Is Red Dye Harmful to Hummingbirds?

"Ye swinging spears of the larkspur, open your wells of gold
And pay your honey-tax to the hummingbird."

-James Oppenheim


The short answer to the question "Is red dye harmful to hummingbirds?" would be a resounding "Yes!" But I intend to give the long answer too. Throughout the world wide web the assertion that red dye injures hummingbirds occurs from hundreds of individuals who've never looked up the peer-reviewed studies of red dyes, while marginally fewer & equally unenlightened souls insist it is all urban folklore & they've been pouring red dye down hummingbirds' throats for years never seeing an ill effect therefore there is none.

Both sides can get testy & make baseless assertions. So while I make my own assertions, I will give a few citations, because fact is, anyone can say anything they wish on the world wide web, & all too often it's all hooey for which there would be no legitimate source to be cited.

Red dye #40 is derived from coal tar or petrochemicals. It might or might not be the least harmful of red dyes, but it's definitely harmful. It is proven to be carcinogenic & mutagenic to animals [Rosenkranz et al, 1990], decreases reproduction rates [Vorhees et al, 1983], increases incidents of cancerous & non-cancerous tumors & lesions internally & of the skin [Lagakos et al, 1981].

Since the most conclusive studies on this subject were done on mammals (rats, mice, guinea pigs, rabbits, & even on humans) but not on birds, it might all be dismissed by mental deficients or vested interests as not applying to hummingbirds. No studies specifically on hummers are apt to be performed. Yet red dyes are associated with tumors in mammals, & hummingbird experts like Lanny Chambers at seem pretty much convinced the increasing percentages of tumors found in hummers is indeed the result of well-meaning but ignorant amateurs feeding vast quantities of red dyes to hummingbirds.

Personally I would not feed to birds or any other animal chemicals proven to be harmful to humans & other mammals, harmful at doses much lower than are in manufactured hummingbird feeds, & I cannot imagine anyone with a measurable IQ would want to feed red dye to hummers, once they do find out the science on this topic.

Borrowing some figures from Trochlid's article on the subject, the daily maximum amount of red dye established by the World Health Organization as safe for humans (7 mg per kg of body weight, i.e., 0.007 mg per g body weight) is vastly exceeded by the amount of red dye which dose hummingbirds when people use manufactured products. So even if there is a safe level of usage as permitted by the FDA, hummingbird products using red dye exceed that margin of safety by magnitudes of hundreds.

A hummingbird weighing 3.5 grams visiting the same feeder daily, fed (for specific example) the Opus nectar solution, is ingesting 0.42 mg of red dye daily (0.12 mg/g body weight), as compared to 0.007 mg/g considered within safety margins for humans. DNA damage in mice begins at daily doses of Red40 at 0.01 mg/g. So hummers are being fed 40 times the amount of red dye known to cause DNA damage, & hundreds of times more than is regarded safe for human use [Tsuda et al, 2001]. Clearly this can't be good.

Red dye #40 is used in the vast majority of manufactured hummingbird feed products, or so they claim. No one monitors them so they could be using & probably are using even less safe dyes; they are apt indeed to be use whatever dye is cheapest on the open market in the given month of purchase & manufacture. Other red dyes (decreasingly safe) including those which are completely banned for human ingestion but are not banned in all other countries & frequently discovered to be even in imported human food products, so whether for human or animal, dye types are used pretty much willynilly, & it is only a pretence that commercial hummingbird nectars always use Red40. Even that isn't actually safe, certainly not safe at the amounts fed, but even supposing it were the safest of all unsafe red dyes, it is not really apt to be the only such dye used.

Some exaggerated things have been said of red dyes such as it causes baby hummers to be born blind or it causes their eggs to become thin & brittle & so break before chicks are finished developing. (Calcium deficiencies can be caused by feeding hummers sugar concentrates greater than recommended, but the fact that these inappropriate nectars also have greater concentrations of harmful dyes is not an added calcium deficiency factor.) There are other myths about it, but the realities are sufficiently condemnatory that hummer aficianados will avoid the majority of commercial preparations, preferrikng to make their own, & for the following reasons do not include red dye in their recipes:
  1. Red dye has no nutrient value so should not be fed to hummers.
  2. All red dyes are categorized as "xenobiotics" the same as other pollutants, & stress the metabolism accordingly [Kuno & Mizutani, 2005].
  3. Red dye masks fermentation making it difficult to assess the freshness of a mixture, encouraging users to risk keeping the mixture beyond its safety margin since it looks okay to them.
  4. A properly designed feeder attracts no additional hummingbirds by coloring the water, so it is a useless additional ingredient. They are attracted to red flowers, not red nectar, so the feeder, not the feed, should be red. In comparison tests of dyed & undyed nectars offered side-by-side in identical feeders, the non-dyed was visited more often.
  5. The potential carcinogenicity, DNA damage, lowered of fertility rates, increase in tumors, lethargy, & other health problems associated with mammals given doses of Red40 far lower than are in manufactured nectar powders, are not worth risking on such small birds.
That is five solid reasons why no one aprised of the facts uses red dyes in hummingbird foods. By contrast there is only one reason red dyes are included in commercial products even so:
  • The pretty color attracts the dollars of well meaning but ignorant amateurs. Since aficianados make their own, there is no marketing impetus to provide a better product for them. Well meaning & easily duped amateurs are the sole customer base.
For the really knowledgeable hummingbird lovers who do not make their own nectar, the brand choice is Best-1, as the manufacturer has a policy of never including anything harmful or useless in their powder mixes, therefore exclude all red dyes.

