Angry Birds, Part 2: Sinister Songbirds

While it is relatively easy to think about massive, belligerent, hook-jawed, feathered monstrosities like the giant petrel, skua, and lammergeier as being kin to the long-extinct therapod dinosaurs, creatures solidly employed in the “flesh-rending-death-beast” profession, perhaps a little harder to grasp is the notion that commonplace little tweety birds have the capacity to be pint-size brutes. But there are certainly some shining star examples that I’ll outline here.

When I refer to “tweety birds”, I mean birds of the order Passeriformes, which are known as the “songbirds.” Robins, sparrows, meadowlarks, finches, orioles, crows, swallows, wrens….everything from Big Bird to Woodstock….Red Robin to the Arizona Cardinals…all of them are passeriform birds. They are members of by far the most diverse order of birds, and with more than 5,000 species, they are among the most speciose of any vertebrate order. They are distinguished from the other groups of birds by, generally speaking, their exquisite control of the syrinx (a vocal organ that is analogous to our own larynx) to generate elaborate bird songs. They are also notable for being a group of animals that has their evolutionary roots placed in a part of the world that is far more frequently noted for having endemic creatures that do not ever leave; Australia and New Guinea. It’s thought that these little guys first broke off from the rest of the flock roughly 50 to 60 million years ago in this arm of the old southern continent of Gondwana (which was isolated then just as it is today) and somehow exploded onto the world stage, rapidly diversifying and eventually finding themselves in all imaginable locations and habitats.

And it is in Australia that the first entry on this list makes its home.

Johnny Two-tone up there (the one who apparently shares an eye-color with Darth Maul) goes by the name of “Australian magpie” (Cracticus tibicen, if you’re nasty), and it’s easy to see why. The black-and-white ensemble (often referred to as a “pied” coloration) and wedge-shaped beak is dead ringer for the magpie bird that many people from the northern continents are familiar with. However, the two birds are not all that closely related, and the pigmentation pattern is a coincidence of convergent evolution. True magpies are in the crow and jay family (Corvidae) and while they are highly-intelligent and mischievous animals, they aren’t particularly aggressive birds, favoring wiley methods of scavenging and hanging around urban and suburban environments for human food waste. In contrast, the Australian “magpie” is a member of the Artamidae family, which is a group of crow-like birds native to the continent and surrounding islands, and the family is far more closely related to other Australasian, Southeast Asian, and Madagascan birds, like vangas and ioras, than they are to the corvids.

It’s also worth mentioning that the genus to which the Australian magpie belongs, Cracticus, is full of birds collectively known as “butcherbirds.”
So, you know we are off to a good start.

Butcherbirds are so named for their unabashed serial killer habit of capturing prey (usually insects and small reptiles) with their sharp beaks, and then shish kebabing the poor little bastards on thorns or sharp branches. They then keep the unfortunate souls there until they are done consuming them…piece by piece. Butcherbirds don’t really have the strong talons that full-sized birds of prey possess, so they can’t really hold down their meals while they tear it to shreds; so, that’s what the skewer is for. It acts as an anchor for them to get some torque when they start incrementally de-limbing the miserably contorted carcasses. These little grand displays of savagery are known as “larders,” and they not only serve as a means of storing food for later, but they also are meant to attract mates. Because nothing gets the lady birds all hot and bothered like fetid corpses of the innocent hung up in your crib like Monet prints.

“Hey girl, I got a big, decaying lizard at my place. It’s a February 2014, great month. Wanna see it?”

This trophy-making bloodsport isn’t specific to one sex, but it’s thought that the larder of the male is potentially the one that is up for judgement. The idea is that if the male can acquire a varied and plentiful collection of flesh decorations, he might also be good at other things *wink wink* *nudge nudge*…meaning of course that he’ll have the capacity to help provide for offspring and pass on decent genetic material…get your minds out of the gutter.

So, after a precursory inspection by the female, some awkward small talk, and maybe a final dose of internal bargaining, if the female is down with it, they settle down and make their own set of chubby-cheeked war criminals. The two parents feed and care for the young after this, but they often get plenty of help from other closely related birds of the same species in the area. This is that “cooperative breeding” thing I was talking about with skuas in Part 1. It seems to be that in particularly clever species that require a long childhood full of learning and complex behaviorally development, whether they be butcherbirds, crows, chimps, dolphins, or humans, the “it takes a village” mentality is heavily applied to the rearing of youngin’s.

And an extended childhood it is for butcherbirds. The juveniles end up staying with the mother for a very, very long time. Well past the ability to fly and care for themselves do they completely “fail to launch.” Young butcherbirds that are all but full grown and sexually mature tag along with the mother throughout the day, whining at her whenever she catches food so that she’ll give them some, and she obliges, further spoiling the jobless brat.

“Sounds familiar. I have a good-for-nothing man-child…I mean “butcherbird”…at home myself.”

