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.

Related posts:

Feeder Solution Evolution Part 1: The basics

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

Search of the Week: “is molasses ok to feed hummingbirds”

Beet juice in hummingbird feeders? NO!

Vampire hummingbird expert + urban myth remix


Bad news about free-roaming cats

Lucky Wilbury, our most recent shelter cat, lounging on the cat throne. We have no intention of allowing Lucky outdoors off leash, as much for his protection as for the wildlife. Our previous cat, Bart, snuck out the door one night when the coyotes were howling and Great Horned Owls hooting. He was never seen again. We feel like we let him down and only hope that he met a quick, merciful end, not like the weeks, months, or years of suffering endured by most stray and feral cats.

There’s been a recent flurry of bad news about free-roaming cats, which is timely considering a recent visit to the comments section of one LB&E post by an incipient cat hoarder. His last comment was so out of touch with reality that I did him a favor by declining to publish it. That’s tragically typical of the breed, but I hold a polyanna-ish confidence in the power of facts to overcome the disinformation thrown around by obsessive cat defenders (OCDs).

Oregon Plague: Woman Contracted Disease From Cat

Thought theBlack Death” was history? Think again. These days, plague is usually contracted from the bites of fleas in and around rodent colonies, but cats and dogs that eat infected rodents can contract and transmit the disease and/or bring home infected fleas to their human families. (Warning: The article is headed by a grisly photo of the original victim’s blackened hand.)

Rabies threat prompts town to trap feral cats

A kitten adopted from a TNR program tests positive for rabies:

The kitten was friendly and domesticated, according to the family that adopted it. Because of its demeanor, police aren’t sure that the kitten was part of the feral colony – there is a chance it was abandoned in the park. [emphasis mine]

One big reason that TNR is such a failure at reducing, much less eliminating, feral cat colonies is that the conspicuous presence of “managed” colonies in public places tends to attract people looking for places to dump unwanted pets. Inadequate commitment to vaccinating all cats in a colony at recommended intervals to prevent outbreaks of rabies, feline immunodeficiency virus, feline leukemia virus, etc. makes it a public health failure, too.

Study Finds Free-Roaming Cats Pose Threat from “Serious Public Health Diseases”

This press release from the American Bird Conservancy reports on an important new paper published in the journal Zoonoses and Public Health: “Zoonotic Diseases Associated with Free-Roaming Cats,” by R.W. Gerhold and D.A. Jessup (2012). The study reviewed the various diseases that infect free-roaming cats and the implications for public health of trying to manage feral cat populations via TNR. Three significant findings related to the second story above:

  • Free-roaming cats are disproportionately responsible for exposing humans to rabies.
  • Cat colonies “managed” by TNR attract unneutered, unvaccinated cats and increase their survivorship and reproductive success, leading to increases in colony size and potential for disease transmission.
  • Feeding stations for feral cats attract wildlife such as raccoons, skunks, and foxes that may transmit rabies and other diseases to the cats and/or carry feline diseases into the wild. (Wild predators that prey on free-roaming cats are also vulnerable to their diseases and parasites; strains of feline leukemia virus that have killed critically endangered Florida Panthers have been linked to domestic cats.)

An even more insidious public health menace related to free-roaming cats is toxoplasmosis. The organism that causes this disease can infect many animals, but cats are the only ones that pass the parasite’s infective oocysts in their feces. A cat may only shed oocysts for a couple of weeks early in the infection, but they can persist in contaminated soil—garden beds, children’s sand boxes—for years. Authors Gerhold and Jessup cited a 2011 study that found that 63 percent of the patients with acute toxoplasmosis had become infected through contact with cat feces.

One more cat item that relates to the “kitty-cam” study in Georgia:

Opinions from the Front Lines of Cat Colony Management Conflict

The authors conducted a survey of opinions about feral cats and their management with cat colony caretakers (CCCs) and bird conservation professionals (BCPs) across the United States. Naturally, they found strong polarization between the two groups (even though substantial portions of both described themselves as both cat- and bird-people), and they also documented how poorly informed/in denial CCCs were about the impacts of free-roaming cats on wildlife and public health. Even among the BCPs, awareness of feral cat issues was lower among respondents who lacked college degrees, so there’s a need for outreach and education even within the bird conservation community.