The Perky Pet Company has come up with a novel marketing angle because of the well-known dangers of Red40 & other red dyes. They advertise an "all natural" hummingbird food with dye made from flowers & insects. The insect-derived dye is carmanic acid, banned in many countries & restricted in the USA, a "natural" alternative to Red40 which is easily as dangerous as Red40 when injested. The flower derivation is amaranth, ie., the exceedingly dangerous Red-2 banned for human use, which is toxic at low levels, causing skin lesions, cancer, & all manner of problems.

The purpose of the Perky Pet product is to be able to use the word "natural" & work around the justified fear of Red40 which is a petroleum product no less than is motor oil. The alternatives are "natural" all righty, but increasingly harmful. The manufacturers don't care; if they did they'd admit the red dye was never for the hummers anyway & just stop using it.

The red dye that would be safe (but still totally unnecessary) is Betanin derived from beet roots. It is expensive & not sufficiently stable when improperly stored (like at room temperature or in bright light on vendors' shelves) therefore the only certainly safe dye is not used. The law does not require these products to be safe for hummingbirds, so they aren't. If they were for human consumption they could not have the same ingredients.

Often manufactures waffle, make excuses, & lie when confronted on this issue. One manufacturer's FAQ addresses the question of red dye safety not by saying outright that it is harmless, but by dancing around the subject. Instead of a yes or no the Opus Hummingbird FAQ promises only that "All red dyes on the market now have been extensively studied & approved by the Food & Drug Administration as being safe for human and animal consumption."

That's a lie because some red dyes the FDA permits only for topical use not for consumption (such as in cosmetics), others are banned for most uses but not all, most have a confused array of bans, restrictions & permitted uses pending review. The FDA acknowledges that Red40 causes thyroid cancer in rats, but because the triggering mechanism may actually be hormonal (red dye has potent estrogenic side-effects) it only indirectly causes tyroid cancer therefore it is allowed for many uses that would be banned if it were directly the cause of the thyroid cancers that result from use of Red40.

FDA inconsistencies of this nature have been called "paradoxical." Some uses were made "permanently" legal in the 1960s based on science that is very outdated. It would require a new Act of Congress to stop these uses; unfortunately when Congress has tinkered with these laws in recent years, it has been to increase rather than decrease permissible exposures because that's what Industry lobbies for.

In other cases the amounts of dyes permitted in human products are set below the level likely to be harmful in human consumption. These limitations do not apply to use in products labeled not for human consumption. The amount of dye in hummingbird feeds is not regulated, & the birds are so small that ounce for ounce they end up being exposed to levels of dyes hundreds of times greater than amounts known to be harmful.

Red40 is already banned or restricted in Norway, Denmark, Sweden, Germany, Belgium, France, Switzerland, Austria, & a few other countries, while Red Dye #3 is banned in Norway. Both are restricted in the USA because they are known to be carcinogenic to animals, to cause hyperthyroidism, to have estrogenic side-effects interfering with reproduction, & cause DNA damage [Dees et al, 1997; Aziz et al, 1997].

Dyes other than Red40 undoubtedly find their way into hummingbird feeds because that industry is essentially unregulated. In humans & rats, Congo Red is associated with cognitive loss & to hasten the disease process in people with Alzheimers disease [Inestrosa et al, 2005]. It has also been shown to cause liver damage in rabbit-based studies, & has many other problems. Red Dye #2 is banned in the USA, Russia, Austria & some other countries, for causing birth defects & sundry other problems. Red40 became the red dye of choice for manufacturers starting in the 1980s after Red-2 was found to be dangerous. Red Dye #4 is also banned in many countries including the US for human consumption.

These dyes -- which are even more dangerous than Red40 -- despite bans & severe restrictions still find their way way into animal food products & most illegally even into human food products. Periodically there is news coverage of yet another human food product found to have one or another of the banned red dyes in it, but no one is even checking products that are not for human consumption.

See also the article
On Never Feeding Hummingbirds Too Concentrated a Nectar


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