Australian magpies are just a big, lanky versions of a butcherbird. They differ in a few ways, one of which being that they don’t really engage in that whole macabre feng shui shit the other members of the genus are really into.
But they, like other butcherbirds, also have that devotion to parenting on lock down.

In fact, it’s their extremely “passionate” disposition towards caring for and defending their eggs and chicks that have given these birds, already hailing from a clan of vicious mini-raptors, a reputation as one of the more hostile and bellicose birds on the Australian continent. In the Australian spring, between about late August and the start of October, the season for egg hatching comes around in Australian magpie circles. With this lovely season comes…swooping. Swooping is not a fun dance move. Swooping is not slang for taking an even funner recreational drug. There is nothing enjoyable or cute or happy about swooping. Swooping is fucking terrifying. Because swooping is when birds make it their goddamned mission to scare and/or maim anything and anyone that dares get too close to the blind, squeaking larvae-like hatchlings…and this is achieved by precision air strikes against the vulnerable skulls of would-be predators. Humans are very much not exempt from being targets of this behavior.

I’ve been swooped before. Not by an Australian magpie, but by a common crow. I was walking towards Amazon Park from the university neighborhood one pleasant, sunny, summer day in Eugene, Oregon, not a care in the world…when I suddenly heard a loud whoosh and felt wingtips clip the side of my ear. A crow had given me an intentionally close buzz, from behind and off to the right. I say “intentionally” because I had no idea it was even there, and if it had been calling at me to stay clear, I wasn’t paying attention; that crow could have easily drilled it’s beak into my crown and I wouldn’t have seen it coming, and I’m very sure it knew that. The close call was more than enough though. After ducking, screaming, and waving my arms above my head for a few seconds, I regrouped and made it obvious to the brainy, angry bugger that was circling around for a second “warning” that I took the hint by jogging another block and a half down the street….keeping my eyes on the ominous black form above that trailed me that entire distance before turning around and flying back to its tree. After realizing I was out of harm’s way, and cleaning the shit out of my shorts, the experience ended up having a fairly profound effect on how I thought about crows going forward. And I wasn’t even pecked or hit. And it happened only once.

I can’t imagine what Aussies put up with, because once the annual Spring of Discontent rolls around Down Under, Australian magpies take it to the next level. Well, I should say some magpies do. Technically, it’s only the males that do the swooping, and it’s only like one in ten (roughly) that actively engage in the more extreme behaviors. However, Australian magpies are ubiquitous across the continent, and where they are found, they exist in fairly high-densities, where the birds tirelessly defend their territories. They are wonderfully adapted to urban and suburban living as well…so you might, at this point, be getting a sense of why even if only about 5-10% males swoop, if their numbers aren’t hampered dramatically by the entirety of metro Sydney developing on Australian magpie turf…there might be some conflict down the road.

Blue = places where Australian magpies try to kill you,  Pink = places where EVERYTHING ELSE tries to kill you, because Australia

The Australian magpie, now a dutiful new dad, upon noticing an unwitting pedestrian or cyclist intolerably close to the nest usually sends out reasonable warnings. A close approach. A bit of angry chatter. Hopefully, the hapless human isn’t absorbed by their cell phone or MP3 player at the moment, because if the fair warning is not heeded, things escalate really fucking quickly. The Australian magpie does not forgive, and ignorance of the first bit of “communication” is not a valid defense on your end.
The second level of domestic defense involves actual swooping…which means dive-bombing the back of your head at full speed, and then pulling up or to the side with just enough room to gouge and snap at your noggin or ears. Reason help you if the Australian magpie decides to swoop from the front, because all of the sensitive, important parts of your mug are fair game. That wicked sharp triangle on the front of its head? That’s the business end of a screaming smart missile aimed at the part of your face where your eyes are. That’s what Cracticus tibicen has in store for you.

My Latin’s a little rusty, but I’m pretty sure the “tibicen” means “bringer of pain”

If you happen to share a neighborhood with a few particularly “difficult” Australian magpie bros, your life, for five weeks out of the year, can easily morph into something that would make the ghost of Alfred Hitchcock very, very proud. Your nice, afternoon stroll through Indooroopilly can, at a moment’s notice, be interrupted by a fire-eyed fell-beast, screaming out of the suburban heavens, with a one-track mission to disband your jelly-filled peepers from their sockets and carry them off like olives speared on a cocktail skewer. Understandably, many folks have tried to figure out a way to dissuade the minority of aggro magpies from playing Stabby Stabby with the scalps of the innocent. Some people put sunglasses on the back of their head, because they think the extra pair of eyes will “frighten” the birds and keep them from striking at the skull (not sure why this method is even bothered with, considering that Australian magpies seem to have precisely zero issues with going for the eyes). One common way bicyclists have attempted to deal with swoopings is to attach long, sharp “spines” all over their helmets, the idea being that bristling with anti-bird armament would, er, “persuade” against close approaches. I’m not joking. Aerial barrages from Australian magpies are so damn hazardous to human health that, fully embracing Australia’s Mad Max-ian heritage, people have resorted to running around with goddamned spiked helmets.