The authors suggest:

To the extent the beliefs held by CCCs are rooted in lack of knowledge and mistrust, rather than denial of directly observable phenomenon, the conservation community can manage these conflicts more productively by bringing CCCs into the process of defining data collection methods, defining study/management locations, and identifying common goals related to caring for animals… Our findings suggest that when such collaborative measures are not logistically possible, CCCs may be more likely to accept scientific results framed in terms of directly observable phenomenon (e.g., feral cats kill wild animals) rather than indirectly observable phenomenon (e.g., feral cats contribute to global declines among songbird populations). For instance, most CCCs see direct evidence of cats killing wild animals and would find denying those experiences difficult without creating some degree of cognitive dissonance.

In discussion of the Georgia “kitty-cam” study, OCDs glommed onto the low number of documented kills by the pets in the study, even though a conservative extrapolation of the results suggests that free-roaming cats kill more than 2 billion animals per year. It seems obvious that feral cats, even those that are being fed, will hunt more than well-fed, part-time outdoor pets, but seeing might be believing. It’s time to put “kitty-cams” on feral cats in managed colonies so that CCCs and OCDs can see the carnage up close and personal.

I get mail

I get a lot of mail this time of year asking for help with hummingbird identification. Those that are accompanied by photos are usually pretty easy to deal with, but ones like this give me a bad, bad feeling:

I live in Michigan. My daughter had a friend that lived along the Maple river. They saw yellow, red and green hummingbirds. These were brightly colored. She discribed the yellow one as looking like a goldfinch. They all appeared to be the same type of birds only different bright colors.

My sister just this week saw one that was a solid bright sky blue.

I’ve never heard of hummingbirds that have this coloring.

That’s because there aren’t any. A red and green hummingbird in Michigan is almost certainly a male Ruby-throated, but there are no yellow or solid sky blue hummingbirds among the world’s 340-odd species. None. Anywhere. However, those bright colors are found in many tiny songbirds, including warblers, buntings, and yes, finches. I shared this information, suggesting a couple of field guides and Web sites, and received this reply:

You answered my question as far as these being known.  They were definitely hummingbirds.  they were to small for anything else and the yellow, red and green variety were eating from the feeder.  my daughters friend had hit one on the yellow ones with his car and killed it.  Do you have any suggestions on how to attract them so I can get a picture

Oh, they were small? and eating from a feeder? and one was dead? Well, that’s certainly compelling evidence for not one but two previously unknown hummingbird species in the unexplored wilds of Michigan. Can’t wait to see those pictures.

Einstein was not an entomologist

Male Squash Bee in pumpkin flower

Squash Bees are among approximately 4000 species of native bees (and thousands of other native pollinators) in North America.

If the bee disappeared off the face of the globe then man would have only four years of life left. – Albert Einstein

The quote above, as the caption to a photo of a honeybee, is making the rounds on Facebook. While I appreciate the environmental sentiment behind it, there are several serious problems:

  1. There’s no evidence that Einstein actually said or wrote this. It wouldn’t be the first time someone tried to bolster a statement’s credibility by misattributing it to a famous dead person.
  2. Even if he did, he was a physicist, not an entomologist or pollination ecologist. Being a genius in one field doesn’t make someone an instant expert in another. I’d be far more impressed if this quote was attributed to Steve Buchmann, but regrettably few people have heard of the University of Arizona’s eminent bee ecologist.
  3. “The bee” suggests that the quote refers to the honeybee (Apis mellifera), as we would understand that “the horse” refers to domestic horses and “the dog” refers to domestic dogs. There are thousands of other species of bees, and many of them are important to agriculture. North America’s native flora and indigenous agriculture got along quite well before European colonists introduced the honeybee, thank you very much.*
  4. I’m going to belabor the previous point, because I find it really annoying when people use “the [generic singular noun]” to make sweeping generalizations about large and diverse groups, e.g. saying “the hummingbird is the world’s smallest bird,” when many hummingbirds are larger than many small songbirds. AARGH!**

It’s hard to overstate the importance of pollinators, but too many people obsess over the honeybee without understanding their dark side. Yes, the decline in honeybee populations in North America is causing problems, mostly for beekeepers, the farms that use their services, and people who eat a lot of honey. From environmental and public safety perspectives, however, the decline isn’t necessarily a bad thing. As important as they are to agriculture, honeybees take food out of the mouths of native pollinators and present a real danger to people, pets, and livestock.

From most of the southern U.S. through Central and South America, the feral (“wild”) honeybee population carries genes from highly aggressive African strains that have earned them the nickname “killer bees.” Though virtually indistinguishable from pure European honeybees, Africanized bees attack en masse when they sense a threat to their hive. Even a single sting from any honeybee can be fatal to those allergic to their venom, but Africanized bees often sting their victims hundreds of times. You don’t have to be allergic to die from such an assault, and many people have. They also defend a larger area around their hives and will chase perceived predators farther than their European cousins do. Where these aggressive bees are known to occur, it’s prudent to assume that any feral honeybee hive is Africanized and give it a wide berth.

