Issue 10 | 13 June 2021
Greetings, trivia-trawlers of the internet. Welcome to the 10th issue of the Curiosity Catalogue.
Like the last issue, this one’s been delayed. I’m still trying to figure out a schedule with the new job that allows me time to write this without being perpetually glued to the screen. Coming issues might be similarly unpredictable. I think one issue every three or four weeks might be the norm from now.
I suppose that’s okay. I certainly don’t want to give this up - it’s my biggest creative outlet and a motivation to stay curious. But I also don’t want this to become a chore I dread. So, less frequent, but still alive. That’s a balance I’m okay with.
Bird-Brained Brilliance
For this issue, I look to the sky. Well, I look to the work of others who’ve looked to the sky to understand the world of birds and their miraculous movements.
Their migration has fascinated people for millennia. It’s like - birds. One season they’re here. Another they’re not. Magic. (As silly as this sounds, it wasn’t far off the mark. Read on).
Before humans could move across the earth with ease or follow birds with tracking technology, knowing where they went was impossible. Still, curiosity demanded an answer, and in the absence of evidence, they indulged in fanciful explanations at the very least, if not outright fantasy.
Aristotle, for example, thought some birds hibernated in winter (entirely plausible) while others turned into entirely different species (a little less plausible). Thousands of years later, Europeans didn’t know much better. The 16th-century cartographer Olas Magnus believed that birds buried themselves in clay on riverbeds. Charles Morton, a 17th-century English scientist, offered perhaps the most extravagant theory of all; birds made a quick annual trip to the moon and back (he literally said “Now, whither should these creatures go, unless it were to the moon?”). At that time, no one knew the Moon didn’t have much gravity or an atmosphere, so it seemed like a pretty decent place to for a holiday for winged creatures.
A pain in the neck
Our earliest proper understanding of bird migration began in the 1820s. It started with a German Count shooting a stork flying overhead, only to discover that it had been hit earlier - it had a spear running through its neck, and had flown this way for quite a while.
Scientists at a local university figured the spear was African in origin (though they didn’t know where in Africa). With this, they had concrete evidence that birds traveled from place to place, sometimes even with spears sticking through their necks (about 25 more like were found after that).
Migratory miracles and mysteries
In the last few centuries, we’ve learned a lot more about these migrations. For one, we know with some certainty that birds stay within our planetary realm. We also know where many of them go and why (for better weather, to mate, for food, etc.). As a whole, though, the process is still a minor miracle; Kathryn Schulz perfectly summed up why:
“Consider the bar-headed goose, which migrates every year from central Asia to lowland India, at elevations that rival those of commercial airplanes; in 1953, when Tenzing Norgay and Edmund Hillary made the first ascent of Mt. Everest, a member of their team looked up from the slopes and watched bar-headed geese fly over the summit. Or consider the Arctic tern, which has a taste for the poles that would put even Shackleton to shame; it lays its eggs in the Far North but winters on the Antarctic coast, yielding annual travels that can exceed fifty thousand miles. That makes the four-thousand-mile migration of the rufous hummingbird seem unimpressive by comparison, until you realize that this particular commuter weighs only around a tenth of an ounce. The astonishment isn’t just that a bird that size can complete such a voyage, trade winds and thunderstorms be damned; it’s that so minuscule a physiology can contain a sufficiently powerful G.P.S. to keep it on course.”
She continues
A bird that migrates over long distances must maintain its trajectory by day and by night, in every kind of weather, often with no landmarks in sight. If its travels take more than a few days, it must compensate for the fact that virtually everything it could use to stay oriented will change, from the elevation of the sun to the length of the day and the constellations overhead at night. Most bewildering of all, it must know where it is going—even the first time, when it has never been there before—and it must know where that destination lies compared with its current position
Researchers think the in-built-GPS birds are blessed with might be influenced by the Earth’s magnetic core, through a process called magnetoreception. Parts of their bodies, possibly beaks or eyes, contain a mineral called magnetite, with which they can sense magnetic waves from the Earth and develop an internal compass of sorts.
That’s one theory, at least, but it’s by no way definitive. The science on this is uncertain and too complicated for me to comprehend. I won’t make authoritative statements on this; instead I recommend you read Kathryn Schulz’s piece I quoted from above, and watch the video below.
What I will mention here is a fun fact about Robins that Ed Yong wrote about. Robins, as it turns out, are born with a sensor in both eyes which helps them navigate, but lose the use of the one in their left eye as they grow up. They need to see for this sense to work, so if you cover the right eye of a fully-grown robin it will lose its way when flying, but not if you cover its left eye.
In addition to this navigational prowess, birds seem blessed with an equally miraculous memory. Many, after migrations that span several months and thousands of kilometers, return to the very same tree they first left. Some winged creatures (I’m not sure whether this applies to birds) have intergenerational memory. Monarch butterflies - no heavier than a piece of tissue - fly from New York to Mexico and back every year. The thing is, the lifespan of an individual butterfly isn’t long enough to complete the journey. Instead, through an inter-generational relay race, they move further and further north, and simiarly back South. All in all, one migratory cycle is a job for five generations.