Somewhere, Mel Gibson is smiling…but not about this. Probably about something racist.

Sadly, these defensive efforts (which I like to call “hedgehoging”) are largely ineffective against Australian magpies, and quite frankly, your typical “problem” male magpie couldn’t give two dusty fucks about the half-assed arts and crafts project on your head. His genetic legacy rests in the survival of those little, chirping, pink, featherless, scrotum-skin covered lumps of joy back in the nest, and without fearlessness in the face of animals hundreds of times more massive, wearing a Stegosaurus-tail helmet or not, that legacy is far more likely to be cut short. Evolution has crafted a behavior composed 100% out of pure, unadulterated “I-don’t-give-a-fuck”, and there’s not enough pipe-cleaners and fire stokers in the world that can stop it.

Perhaps the most unsettling thing in all of this is that more often than not, a given Australian magpie isn’t indiscriminate in its righteous anger. It’s not like every single person, young or old, male or female, is equally at risk of being assaulted. For whatever reason, nest-defending magpies tend to be a little…bigoted…and bafflingly, randomly so. Maybe the magpie on the corner of Broomfield and Murray spares little old ladies, but festers with a deep, birdy hatred for boys between the ages of 7 and 12. Perhaps the magpie on 33rd and Fig Tree couldn’t care less about middle-aged dudes walking their golden retriever mixes…but 20-something women jogging with their Weimaraners? Oh HELL no. Some burn with unrepentant loathing towards only cyclists, or just the neighborhood mail carrier (referred to in Australia as a “postie,” because that country has an adorable slang nickname for everything).

This specificity of targets among males that do engage in swooping could be random fixation, but the narrow prejudice might have its origins in a form of social learning. The adoption of learned behaviors among individuals in a social group, in particular the wariness of select targets, is something that has been observed in similarly intelligent birds like American crows. In this example, knowledge of the identity of a particular threatening human was disseminated throughout the social network of crows, mimicking the propagation of ideas, stories, and concepts we see in human cultures. This precedent of “education” exists in crows, so it may not be far-fetched to wonder if young Australian magpies are taught what passersby are of primary threat based on the actions of their fathers, and then, following the same vertical, generational transfer of bigotry seen in human society, repeat the same aggressive behaviors (or simple tendencies) once they reach fatherhood themselves.

The abject terror induced on the unluckiest of Aussies is nothing but persistent, and while the onslaught from the skies can be as minor as a heart-jumping nuisance, the danger from these types of attacks has the potential to be truly great. Like I’ve said, swooping Australian magpies routinely aim for the eyes, and people have been blinded before. In fact, eyes are the most frequently affected body part from magpie attacks, being affected in an estimated one-fifth of attacks that cause some sort of injury.
Even more seriously, Australian magpie attacks have even indirectly resulted in human deaths. In 2010, a 12-year old boy died when he ran into traffic desperately trying to evade a swooping magpie, and was struck by a car.

Because of events like this, Australia is a place where there is serious public debate about the line between upholding wildlife conservation and human safety for not only things like “problem” crocodiles…but, as weird as it may sound, “problem” birds as well.
Meanwhile in the U.S., this the closest thing we have to this conversation is typically limited to the occasional snappy dog, or perhaps a bear that keeps wandering a little too close to campgrounds in a National Park.

Australian magpies are certainly not the only songbirds with a twisted, violent streak, and while they are notable for funneling their aggression towards human beings, there are many others that are restricted to simply picking on critters their own size. One group of birds intimately familiar with being the bane of the existence of diminuitive creatures the world over are the shrikes (pictured above).

While there are several groups of unrelated birds called “shrikes,” in this instance I am referring to birds in the family Laniidae; a group of big-headed, robin-sized birds armed with stumpy, formidably hooked beaks that are found primarily in Eurasia and Africa, and far less so in North America. Taxonomically, they are a grouped within the Corvoidea, meaning that birds like crows and birds-of-paradise are among their closest relatives. Most species tend to frequent open, grassy areas, which allows them, like the birds-of-prey they resemble tiny versions of (with comically infantile body proportions), to scan their domain for unwitting prey. They don’t have the grappling-hook talons of actual birds-of-prey, so they utilize components of their environment to get a “handle” on their living, animated prizes, inevitably destined to be of the “culinary” variety. How do they do this? Do they fashion miniature ropes and baskets out of dried grass to restrain their prey? Maybe they collect tree pitch to make their feet all sticky? Aww.

