s extremely expensive. So for happy, healthy birds, cleaner feeders, and a bigger bank balance, stick with plain white sugar.

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Search of the Week: “why don’t hummingbirds get diabetes”

Feeder Solution Evolution Part I: The basics

Search of the Week: “can hummingbirds get fat”