Native bees are excellent pollinators and nowhere near as dangerous to people and pets as honeybees. They already do much of the pollination work in our gardens, as long as some natural habitat remains nearby to support their nests and other ecological needs. If farmers are going to make effective use of native bees’ services, they’ll need to reduce field sizes and pesticide use and create mosaics of cultivation and native vegetation, and that’s also a good thing for thousands of other insect species plus birds, mammals, reptiles, etc. that can’t survive in our current agricultural wastelands.

References: Native Bees of North America

Science Daily: Bees, Fruits and Money: Decline of Pollinators Will Have Severe Impact On Nature and Humankind

Science Daily: Honeybees May Not Be as Important to Pollination Services in the UK, Study Suggests

Science Daily: Native Bees Could Fill Pollinator Hole Left By Honeybees

Science Daily: Wild Pollinators Support Farm Productivity and Stabilize Yield

Montana Wildlife Gardener: Build a Mason Bee House in 5 Minutes

* Even if all bees of all species disappeared, we’d still have thousands of other pollinator species that fill similar ecological niches, including wasps and flies. Also, loss of pollinators wouldn’t directly affect crops that don’t need pollination: wheat, corn, rice, and potatoes come to mind.

** A FB commenter tried to defend the quote by claiming that the quotee was using “the bee” to refer to all pollinators(!). If so, why wouldn’t the quotee just say that explicitly? In fact, the history of the quote per suggests that it originated with French beekeepers, which supports the assumption that “the bee” in question is the honeybee.

Search of the Week: “is molasses ok to feed hummingbirds”


Feeding stations in southeastern Arizona attract rare beauties such as Lucifer Hummingbirds with plain old sugar water.

NO. Molasses (and brown sugar, which contains molasses) is absolutely not safe to feed hummingbirds. It’s high in iron, for which nectar- and fruit-eating birds have a very low tolerance. When hummingbirds consume more iron than their natural diet provides, the excess builds up in their organs and kills them slowly and painfully.

As I’ve covered here before, there are only two things that are absolutely safe to put in your hummingbird feeders: white sugar and water. Just add 1 part white granulated sugar to 4 parts good quality water. Stir until dissolved (no boiling necessary). Adding to or substituting for this recipe could put their health at risk, and what intelligent, caring person would want to do that to a hummingbird?

But since there have been so many searches like this lately, let me repeat and expand the list of things that don’t belong in hummingbird feeders:

No-sign-20px Honey
No-sign-20px Molasses
No-sign-20px Any non-white sugar, including brown, organic, “raw,” turbinado, “natural,” Zulka Morena, colored baking sugars, and evaporated cane juice
No-sign-20px Powdered sugar (which contains anti-caking ingredients)
No-sign-20px Pancake syrup, maple syrup, or agave syrup (misleadingly marketed as “nectar”)
No-sign-20px High-fructose corn syrup (e.g., Karo Syrup)
No-sign-20px Artificial sweeteners (Sweet ‘n’ Low, Equal, Splenda, or their generics)
No-sign-20px Natural nonnutritive sweeteners (stevia derivatives such as Truvia, Stevia In The Raw, various others)
No-sign-20px Anything containing artificial or nonnutritive sweeteners
No-sign-20px Artificial food coloring, including but not limited to Red #40 and Red #3
No-sign-20px Anything containing artificial coloring (including most “instant nectar” and “hummingbird food” products)
No-sign-20px Anything containing sodium benzoate or other preservatives (including most “instant nectar” and “hummingbird food” products)
No-sign-20px Protein or vitamin supplements (protein powder, pet bird vitamins, dried insects, etc.)
No-sign-20px Jell-O or similar products
No-sign-20px Kool-Aid, Crystal Light, or equivalents
No-sign-20px Gatorade or other sports drinks
No-sign-20px Alcoholic beverages of any kind
No-sign-20px Carbonated beverages of any kind
No-sign-20px Caffeinated beverages of any kind
No-sign-20px Fruit juices (except a small amount of concentrate added to sugar water for color, if you must)
No-sign-20px Beet juice or other vegetable juices
No-sign-20px Lemonade, limeade, or other fruit-based beverages
No-sign-20px Coffee, regular or decaf
No-sign-20px Teas, whether black, green, or herbal, regular or decaffeinated
No-sign-20px Dairy products or substitutes
No-sign-20px Vegetable oils
No-sign-20px Soup, broth, or consommé
No-sign-20px Vanilla extract or other natural or artificial flavorings or extracts
No-sign-20px Essential oils or herbal extracts
No-sign-20px Perfumes or other fragrances, whether natural or artificial, designer or fake
No-sign-20px Colloidal metals, including silver, gold, platinum, uranium, plutonium, and unobtanium
No-sign-20px Anything other than pure white granulated sugar and good-quality water. 