No. They do not do these things. Not even fucking close. Shrikes take the bodies of their comestible conquests and shove them onto a sharp thorn or stick until the entirety of the depth of their little, lifeless (hopefully) figures is inelegantly transfixed in place. Like a toothpick in a cheese cube hors d’oeuvre. But with more blood. It is in this way that the shrike can capture larger prey, like a small mammal, reptile, or a particularly beefy bug, and hold it in place so that it can incrementally shred it into little chunks with its paring knife of a beak. The act of harpooning large bits of food in this manner, typically in places out of the reach of many other food thieves, also provides a long-term strategy via forming a sustenance cache. If you’ve been reading this entry with any sort of comprehension, the above explanation should sound quite familiar to you. These “larders” are incredibly reminiscent, in both function and appearance, to the grim methods used by Australia’s butcherbirds (described above), and it is perhaps no surprise that shrikes are often referred to as “butcherbirds” themselves. This similar dietary quirk evolved independently in these two groups of birds, miraculously enough, and is a powerful example of convergent evolution, which is often easily observable in physical traits (limb shape, for example), but not typically adequately appreciated in complex behaviors…such as making a larder.

Well…it certainly isn’t appreciated by the mice and lizards that share their home with shrikes, and understandably so.

Mr. Jingles has had better days.

Flitting around and merrily Vlad-the-Impalering every soft-bellied thing in sight, and then greedily saving the spoils for ages later seems like an effective evolutionary strategy all on its own…but it turns out, in at least one instance, there are hidden, unintentionally acquired benefits to engaging in this hectic life of stab-‘n-go.

As you (should) know, not all critters are exactly easy to eat, even when hopelessly cornered or in the grip of their attacker. Some have gargantuan, re-curved claws, married to an on-command adrenaline flood that un-cages otherworldly fury and strength. Some are festooned in venomous barbs and are lit up with more brilliant, psychedelic warning coloration than a Burning Man art installation. Others bloat up like someone shoved a tire pump up their ass, getting so aggressively turgid in their devourer’s craw that they pinch off all incoming lines of life-sustaining oxygen, ensuring that if they are going down, goddamnit if they don’t get some last minute, fatal karmic justice.

And others still are more subtly hard to ingest, at least permanently so, arming their very essence to the gills with powerful cocktails of toxic chemicals, and providing hints to would-be diners through a godawful overall taste and flashy colors…which mean to clue predators in on how they are a worse gastronomic decision than luke warm, gas station sushi. This advertisement of one’s own severely inedible nature is known as an “aposematism”, and is basically an ever-present neon sign reading “do what you want, man, but there are better ways to end your life…I’m just sayin’…”

One of these walking wads of poison is the lubber grasshopper (Romalea guttata), a massive, orange and yellow monster of a grasshopper longer than a man’s finger native to the southeastern United States. As an adult, its wings are too undersized for flight, and it can barely hop worth a shit, and spends its time clumsily fumbling over vegetation, looking more like an inebriated land shrimp than one of its spring-loaded, field-dwelling cousins.

If you are a bird, somehow literate and reading this (I know you’re out there…I’m lookin’ at you, Big Bird), the description of a 3-inch bug, practically crippled by its own damn fatness, probably sent a stream of drool immediately out of your beak. But trust me, lubber grasshoppers work really fucking hard at making themselves as unappetizing as possible. When confronted with the imminent threat of being unceremoniously inhaled as a mid-afternoon snack, they go into “don’t-eat-me-I’m-actually-really-off-putting-and-gross” mode. The grasshoppers let out a hellacious hiss, spit, and begin to foam with copious amounts of white, toxic foam from pores in their mid-body. The foam itself is bitter to just about every creature that gets a mouthful of it, and typically that’s enough to earn a prompt expulsion from the jaws of death. If the grasshopper is successfully swallowed by a particularly brave and/or desperately hungry predator, the sinister amalgamation of toxins embedded in the body of the grasshopper (high doses of quinones, phenols, and various poisonous compounds derived from the very plants the grasshopper feeds on) all come together as digestion starts, resulting in a vigorous assault on the digestive system of the diner…an animal that is now surely burdened with immediate, stomach-roiling regret. Lubber grasshoppers tend to be swiftly barfed back out before digestion can be completed, and the predator, now shamed and nauseous, will think twice before giving the bulky, tangerine-colored temptations another go.
It is because of their effective chemical defenses that lubber grasshoppers can “afford” to be giant sacks of delicious buggy goodness, propelled by legs too flimsy to evade threats and a brain too chillaxed to give a shit about finding a place to hide. If just about anything tries to eat them, that poor son of a bitch is going to have a really bad time. Lubber grasshoppers are free to bumble around their little world, largely blissfully ignorant of the terrors that haunt their more tasty brethren and lead them to dart between the shadows.

Yeah, yeah, we get it. You’re practically immune to predation. You don’t need to keep showing off.

But, despite the lubber grasshopper’s seemingly air-tight toxic defenses…there remains a loophole…one that the shrike has managed to exploit through simply doing what shrikes do best…sticking bug carcasses on really pointy things.

