Killer hummingbirds revisited

sherlock-holmes

“It’s a photo of a dead hummingbird! What do you make of it Holmes?”
“Impossible to say without additional evidence, Watson.”

Periodically over the nearly nine years since the publication of Killer hummingbirds?, I’ve received comments from people taking issue with what they believe that post says. Typically, these readers have witnessed an attack by one or more hummingbirds on another and wish to inform me that I’m wrong to say that hummingbirds never kill each other. The first problem is that I didn’t say “never,” and they would know this had they read as far as the bold black text in the middle of the post:

 “Only birds weakened by hunger, disease, or injuries… are vulnerable to injury and, in rare instances, death from other hummingbirds…”

Some of the reports clearly fit the qualification above, because, to quote more of the original post:

a healthy hummingbird will either defend itself or flee before a more aggressive individual gets the chance to do any significant damage.

Others provide few if any useful details of the event, even when prompted, and still others are just accounts of finding a dead hummingbird and assuming, because they had previously observed combat, that it was a case of trochilicide.

This brings us to the other problem with these reports, which is that they are never accompanied by any objective evidence—photos or video—that would support their accounts of the events (much like reports of yellow hummingbirds). A recent correspondent claimed to have seen a Black-chinned Hummingbird…

“…physically stick his bill deeply into another h.bird’s belly, twice! Then 2 more times into the back of the others neck.”

There are a couple of problems with this description as evidence of hummingbirds fighting to the death, even if one combatant is severely disadvantaged. The first is that poking is rather common in hummingbird combat, and the disappearance of the tip of an aggressor’s bill into the thick plumage of the “victim” would be understandably alarming to someone unfamiliar with hummingbird anatomy.

BCHU-bouf-brain

A hummingbird poking another’s body with its bill is a bit like someone poking Marie Antoinette in the bouffant with a knitting needle.

The second is that, even when the bill passes completely through the feathers and makes contact with the other bird’s body, hummingbird anatomy makes a fatal penetrating wound highly unlikely except in freak circumstances (see page 23 of A Field Guide to Hummingbirds of North America for an example).

This X-ray CT image of a Ruby-throated Hummingbird, showing its huge, deeply muscled rib cage, short skin-and-bones neck, and virtually nonexistent “belly,” demonstrates why hummingbirds are not as vulnerable to penetrating wounds as humans are (or as capable of inflicting them):

CT scan of a Ruby-throated Hummingbird. Copyright Digimorph.org

CT scan of a Ruby-throated Hummingbird. Copyright Digimorph.org

The issue of hummingbirds injuring one another in combat took a fascinating twist in 2014, when Alejandro Rico-Guevara of the University of Connecticut and and Marcelo Araya-Salas of New Mexico State University announced their discovery that the unusual bill shapes of adult male Long-billed Hermits make them more effective at inflicting potentially painful puncture wounds than the bills of females and juvenile males, and that males with longer, pointier bill tips were more successful at defending territories.

These revelations were newsworthy precisely because the bill shapes of the vast majority of hummingbird species, including all of the familiar North American species, show no such adaptations and confer no apparent advantages in combat. It’s also noteworthy that while the researchers observed male Long-billed Hermits poking each other during combat, they did not mention observing any serious injuries, much less fatal ones, resulting from these interactions. In fact, most of the “fighting” shown in their video consists of belligerent posturing and vocalizing with little physical contact, similar to the combat behavior of most North American hummingbirds:

(Note that the black-and-white segment depicts two non-hermit species, and the last sequence depicts courtship and mating, not fighting.)

So now we have compelling evidence that males of at least one hummingbird species have bills adapted for use as “stabbing” weapons, yet documentation of fatal encounters between healthy, normal hummingbirds is still almost as elusive as Bigfoot. I expect it will remain so, but I’m open to persuasive evidence.
Decreux LikenessesResources:

Rico-Guevara, Alejandro, and Marcelo Araya-Salasb , 2014. Bills as daggers? A test for sexually dimorphic weapons in a lekking hummingbird. Behavioral Ecology 26(1): 21-29.

Digimorph.org: Archilochus colubris, Ruby-throated Hummingbird by Dr. Ronald Stearman, The University of Texas at Austin.

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New post at my Web site

WN-Jacobin

I’m such a bad blogger. I didn’t even post about my spectacular trip to Trinidad and Tobago last summer where I photographed this stunning White-necked Jacobin.

Has it really been almost a year since I last posted here? I’m still working on the second edition of A Field Guide to Hummingbirds of North America, so I haven’t been doing much writing otherwise, but I did just add a post to the News tab on my Web site about a controversy that erupted during the spring 2012 Ruby-throated Hummingbird migration. Hope you enjoy it!

P.S.: If you’d like to see more of my photos from Trinidad and Tobago, check out the album on Flickr.

“Chemical-free” sugar?

My reply to the following e-mail bounced, so I’ll answer it here:

I’ve read the first part of your article on hummingbirds about what  to make when you feed them.