HOAX: Gum does NOT kill birds

BOGUS: Gum does not kill birds

This blatantly manipulative hoax keeps going around and around and around Facebook, and I’m beyond sick of it. One version currently has 8,725 shares, even though people have debunked it over and over in the comments. It’s frustrating as hell to see a debunking comment followed by a string of “aw, poor birdie” comments, then another debunking and another string of… well, you get the idea.

No one seems to be taking credit/blame for this garbage, but the originator is an idiot who’s needlessly upsetting goodhearted people.

There are three huge problems with this image:

  1. Wildlife biologists and rehabilitators don’t report birds dying from gum clogs (Google it).
  2. Birds aren’t so stupid that they can’t tell gum from bread (which they shouldn’t be eating either).
  3. The birds in the photo are swallows, which eat only insects, and the dead one has been hit by a car.

There are valid reasons to toss chewing gum in the trash instead of on the street, but saving birds isn’t one of them. Please don’t “like” these posts, don’t share them, and inform any friends who share them that they’re perpetuating a hoax.

Search of the Week: “are hummingbirds poisonous?”


Small animals that are poisonous or venomous often sport bright colors to warn away predators. This doesn’t apply to hummingbirds.

No. Where it’s legal to do so (not in the U.S., where they’re protected by federal law), you could eat as many hummingbirds as you want without suffering any ill effects.

What’s that? Oh, you meant venomous. No, they’re not venomous, either. If they were, I’d know, because I’ve handled thousands of ’em.

Beet sugar: maybe a myth, but not debunked

The latest edition of BirdWire, the monthly electronic newsletter published by Bird Watcher’s Digest, features longtime contributor Kevin Cook busting bird myths. Naturally, I had to click the link to see if Kevin tackled any hummingbird myths. He did, but…

The “myth” he took on is about beet sugar. Some hummingbird aficionados use only cane sugar because they claim the birds can tell the difference. I’m not convinced that this is true, so I was excited about the prospect that someone had conducted field tests to demonstrate that hummingbirds have no preference. Unfortunately, Kevin based his debunking on much flimsier evidence. He wrote:

Kitchen research in which neither cooks nor overseeing researchers knew whether they were using beet or cane sugar repeatedly showed no difference in the outcome of desserts based on the origin of the sucrose.

Taste buds, whether hummingbird or human, cannot tell beet sugar from cane sugar.

Brown Violetear

Gratuitous hummingbird photo (because I know what you crave).

Wait… what? Humans are humans, and hummingbirds are hummingbirds. There’s even a significant difference within our own species in the density of taste buds and the sensitivity to strong flavors (look up supertasters). Unless you’re putting liquified tiramisu in your feeders, how the two sugars perform in desserts has no bearing whatsoever on how hummingbirds perceive them.

What we need (and still don’t have) to debunk this myth (if myth it is) is a double-blind study presenting the birds with solutions of the same concentration in similar feeders in randomized positions, etc.

Sounds like an excellent science fair project.

Orange-throated hummingbirds: Not so mysterious after all

The gorget of a male Ruby-throated Hummingbird in mid-September.

The gorget of a male Ruby-throated Hummingbird in mid-September consists mainly of older orange feathers with a few fresh red ones.

Note 1: This post is about orange throats in normally red-throated male Ruby-throated Hummingbirds. If you’re trying to identify a hummingbird with an orange throat, start with Rufous Hummingbird. For additional hummingbird ID help, please refer to A Field Guide to Hummingbirds of North America in the Peterson Field Guide Series.

Note 2: This is a blog post, not a peer-reviewed article, and I’m personally acquainted with the people mentioned. Therefore, I’m dispensing with the artificial formality of referring to them by their last names.

The late-season color shift in hummingbird gorgets, a phenomenon familiar to hummingbird banders, has caught the attention of David Sibley. Unfortunately, a red herring had David barking up the wrong tree (it was an arboreal herring).