Lubber grasshoppers are substantially-sized insects, and can definitely fuel a bird like a shrike over the course of a couple of days. If the shrike makes an attempt at consuming any part of its newly-deceased, spike-bound quarry, it reacts like it took a shot of battery acid up the snoot; lots of hilariously adorable head-shaking, spitting the food right back out, and totally avoiding a second taste. However, if the grasshopper larder is left to sit for a day or two, ripening in the summer sun like a head rotting on a Medieval pike…the game totally changes. Apparently, the effectiveness of the lubber grasshopper toxins declines precipitously after death (a property of chemical compounds called “lability”, in which the compound in question, typically a protein, is susceptible to alteration or degradation outside of ideal or in vivo conditions), meaning that the shrikes can then safely consume the grasshopper. They age the grasshoppers on thorns like a fine, crunchy wine, and once they’ve reached the right stage of decomposition, the shrikes feast, enjoying the bountiful reward for their delayed gratification.

This loophole might be enough to lead to evolution of defensive traits in lubber grasshoppers in places where their range overlaps with that of the shrike. If their toxicity is a completely ineffective deterrent to a major predator in their neighborhood, simple chemical defenses may not provide the same level of protection (and contribution to overall fitness), on its own, that it does in places without shrikes. You would expect, given enough time, that in places where this overlap between shrikes and lubber grasshoppers occurs, lubber grasshoppers would, on average, have more effective alternative predator avoidance traits. Maybe they’re quicker, can jump higher, more likely to take shelter away from open areas, less likely to congregate in big groups, etc. There would be greater selective pressure from the presence of shrikes to have more in their defensive “tool box” than just toxins.

It’s like if you lived in a really bad part of town, but felt confident walking around at all hours of the day and night with a truly top-notch bulletproof vest on. It works pretty well, and protects you from the common bullet from time to time, but if one day, a bunch of people start running around with flamethrowers…your key defense is no longer of any use. You better find some fire-retardant clothes or learn how to run faster or your goose is cooked…so to speak. Just like the lubber grasshopper, your carefully constructed master plan is only as good as how universally it applies to all potential threats.

The lubber grasshopper isn’t the only animal to co-opt chemicals from their environment and concentrate them into potent forms for their own use. The strategy is used in multiple groups of insects, including ants, beetles, and butterflies. The oceans are full of examples of toxin adoption as well, either as an evolved tool for defense (specifically known as toxin “sequestration”), or as an accident of diet. Filter-feeding shellfish like clams can easily concentrate dangerously high levels of neurotoxins in their tissues by feeding on microscopic, uni-cellular algae (dinoflagellates), which is why people are strongly cautioned against eating shellfish collected during a “red tide” algal bloom, or immediately following one, since the intake of toxic algae by the shellfish is off the charts during this period. A similar situation can occur in various groups of tropical and sub-tropical predatory fish (most commonly things like barracudas, mahi-mahi, groupers, and moray eels), wherein toxic dinoflagellate algae are consumed indirectly by herbivorous fish, the toxin is concentrated in the tissues of the fish, and numerous herbivorous fish are then eaten by predators, and on and on up through the food chain, with the concentration of toxins ratcheting up exponentially with each trophic level (a process known as “bioaccumulation”), culminating in a kind of potential food poisoning of unwitting fish-eating humans commonly called “ciguatera.” Various kinds of sea slugs take in toxins from their diet, and re-purpose them as an anti-predator defense.
On land, among vertebrates, the most famous example of powerful defensive toxins derived from diet comes from the poison dart frogs of Central and South America (family Dendrobatidae). For many years, it was pretty much accepted that poison dart frogs got their toxins (powerful alkaloids, among the strongest of which is batrachotoxin (BTX)) from external sources found in their native range, since frogs reared in captivity do not end up producing the toxin, and frogs introduced outside of their native range (like Oahu’s Manoa Valley, the wide-bottomed rainforest valley from which I am typing this blog entry at this very moment; a small, introduced population of green and black poison dart frogs (Dendrobates auratus) resides here) do not end up being poisonous either. There were various suspects for the toxins’ origins considered, including merylid beetles and secondarily toxic ants, but in 2007, the primary contributor to diet-derived toxins in poison dart frogs was more or less nailed down as a group of mites. Poison dart frogs take the lubber grasshopper’s strategy of sequestering toxins to a whole other level; among the several most potently toxic species (which are also widely regarded as possibly the most poisonous animals on the planet…so there’s that), a single individual’s skin glistens with enough toxin to put the entire starting lineup of the Seattle Seahawks six feet under. They also have the appropriate levels of warning coloration to match, and the group, generally speaking, are gifted with the most intensely vivid colors in nature found outside of coral reefs.

There are also a very small number of reptiles (snakes in particular) that appear to sequester some toxins from their food (often toxic amphibians like newts and toads), but do not use these compounds to envenomate prey…rather, the toxins become saturated in their bodily tissues. These are in fact actually poisonous snakes, rather than venomous snakes.