Safety from the storm
As fascinating as the internal mechanism of avian migration might be, it isn’t an isolated event or process. It’s closely linked to the rhythms of nature and has to respond to changes in ecological patterns. Weather, in particular, impacts long-distance migration a lot, and birds have to be finely tuned into weather patterns to time their departure just right.
I’m thinking specifically about the Veery, a small brown bird documented in the first episode of Connected. Veeries spend their summers in the USA and winters in Brazil (ah, what a life to live). Their nesting season (when they raise chicks) is generally around summertime in the forests of the USA. Once done with this, they fly to Brazil.
They leave the USA between the end of June and mid-July, but when they leave in this period makes a big difference. The longer they stay, the better their chance of raising chicks successfully. (Having seen baby birds hatch on my terrace, I can testify that two weeks is a long time in this life-cycle. Just last week, I saw a baby bird that went from hopping to flying in two days). If staying longer means healthier offspring, then why leave early?
The answer, as I’ve already sort of given away, is the weather. While flying, they cross the Gulf of Mexico during hurricane season. They seemed to have a sixth sense (well, seventh, if you count the internal compass) about how bad the hurricane season is going to be, and time their departure to avoid the worst of it.
Just think of that - they can sense weeks or months ahead of time what the weather is going to be like. This is nothing short of a superpower, especially when you consider that no human weather predictions, even with the fanciest of supercomputers, make predictions with such precision. Looking at over 20 years of data, the Veeries were more accurate. In 2018, for example, humans predicted a below-average hurricane season, while Veery migration hinted at severe hurricanes. Until August, it seemed like human predictions would win out. In September and October, Central and North America was battered by four severe hurricanes, and 2018 became one of the worst years for hurricanes on record.
Oh, the humanity
As human action often does to nature, we’ve threatened this miraculous practice of avian migration in the last few centuries. Forest destruction is an obvious cause - we either push them out of their homes or destroy them while the birds are elsewhere (imagine returning from a holiday to find your home replaced by a shopping mall - that’s what entire species go through because of humans).
Climate change messes with weather patterns they depend on, and as we saw in the case of the Veeries, can harm their nesting season. Warmer temperatures also mean that food sources for these birds often move beyond their current migratory zones; these birds arrive ravenous after extremely long journeys often to find their dinners have moved away.
Our cities also get in their way. Glass buildings kill and injure millions of birds every year. City lights illuminate the night skies confusing birds that depend on star positions to chart their course (yep, some of them are astronomers as well). In rural areas, pesticide usage can impair their sense of direction and cause them to lose their way.
If bird migration wasn’t already enough of a natural miracle, the fact that it happens despite human intervention is definitely miraculous. How long they can keep at it, we can’t be sure. It is, of course, in our collective power to help them, if we so choose. To quote John Green from The Anthropocene Reviewed,
“…we are nonetheless their biggest threat—and also their best hope. In that respect, we are a kind of god—and not a particularly benevolent one.”
The Round-up
My inspiration for this issue came from a wonderful poem about birds and their journeys written by my friend, Kartika Menon. You can read it here. Kartika also guest-wrote issue Issue 7 of the Curiosity Catalogue.
I read and heard some absolutely amazing material while researching this, and have linked most of it in the piece. From these, I’d particularly recommend you read the Kathryn Schulz piece from the New Yorker, and listen to the episode of Radiolab below (There and Back Again, 18 Dec 2019.)
My information for flawed early ideas on migration came from an essay in Matt Simon’s former column in WIRED called Fantastically Wrong. The entire archive of these is filled with wonderfully fanciful misconceptions the human mind has come up with over time.
I’ve recently been reading and loving The Anthropocene Reviewed by John Green, which I quoted just above. It’s a collection of essays where he reflects on aspects of the anthropocene, this era where humans reign supreme on planet earth. He finds great insight in the most mundane of objects, sees wonder in a piece of music or cinema (including the opening scene of The Penguins of Madagascar), weaving his own life stories in and out of the narrative when necessary.
The essays in the book were originally episodes of a podcast by the same name. You can get it wherever you listen to things, and I’d highly recommend you do (start with You’ll Never Walk Alone and Jerzy Dudek from May 2020)
I love YouTube: As I did last week, I’m sharing two channels I love from YouTube. The first is Johnny Harris’ channel, where he talks in-depth about exactly the sort of trivia-y stuff I’m into (plus a whole lot more). He was also the creator of Vox’s amazing Borders series. The second is VlogBrothers, a channel actually run by John Green and his brother Hank, with content ranging from personal reflection to life experience to well, just a lot of wholesome video.
About me: I’m Shantanu Kishwar, a lover of fun trivia and well-made hummus. Feel free to follow my sporadic updates on Twitter and Instagram.
I hope you liked this issue. If you’re new here and want the next straight in your inbox, subscribe above. Feel free to reply with thoughts, recommendations and suggestions. Do share this with other curious people you know. I’d really appreciate it, and hope they will as well.