The source of the misdirection is an article in the September 2009 issue of Birding, “The Alternate Plumage of the Ruby-throated Hummingbird,” in which Donna Dittman and Steve Cardiff documented late summer/early fall molt (another phenomenon well known among hummingbird banders, though apparently none were consulted for the article). Extrapolating from Donna and Steve’s contention that Ruby-throated Hummingbirds undergo a more-or-less complete fall molt into “alternate” plumage (only to molt again in late winter—a dubious scenario), David hypothesized that the orange gorget color observed in some male Ruby-throateds in fall and winter is acquired by molt and constitutes a dull winter plumage. Comments from hummingbird banders Cathie Hutcheson and Scott Weidensaul encouraged him to reconsider, but I’d like to take this opportunity to review what we do and do not know about seasonal color changes in hummingbirds.

Though they don’t fade in the way pigment-produced colors do, the iridescent colors of hummingbirds do change over time. The exact mechanism by which this happens has yet to be documented (at least in published form), but the short answer is that it involves wear and/or bleaching rather than an additional complete molt.

To get to the long answer, it helps to know a bit of the science behind the colors. Iridescence is produced by thin layers of substances of different refractive indices, such as a film of oil on water. The refractive index is the speed at which light passes through a substance; it’s responsible for the bent appearance of a pencil in a glass of water. Refractive index values are based on the speed of light through a vacuum, which is assigned a value of 1. The higher the number, the slower the speed. The refractive index of air is 1.000293, water’s is 1.3330, and that of ordinary glass ranges from 1.523 to 1.925.

In the feathers of hummingbirds, layers of microscopic bubble-filled discs of melanin, known as platelets, are the primary source of the refractive and interference effects that create the birds’ brilliant colors. According to Crawford Greenewalt (1960), the refractive indices of the melanin and the bubbles are 2.2 and 1.0, respectively. Different colors are produced by variations in the relative thicknesses of the melanin matrix and the bubbles (the average refractive index). Thicker melanin (higher average refractive index) pushes the iridescent color toward the red end of the spectrum; larger bubbles (lower average refractive index) push it toward the violet end. Using a spectrophotometer, Greenewalt found an average refractive index of 1.85 for hummingbird feathers that iridesce red and 1.5 for those that appear blue. Following the order of colors in the spectrum, a green feather’s average refractive index would fall between 1.5 and 1.85, while the value for a violet feather would fall below 1.5.

Anna's Hummingbird gorget showing wear

Anna’s Hummingbird gorget showing shift to coppery orange on exposed distal portions of the feathers and retention of fresh hot pink color on basal portions protected by overlying feathers.

In his follow-up post, David points out that a change in wavelength from red to orange would require a change in the thickness of the platelets. He imagines this as a collapse, but physical abrasion and/or degradation by exposure to sunlight seem like far more plausible explanations. This is supported by detailed examination of individual feathers, which show a color shift on more exposed parts and the original color on more protected parts (illustrated in the photo at right).

The change in refractive index may result from thinning of the feather’s outer layer of transparent keratin (refractive index = 1.56; Osorio and Ham 2002), complete removal of the keratin layer and abrasion of the melanin matrix of the top layer of platelets, or changes in porosity that alter the refractive index of the keratin and/or melanin. Any of these would lower the average refractive index of the iridescent structures and push the color toward the violet end of the spectrum. Over time, a feather that started out bright red would be expected to shift to orange, yellow, and perhaps even green as more of the higher refractive index material (melanin and/or keratin) is removed or degraded, and that’s what we see in nature (even in the less intense green iridescence of the back feathers, which tend to be more golden green in spring and more emerald in fall).

There’s little doubt among hummingbird banders that the shift from longer to shorter wavelengths is the result of wear and aging rather than molt, but only electron microscopy of fresh and worn feathers can reveal the mechanism responsible. I don’t personally have the resources to pay for specimen preparation and EM imaging, but if someone with deeper pockets and/or university connections can provide the microscopy services I’m sure I can round up some feathers.

Addendum 1: Another photo of a male Anna’s showing the color contrast between extremely worn and new crown feathers.

Anna’s Hummingbird crown in early fall, during replacement of gorget and crown feathers.

Addendum 2: A macro photo of a male Anna’s gorget at the beginning of gorget molt. The purple/fuchsia feathers at the bottom edge are new. The color shift on the older feathers is most dramatic on the barbs, which are more exposed than the barbules.

Anna's gorget molt and wear

Click on the image to view at full resolution. ©2015 Sheri L. Williamson.


Dittmann, D. L. and S. W. Cardiff. 2009. The Alternate Plumage of the Ruby-throated Hummingbird. Birding 41: 32–35. Part 1 Part 2

Greenewalt, Crawford. 1960. Hummingbirds. (Dover reprint, 1990.)

Osorio, D. and A. D. Ham. 2002. Spectral reflectance and directional properties of structural coloration in bird plumage. Journal of Experimental Biology 205, 2017–2027. link