But there are another, perhaps unexpected, group of animals outside of the hundreds of insects, scores of fish, piles of amphibians, and the few reptiles with representatives known to take in deadly toxins from their diet and use them for their own benefit. I am, of course, talking about birds.

The fellow photographed above, and looking a bit like the spirit of Halloween incarnate, is a pitohui, specifically a hooded pitohui (Pitohui dichrous). There are six species of pitohui, and all are exclusively found in the isolated (and threatened) rainforests of New Guinea. They are members of a family of songbirds known as the Pachycephalidae, a group of rainforest birds collectively known as “whistlers” that are commonplace throughout Australasia, many Oceanic islands, and parts of Southeast Asia, and are representatives of an ancient radiation of early songbirds in the region. Even more generally, this family of birds is a part of the proposed clade of Corvoidea…one of four major subdivisions of songbirds, and one that, if you’ll remember from earlier in this entry, curiously, also includes the Australian magpie and the shrike.

As far as rainforest birds go, pitohuis are outwardly unremarkable. They are omnivorous foragers, and don’t have any obvious adaptations that distinguish them from anything else with feathers that flits sporadically between tree branches.

So what’s actually so special about these birds? They are poisonous. Pitohuis are fucking poisonous birds, and just like lubber grasshoppers and poison dart frogs, they steal their toxins from their meals. These toxins, undoubtedly originating from some secondarily toxic insect, are then incorporated into the skin and feathers of the pitohui.

I know some eyebrows might be raised at the mention of a bird without any appreciable violent tendencies filling the final slot on a two-part series on so-called “angry birds”, but hear me out when I say that the position awarded is well-deserved. Just as I characterized the super-scavenger lammergeier as an avatar for the Grim Reaper and as an agent of a more subtle form of darkness, the pitohui’s intrinsic, chemical perniciousness makes its very body the site of a kind of molecular hostility. Pitohuis therefore fill the role of passive aggressiveness within this suite of “angry birds.”

The pitohui’s poisonous plumage wasn’t appreciated by Western science until 1989, when then graduate student John Dumbacher, in New Guinea as a part of a team studying birds-of-paradise, accidentally made the discovery while removing an entangled pitohui from a mist net (a common tool for facilitating the capture/collecting birds in the field). The little guy, understandably, fought for his life while being extracted from the net, and apparently did a number on Dumbacher’s hands with its sharp beak and claws. Upon putting the wounds up to his mouth, Dumbacher found that his lips and tongue began to burn and tingle. Tasting a feather later on led to the same sensation, which lasted for a long while afterwards. It wasn’t until a few years later that the toxin sizzling and sparking on inquisitive scientists’ tongues in New Guinea was identified, remarkably, as batrachotoxin…the same toxin produced by poison dart frogs.
Yes, what would eventually be considered the most striking example of toxin sequestration in birds was initially discovered by scientists sitting in the jungle, licking birds like a goddamn ice cream cone, and wondering what the fuck was making their mouths light up like they just took shots of Pop Rocks and chili powder.

I say “most striking example”, because there are other examples of poisonous birds (albeit precious few), although none of them generate the toxins by themselves, and instead adopt the compounds from dietary sources and concentrate them in their muscles, organs, skin, and feathers. Among them is a close relative of the pitohuis (found in the same family, also from New Guinea), the little shrikethrush (Colluricincla megarhyncha), which is not a shrike…or a thrush…and only carries the hybrid common name because apparently ornithologists are really, really bad at coming up with original names for birds. Like its close cousins, the nondescript, drab gray little shrikethrush has feathers and skin that are doused in potent, sequestered batrachotoxins. There is also the blue-capped ifrit (Ifrita kowaldi), a charming, colorful forest bird also native to New Guinea with a common name that is evidently an onomatopoeia of the sound you make when you try to hold in a sneeze…also a bearer of toxin-laden integument, and again, it is batrachotoxin used as the chemical weapon.

There are also a number of other examples of birds that become toxic from their diet, but do not re-route these compounds into their feathers and skin, and rather simply become a noxious meal for a predator, as their meat and viscera are tainted with poison. Perhaps an example of this phenomenon with the most renown and extensive acknowledgement throughout recorded history is coturnism, a form of food poisoning resulting from eating common quail (Coturnix coturnix), native to parts of Europe, that previously eaten large amounts of toxic plants. Consumption of various kinds of plants has been proposed as the main culprit for the…er…de-edibilization…of a frumpy, brown bird that looks like it hardly waddle in a straight line, let alone cripple a human with illness by way of its own flesh. Common suspects include henbane, hemlock, or hellebore, all of them toxic to humans. Coturnism is apparently not a recommended “bucket list” experience to live through. The toxins immediately kick the ever-loving fuck out every muscle in your body in a process called rhabdomyolysis. Simply put, this means that your skeletal muscle, the big ones that help you move around, are partially degraded and destroyed by the toxin. Bands of muscle fibers rapidly deflate and liquefy like an Otter Pop in the summer sun. If the level of rhabdomyolysis is relatively light, your entire body will feel like you spent yesterday doing 14-hours of weight training interspersed with getting hit by a semi-truck or five. If it’s serious, the massive influx of waste in your blood from your dying muscles can cause your piss to turn the color of Dr. Pepper and can even lead to rapid kidney failure. So, there’s that.

