Readers’ wildlife photos

My friend Andrew Berry, who teaches and advises students at Harvard and writes about the history of science, is one lucky git. He’s regularly invited to lecture on Harvard alumni and student trips, and just recently returned from a trip to Tanzania and Rwanda. The group saw many things, but Andrew highlights two of them in this post: zebras and mountain gorillas. His narrative and IDs are indented, and you can enlarge his photos by clicking on them.

Here are some photos from a recent trip to Tanzania (Serengeti) and Rwanda (Five Volcanoes National Park).  Rather than submitting a whole slate of safari inevitables (lions, giraffes, elephants, the usual suspects), I am focusing on two especially wonderful species, zebra and mountain gorilla.

Zebras.  We’re too accustomed to seeing zebras, they’re too familiar.  That familiarity has robbed them of the recognition they deserve: as the craziest-, zaniest-, grooviest-looking animals on the planet.  A pony in black & white striped pajamas.  A Martian visiting planet earth would, I suspect, be unimpressed by the range of animal color diversity they encounter: a lot of beiges, and browns, and grays.  The occasional sexually selected bird might raise a Martian eye brow.  But zebras?!  These would have our Martian beaming excited messages home.  We should ponder zebras anew.  Equine escapees from a Keystone Cops jail?  Surreal emanations of a mind capable of traveling far beyond the imaginings of Magritte?   Psychedelic album art from the ‘60s?

These are plains zebra, one of three zebra species.  Zebra taxonomy has over the years been a little fraught – what constitutes a species, what a sub-species? — but today the plains zebra is classified as Equus quagga.  This seems at first sight anomalous because the Quagga was traditionally presumed to be an extinct zebra relative.  Limited in its distribution to South Africa, the last known Quagga died in Amsterdam zoo in 1883.  The Quagga’s striping was decidedly half-hearted – it lacks that full-on B & W commitment of the true plains zebra.

JAC: A preserved but extinct quagga (Equus quagga quagga) from Wikipedia:

It might look distinct and fail to compete on the striping front, but the Quagga is in fact merely a form of the plains zebra.  Ancient DNA sequencing studies from museum material reveal that Quaggas are nested within the plains zebra family tree, meaning that Quaggas and plains zebras are members of the same species.  What, then, should we call the combined species?  Here the rules of Zoological Nomenclature come into play.  When two groups are combined, we use the *oldest* name that was applied to either of them.  In this case, the first formal description was of Equus quagga.  The plains zebra was formally designated Equus burchelli in 1824, but the Quagga was named E. quagga as early as 1785 by the Dutch naturalist Pieter Boddaert (who was in frequent correspondence with Carl Linnaeus, the Swedish father of modern taxonomy).  And, in taxonomy, precedence is based on antiquity: old trumps new, even when “new” is 1824: all plains zebra, including the Quagga, are E. quagga.   “Quagga” apparently derives from the Khoikhoi word for zebra, which is onomatopoeic, resembling the quagga’s call.

Why the stripes?  A recent paper describes this as a biological problem “with too many solutions.”  A recent review concluded that there are no fewer than eighteen hypotheses out there to explain zebra striping!  The most popular idea – some form of crypsis or camouflage – was perhaps first expressed in Rudyard Kipling’s ‘Just So’ stories.  “With standing half in the shade and half out of it, and what with the slippery-slidy shadows of the trees falling on them, the Giraffe grew blotchy, and the Zebra grew stripy.”  But University of Bristol biologist Tim Caro, who’s written an entire book on the subject, dismisses this and 16 other hypotheses.  Sexual selection?  No, says Caro, because you expect sexual dimorphism (differences between the sexes) when sexual selection is operating (think peacock and peahen: flamboyant and drab).  No marked sexual dimorphism in zebra.

Caro comes to an unexpected conclusion.  (The epigraph at the beginning of his book comes from Sherlock Holmes: “When you have eliminated the impossible, whatever remains, however improbable, must be the truth”).  He thinks that zebra stripes evolved to reduce the impact of biting flies (which – think tsetse – are often disease-carrying in Africa).  Experiments indicate that flies are indeed averse to landing on surfaces with contrasting color patterns.  Here, from a 2020 paper, is data on the flight trajectories of flies approaching horses clad in “coats” with different patterns.  The red lines on the left represent individual fly’s trajectories.  On the right, the gray line is for a horse coat in a plain, solid color; the red, blue, and green ones for various striped or checkered coat patterns.  Flies approaching the plain, solid color are around twice as likely to approach close enough for a landing relative to flies approaching the striped/checkered coats.

