Since 2012, the rainbow lorikeet, an Aussie parrot with clownish coloration, has undergone two mild bouts of internet virality. The first stemmed from the bird's obscene tongue: a thin, purplish tube topped with an explosion of beige hairs designed to absorb their sustenance of choice –– nectar. The notoriety of this brushlike appendage makes it all the odder that, three years later, the birds went viral again when an Australian birder reported that the lorikeets in his backyard had, for the better part of a decade, been snacking on meat.
This second moment of celebrity caught the attention of Paula Zelanko, a chemist at the Academy of Natural Sciences with a habit of using her expertise to investigate personal lines of inquiry; she analyzed her sister's fingernails over months, for example, to track her transition to vegetarianism. Zelanko asked herself the question readers were wondering across the internet: Do these known nectar-drinkers moonlight as meat-eaters?
The difference between Zelanko and the rest of us captivated by the lorikeet? She had the resources to find the answer. Zelanko turned to Nate Rice, the collection manager of the academy's ornithology department, who provided her with several specimens –– some of which he had collected himself in the early aughts and some of which date back to the ornithological pioneer John Gould's early expeditions in the 1820s. Zelanko has run studies since 2015 with Rice's specimens in search of what exactly these birds eat with their lewd Q-tip tongues.
To understand Zelanko's findings, which so far indicate that the lorikeet diet might as well reflect Robert Mitchum's favorite slogan ("Beef … it's what's for dinner"), you need a working knowledge of her brand of chemistry.
When CSI and other crime shows send off samples to an amorphous "lab" to see whether, say, a trace of crime-scene car paint matches the bumper of the suspect's SUV, they are sending the sample to someone like Zelanko. Her primary job consists of operating two pieces of equipment: the sci-fi-sounding "elemental analyzer" and the "mass spectrometer," a monster-sized piece of khaki-color technology that roughly amounts to a glorified scale.
To run a study like this, Zelanko takes a solid sample –– say, a fingernail or a chunk of bird feather –– washes it (to remove any oils that might skew analyses), and feeds it into the elemental analyzer. At an ultrahigh temperature, the analyzer releases a puff of oxygen. In a burst of bright light, the sample combusts and turns into gas.
"There's a little viewing window to watch the sample combust," Zelanko says. "You don't see the feather. You see the brightness of it –– there's a flash." From this gas sample, the elemental analyzer isolates carbon and nitrogen, the sole elements accepted by the academy's mass spectrometer.
Understanding the "mass spec," as Zelanko calls it, requires a return to high school chemistry, where you might have learned that atoms of the same element can vary in number of neutrons. These variants are called isotopes, and though they share the same chemical properties, they have different masses –– a carbon-14 atom, for example, weighs slightly more than a carbon-13 atom, because it has one extra neutron. Detecting that difference is, in a nutshell, the job of the mass spectrometer. Aptly named, the machine uses the mass of a sample to identify what isotopes it contains.
This ultimately proves much more interesting than it sounds, because the kinds of isotopes found can say a lot about the source –– that a suspect's car was at a crime scene, for example, or that a scientist's sister has given up meat. In dietary studies like Zelanko's, carbon analyses can reveal the kinds of vegetation the sample fed on.
"In the carbon world, you can distinguish C3 plants from C4 plants," Zelanko explains. "C3 plants are all your vegetables, your trees, some grasses, some shrubs. Your C4 plants are sugar and corn, and temperate, warm-climate grasses."
Nitrogen analyses, however, can pinpoint with reliable precision where a sample sits on the food chain. As organisms climb the primordial hierarchy of who-eats-what — scientists call these "trophic levels" — the quantities of heavier nitrogen isotopes in their chemical composition also rise.
"Decaying organic matter and plants — that's the bottom," Zelanko explains. "Whatever eats plants is one trophic level higher. Let's say rabbit. Whatever eats the rabbit is another trophic level higher." These higher organisms are composed of their own nitrogen and the nitrogen of all the organisms they eat.
When Zelanko ran carbon and nitrogen analyses of her lorikeet samples, she found indication of C3 vegetation ("Not that exciting," Zelanko concedes, "there's probably just not much C4 vegetation in that region") –– but the nitrogen results sent her reeling.
If the lorikeets fed primarily on nectar, their nitrogen isotope composition should be fairly low, as nectar is not high on the food chain.
"But these [data points] span a whole bunch of trophic levels," Zelanko says, gesturing to a scatter plot whose values are, quite literally, scattered. "That's crazy. Just looking at this, it looks like they are getting their nitrogen from something other than a plant source."
Still, Zelanko hesitates to draw conclusions. The lorikeets she sampled come from environments across Australia –– so there's a chance her Jackson Pollock-ish scatter plot merely represents their natural variation.
"I could run isotopes on osprey [specimens] from everywhere over the country," Zelanko says. "Even though they're all from the top of the aquatic food chain, they're all going to be different –– because the bottom of the food chain varies in different places. So, I need to see if this [distribution] is realistic for nectar-eaters."
In other words, Zelanko needs to compare her data with another nectar-drinking Australian bird. If their values are equally wide-ranging, the results can be attributed to variance in environment. But if not, these flying rainbow Popsicles are probably eating flesh.