The ailment was common enough, and had enough impact, that it pops up throughout recordings from Antiquity, ranging from observations from ancient Greek and Roman naturalists, to anecdotes in the Bible (Numbers 11:31-34) wherein people eat a lot of quail, and end up a lot of dead.

Another example is the Carolina parakeet (Conuropsis carolinensis), a marvelous, golden-headed bird that was once the world’s most northerly ranging parrot species, and graced the skies of America’s plains states, Southeast, and up along the eastern seaboard until freakin’ New York…until it went belly up for good in the early 20th century. It’s extinction was ultimately the result of an anthropogenic twofer; massive amounts of deforestation and habitat loss after European colonization, and the exploitation of the birds for their feathers, which were used to adorn women’s hats in the decades proceeding the demise of the species. Because nothing is more fashionable than irreversible biodiversity loss.

Anyways, these birds were generally considered to have poisonous flesh, and eating them was understood to be a risky endeavor. They were known to be voracious consumers of cocklebur seeds. Cocklebur (Xanthium) seeds are also incredibly toxic to mammals, so the concentrated toxins in the meat of the parakeet proved to be an issue for humans or anything else (like cats, which would routinely die shortly after catching and eating these birds) that tried to get a little taste. The seeds themselves still prove to be an issue, since cocklebur is an invasive plant, and the seeds can certainly harm livestock that accidentally eat them wherever the plant ends up invading.

So, sure, inadvertent concentration of toxins from food sources that happen to be toxic to predators doesn’t necessarily tell an adaptive, evolutionary story in the same way that the sequestering of toxins for specific, alternative use does…as in the pitohuis, ifrits, and shrikethrushes. But why? Why has this trait, seemingly bizarre among birds, this ability to transfer toxins from toxic insects (which got their own toxins from the plants they eat) to skin and integument, evolved in the first place?

In the past, it was assumed that the poisonous feathers and skin were a defense against predators, just as the similarly acquired batrachotoxins in poison dart frog skin were. However, as I’ve outlined above, poisonous animals usually have some means of advertising their unpalatable nature, and this is usually conveyed through intense warning coloration. Hooded pitohuis have the highly-saturated colors typical of aposematism, but the blue-capped ifrit and the shrikethrush are not all that vividly pigmented by bird standards.

It’s also very worth noting that, being nimble forest birds, these creatures don’t live at the same pace typical of animals that use toxins as a deterrent against predators…the lubber grasshopper I wrote about above is a perfect example of how opposite this lifestyle is to that of the known poisonous birds…which, being birds, have the capacity to quickly and efficiently fly the fuck away from danger. You see starkly different predator evasion abilities in toxic animals (or animals with defensive venoms), because these animals don’t need to be agile, or even particularly worried about potentially getting gobbled up. The same tends to go for animals with armored plating or sharp spines; for example, the porcupine does just fine shambling slowly along, since few things are going to bother messing with it anyways. So why would something like the ability to make poisonous feathers evolve in one of the most mobile groups of animals on the planet?

The answer may be that the batrachotoxin in pitohui skin and feathers is an adaptation against parasite infestation. In fact, non-toxic feathers have been shown to be favored over pitohui feathers by lice, implying that the “target” for the toxin isn’t a giant snake, coiled in wait in the rainforest canopy, or a laser-sighted eagle, but potentially the smallest, most nagging micro-predators. But being able to shed oneself of parasites is not a trivial advantage. The cumulative effect of just ectoparasites like ticks, fleas, and lice can sap energy and blood from the host animal, and leave it susceptible to weakness and secondary disease. Living in Hawai’i, I am quite familiar with the effect that parasites and parasite-like insects can have on vulnerable bird species; native birds in these islands have had their populations decimated by the spread of avian malaria, which is transmitted through introduced mosquitoes. The unfortunate ultimate result is an abrupt and jaw-dropping fall in endemic bird diversity in the archipelago over the past couple hundred years. Toxin-laced feathers could certainly be a boon to overall fitness in the face of such potentially far-reaching impacts of parasites and any infectious organisms they harbor.