Before reading the article, I just made hummingbird food with organic sugar. I am concerned about the addictive and other chemicals in white sugar. Is there any white sugar available on the market that does not contain chemicals?  or a way to transform organic sugar in white?

Thank you for your time.

In the strictest sense, there is no product of any kind on the market that doesn’t contain chemicals. I’ll need to know what specific substances you’re concerned about (other than iron) before I can answer your question, but the way it’s phrased suggests that you may have fallen victim to fear-mongering hyperbole about white sugar. In that case, this post may be helpful:

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

One feederful of organic sugar isn’t going to kill hummingbirds because the iron concentration is very low. It’s chronic exposure to excess iron over weeks, months, or years that may cause illness and death. Unfortunately, there is no simple home remedy for removing the residual iron from organic/”raw”/turbinado sugar.

Search of the Week: “hummingbirds won’t eat instant nectar”

Lucifer Hummingbird female

All of Arizona’s famous feeding stations use plain sugar water to attract avian celebrities such as Lucifer (above, female), Magnificent, White-eared, and Violet-crowned hummingbirds. (photo © Sheri L. Williamson)

Maybe they’re trying to tell you something. Most of the “instant nectar” and “hummingbird food” products on the market are adulterated with petroleum-based artificial dyes and/or preservatives, so it’s safer if the birds don’t eat them.*

Even products that claim to contain natural coloring aren’t necessarily trustworthy. On a recent visit to one of the big-box pet stores, I encountered three versions of a brand of “instant nectar” touted on the Web as containing “natural red coloring.” The ingredient list showed that the concentrate and one of the two powders contained FD&C Red No. 40, which has been found to cause harm in laboratory animals at dosages substantially lower than a hummingbird would be exposed to by drinking one of these products. The label on the other powder listed beet coloring, which may not be the best choice of natural coloring for hummingbirds for reasons I explained in an earlier post.


* The few “instant nectar” products that don’t contain unnecessary and potentially harmful additives may not hurt the birds, but they’ll put an unnecessary dent in your bank balance. They’re ≥99% sugar priced at five to ten times what you’d pay for white granulated sugar at the grocery store. What you’re really paying for is the colorful, “convenient” package, not a better product. If you’ve got cash to burn, try superfine or caster sugar, which dissolves more quickly in cold water than regular granulated. Organic sugar, “raw” sugar, and “evaporated cane juice” are other pricey alternatives that might seem worth the extra green, but their beige to brown color indicates the presence of iron, which is known to be a potentially deadly problem for hummingbirds. Until we know more about how much supplemental iron hummingbirds can tolerate, they’re not worth the risk.

Review: Feeder Fresh Nectar Defender

(Originally submitted at Duncraft, which I do not patronize because it sells various overpriced “nectar” products that contain artificial dyes, preservatives, and/or other potentially harmful additives that don’t belong in hummingbird feeders.)

A bad idea

1out of 5

The active ingredient in this product is reportedly copper, which is an essential micro-nutrient at natural (low) intake levels and a potentially toxic heavy metal at higher doses. The fact that copper accumulates in birds’ bodies combined with hummingbirds’ extreme appetites increases the risk that the copper in this product will accumulate over time to levels that may cause scientifically documented problems such as behavioral changes, developmental abnormalities, reduced egg production and nestling survival, etc. That’s a pretty high price to pay for reducing feeder maintenance.

Search of the week: “how do i know if the hummingbirds are to fat”

When they can’t get off the ground.

Image

To survive their epic migrations, Rufous Hummingbirds may double their body weight by converting energy-rich sugar into energy-rich fat.

Seriously, a wild, free-living hummingbird can’t get too fat. Fat is fuel for migration, and they pack on the grams as necessary to prepare for travel and shed them just as quickly when the journey is over.

Beware the wrath of the birding legions!

A Snowy Owl at Benton Lake National Wildlife Refuge in Montana, safe from murderous bureaucrats and and Silver-bellied Gashawks.

A Snowy Owl at Benton Lake National Wildlife Refuge in Montana,
safe from murderous bureaucrats and and Silver-bellied Gashawks.
CC image courtesy of USFWS Mountain-Prairie on Flickr.

(Title borrowed from a column by the late, great Molly Ivins.)

On Monday morning, the New York Daily News broke a story about the Port Authority killing Snowy Owls at airports in New York City. Follow-up articles contrasted trigger-happy NYC with the more responsible and humane policies of Boston’s Logan Airport (a famous location for wintering Snowy Owls). The story quickly spread via Facebook, prompting a petition and phone campaign to stop the carnage (three owls had already been shotgunned by the PA’s euphemistically named “wildlife specialists” after five others struck planes).

Usually such efforts take days, weeks, or months to bear fruit, and some never do, but by Monday evening the PA had come around and agreed to stop slaughtering the owls and cooperate with trapping and relocation. The outrage from the public, including the birding community, was so swift and so fierce that it overcame bureaucratic inertia.

Every day on social media we see calls to action in support of one good cause or another or against the latest outrage. It’s good to know that raising our voices and signing our names can make a difference.

“Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it’s the only thing that ever has.”  — Margaret Mead