Overall, this suggests that the selective pressures driving zebra stripiness lie in the specifics of the biting flies’ visual systems.  Weirder and weirder.  And perhaps appropriate: Earth’s most surreal inhabitants are made that way by the quirks and limitations of dipteran vision.  Magritte would love it.   Stay tuned for further developments!

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Mountain Gorillas

Gorillas, our closest living relative after Chimpanzees, have a most recent common ancestor with humans about 10 million years ago.  Today, there are two recognized species, Eastern and Western Gorillas (Gorilla beringei and G. gorilla, respectively), which separated about 1.75 million years ago.  Mountain Gorillas (Gorilla beringei beringei) are a subspecies of the Eastern species.  Mountain Gorillas, which, when last censused a few year ago, numbered only 1,000 individuals or so, exist in two populations, one in Uganda’s Bwindi Impenetrable National Park, and the other  in the Virunga volcanic mountains of Central/East Africa.  I visited one of the latter populations, in Rwanda’s Five Volcanoes National Park.

Mountain Gorillas were famously studied first by George Schaller and then by Dian Fossey.  Together, they established the baseline for long term primatological studies of the species.  Critically, they demystified Gorillas: gone was the belligerent King Kong image; instead, they are Gentle Giants, King of Vegetarians.  Fossey went on from Gorilla science to Gorilla advocacy, championing her Gorillas in an intensely personal way.  Her work was supported by National Geographic: a true synergism with the magazine gaining great copy and remarkable images of Fossey in the field with her Gorillas, and Fossey gaining research support and a prominent mouthpiece for her conservation message.  These conservation priorities – complete with aggressive anti-poaching measures —  were prompted in part by the death in 1978 at the hands of poachers of a male gorilla, Digit, a particular favorite of hers.  She was murdered at her field site in the Virungas in 1985, possibly by those she had antagonized in her campaign against poaching.  She was buried there, beside Digit.  Fossey was a divisive figure for sure, but she did a great deal of important pioneering science and is probably responsible for the conservation success story that the Mountain Gorillas represent today.

Fossey’s 1988 book, Gorillas in the Mist, remains a classic of field biology.  The movie of her life, with the same title, starring Sigourney Weaver, came out just three years after her death.  Recommended: plenty of the film was made on location in the spectacular forests of the Virungas.

Part of that conservation strategy is to bring money in via eco-tourism.  I was impressed by how well this is organized in Rwanda.  Many groups of Gorillas have been habituated to humans, a process first started by Fossey.  Primatologists need to habituate the animals to their presence if they are to study them; and habituation is necessary too if tourists are to be able to get close to the Gorillas.

The Five Volcanoes National Park permits groups of no more than eight tourists, appropriately accompanied by guides and trackers, to visit specified groups of Gorillas.  Each encounter lasts no longer than one hour.  I visited the Mutobo group close to Fossey’s Karisoke research camp.  The team guiding my group was enterprising and patient – it’s not easy going through the dense vegetation – and passionately concerned about the well being of their charges.  Masks on.  The last thing we wanted to do was to transmit a human disease to our close relatives.

I was surprised how powerful and affecting it was to spend an hour in the company of Mutobo’s group: we encountered the mighty, massive silver back, a couple of reproductive females, and several hyper-active juveniles.  The humanness of the scene was unmistakable: an excited and active baby trying to induce Mum or Dad to play, when they – we’ve all been there – were much keener on taking a nice early afternoon nap.

An up-close-&-personal encounter with our Great Ape relatives is a sobering experience: we are different, for sure, but also disconcertingly similar in so many ways.  Traditionally, we tell the story of Darwin’s ‘Eureka!’ moment in the Galapagos Islands when he noted the adaptive differences among the bills of the birds – Darwin’s finches – and started to think about a process, evolution, that could account for the planet’s biological diversity. In fact, Darwin realized the significance of the Galapagos finches only in retrospect.  An unsung key moment of the Darwin story was, I believe, more important in his journey of scientific discovery.  Shortly after returning from the Beagle voyage, he spent time, in the London Zoological Gardens, with the first living Great Ape ever brought to London, a juvenile female Orang (another Great Ape species that is slightly more distantly related to us than Gorillas) called Jenny.  We know from his notebooks that Darwin was flabbergasted by the humanness of this animal.  We are no different from Darwin on this: a close encounter with great apes is sure to reinforce the sense that we humans are an embedded part of nature, rather than somehow disconnected from it.  My Darwin-meets-Jenny experience took place in the Virungas.  A special privilege.  And I was pleased too to be able to visit the site of Fossey’s camp and to pay my respects to her final resting place, beside her beloved Digit.

The plaque marking Fossey’s grave includes her local name, Nyiramachabelli, meaning ‘Woman who lives alone on the mountain’