It’s also thought that we’ve seen some precedent for this before in a fairly different group of animals, this evolutionary strategy of using chemical defenses in the skin, hair, and/or feathers as a means of controlling parasitic infection. In particular, I’m thinking of the slow loris (Nycticebus), a sloth-like primate related to the more familiar lemurs, found across South and Southeast Asia. Slow lorises produce a toxin in glands located in the armpits. This poison, far too strong for even Old Spice to tackle, is activated by saliva when licked, and then groomed into the fur by action of the teeth. The poison is also used in its bite, where the chemical hugs special grooves on the teeth, and in the moment of a hypothetical bite, the slow loris technically has a venomous bite…the only primate known to have one, and one of an incredibly select handful of mammals known to envenomate attackers or prey via the chompers. It’s worth noting that the populations of ectoparasites inhabitating the fur of slow loris are generally depauperate compared to those of other primates, suggesting that there is some utility of the venom-fur application as an extreme form of bug spray. It is feasible that this anti-parasite strategy evolved independently, using entirely different compounds and toxin acquistion mechanisms, in Pachycephalid birds like pitohuis and shrikethrushes. That tingling, burning, and numbness from the batrachotoxin being absorbed into your hand when you touch a pitohui might be an accidental misdirection from the toxin’s “intended” target…a group of skin-eating, blood-slurping insects smaller than the head of a pin.

“This is the first and last time you touch me, giant, two-legged louse.”

It’s also possible that toxin sequestration, or at least the evolutionary legacy of it, is far more common in some groups of birds than we thought. There is some evidence to suggest that how we understand how pitohuis are related to one another is currently completely inaccurate, and that many of these species actually are representative of several, distinct genetic lineages that place them in wholly different genera within the Corvoidea subgroup of passerine birds, meaning that the pitohuis aren’t a “natural” grouping. It is significantly less likely that toxin sequestration evolved independently several times among “pitohuis” and is more likely that a common ancestor for the group had evolved toxicity, and that Corvoid birds in general, some 700 or more species, either have the capacity to become toxic (assuming some change in diet), or secondarily lost the trait due to evolutionary change, and that the ancestral, “default” condition for this huge grouping of songbirds is one where poisonous feathers are made possible by borrowing toxins right from the food they eat.

So, consider that not only are the shrikes and Australian magpies (both Corvoid birds), mentioned at the beginning of Part 2, soul-crushing, hyperaggressive, feathered projectiles of claws and hatred…but they might be part of a grand family of birds with chemical weapons built right into their goddamned hides, and the ability to exterminate innumerable troublesome, parasitic invaders by simply touching them. Evolution may have just allowed many of them to “forget” how to utilize the toxins, from a physiological standpoint. This also means that there are potentially many other living Corvoid birds that sequester toxins, but this trait just hasn’t been discovered yet, either due to the assumption that birds do not have poisonous plumage, or because the toxins aren’t anything that humans would notice themselves (like the strong batrachotoxins of the pitohuis).

We share our world with thousands of species of dinosaurs. They might be smaller than the archetypal concept of a proper dinosaur in many of our minds, but despite their beaks and feathers, they are close relatives of the largest, most impressively terrifying land predators in Earth’s history…animals that, no matter their size, where more or less a whirlwind of teeth, claws, rigid bone, and taut muscle. It should be no surprise that many of the therapod dinosaurs that survived and flourished into the present day would also possess the same unforgiving temper, truculence, and cold-hearted, predatory nastiness that made their extinct relatives so successful for so long. From the puke-prone giant petrels, to the epic, bone-throwing lammergeiers, to the callous, tyrannically surgical shrikes, to the criminally insane skuas, the berserk, paranoid, face-stabbing Australian magpies, and the insidiously deadly, fluffy insulation of the pitohui…the spirit of danger, rage, and appetite for carnage lives on in our modern dinosaurs.

Image credits: Angry grackle intro imagemagpie standing, butcherbirds, mad dad,  Australian magpie distribution map, magpie beak, shrike in tree, shrike with mouse (Marek Szczepanek), lubber grasshopperhooded pitohui in tree, held pitohui

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

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5 thoughts on “Angry Birds, Part 2: Sinister Songbirds

  1. Pingback: Boxfish: Little Fish, Big Toxins | Shit You Didn't Know About Biology

  2. Pingback: Venomous and Underrated: Hymenopteran Horrors | Shit You Didn't Know About Biology

  3. Hi Jacob
    You are definitely one for putting the wind up potential visitors to Australia however you missed the snakes (7 of the worlds 10 most deadly apparently) and the spiders like the redbacks that live under toilet seats and the funnel webs that can envenomate through an adult human’s thumbnail. All is not bleak however, our magpies are as intelligent as crows and ravens and quickly become household pets if offered a bit of ground beef (mince in Aussie terms) They are extremely territorial and will fight to the death. Most territoriality is demonstrated by song and family groups in full throat are a joy to hear. Our Butcher Birds, both Grey and Pied are also highly territorial and again have songfests to demarcate. The Butcher Birds (known locally as Organ Birds because of their song) are allegedly, the only birds to not repeat while singing, the song is totally random. I’ve had the pleasure to wake to a dawn chorus of birds too numerous to count and it was magnificent. Strangely, I came to this site while searching for info on the Australian Grey Shrike Thrush and its food cacheing habits 🙂

  4. I will point out that lubbers, at least where I come from, are purple and black rather than orange an yellow. Different morph I suppose.

    Awesome article though!

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