My discovery has gone viral on BBC Earth!
It’s official, with over 10 million hits on the Facebook clip alone, the story that I discovered and revealed to the team who filmed the BBC America TV series EDEN: UNTAMED PLANET (episode 4) has become a smash hit!
It all started innocently enough five years ago. I had been invited to accompany a research trip to a small, rarely visited island, and while the scientists were busy working on data collection, I was sitting high on a cliff edge, gazing out at the ocean below. That’s when I first spotted a group of Galapagos sea lions porpoising at full speed, approaching diagonally towards the place below where I sat. They were zigzagging slightly and at times diving deeper and reappearing in unison. I took a few shots thinking to myself, “Wow, these guys are really in a hurry to come home!”
At first sight, I had no idea I was about to make an extraordinary discovery about
Galapagos sea lion intelligence, planning and cooperation!
Indeed, somewhat to my right, there was a tiny cove with a golden sand beach where a small colony of sea lions rested with their pups. But the swimming sea lions were not headed that way, instead making a beeline directly towards the base of the 35m high cliff where I sat. Soon I also noticed that a dozen or so brown pelicans had appeared as if out of nowhere, launching off from their various cliff perches, and now converging towards the swimming sea lions.
It was obvious that the pelicans knew something that I didn’t!
Sea lions were jumping this way and that,
it all looked very confusing!
Suddenly the mob doubled back and was heading for the beach, with the pelicans flying ahead — what next?
I began to realise that something incredible was happening, that I was witnessing an event never seen before, but I still had no clue what this might be.
It all looked like complete confusion, as the fast-moving sea lions fanned out and dove deep, while the pelicans circled low over the water.
The next minute, the panorama had completely changed: Now all the sea lions, as well as the pelicans flying slightly ahead of them, were heading hell-for-leather towards the beach.
Clearly there was some sort of intensive hunt going on!
As the hunters approached the shore, the pace became frenetic!
When they reached the sandy shallows, suddenly the object of their chase was revealed. A tightly-packed, super-speedy school of blue-green fish became visible against the light sand bottom — later identified as amberside scad, though sometimes referred to by the more generic name of jacks.
I couldn’t believe my eyes! Using a pincer movement to prevent their prey escaping, and increasing their speed to the max, the intelligent hunters drove the entire school directly onto the beach, even washing some fish high and dry, aided by the mini-tsunami wave that their tightly packed rank produced as they too launched themselves ashore.
Equally amazing to me was that the pelicans were already wise to the sea lions’ manoeuvres, and had landed on the beach just ahead of their arrival, big scooping beaks at the ready for when the fish leapt ashore. This clearly meant that this wasn’t a random or isolated event, but rather a tried and tested tactic.
The ensuing feeding frenzy was a chaotic writhing free-for-all amidst a confusion of whitewater and sand, with wings flailing, sea lions leaping over each other, fish flapping, and tug-o-wars between and among birds and mammals.
What’s more, in 28 seconds flat (as later revealed by the time-stamps on my photos) the entire scene was over.
The hunters dispersed back out to sea and the pelicans returned to their favourite perches. Even the resident sea lions resting on the beach, briefly roused from their slumber by the nearby commotion, had barely had time to lift their heads uncomprehendingly before peace returned as if nothing had ever happened.
Pelicans were well aware of the sea lions’ premeditated drive,
which convinced me that this was a tried and tested tactic repeated over time!
Although much faster swimmers than sea lions, very few scads managed to
escape the carefully calculated moves of their enemies!
For less than half a minute, chaos and competition reign, until every last fish is consumed!
When the full realization of what I had just observed began to sink in, I felt totally stunned, dumbfounded! Nobody had ever reported such behaviour in the past.
I had just made a brand-new discovery demonstrating the intelligence and cunning of one of the top predators in Galapagos — our endemic sea lion — which involved planning and cooperation to succeed in corralling fish that can swim much faster than they do.
For a brief few seconds, there’s a feast for everyone!
Realizing this, I immediately shared my news with a cameraman friend who often works on major nature documentaries. While he spent four years searching for an appropriate outlet for my discovery in the filming industry, I returned to the island several more times to find out more details of the behaviour. Eventually, almost five years after my initial discovery, I agreed to collaborate with a BBC production called EDENS. Filmed over nearly five weeks, the resulting episode is both stunning and endearing. It was released by BBC America in September 2021, and will also be distributed throughout China and elsewhere. That’s why, if you watch the Galapagos episode of EDEN: Untamed Planet, and see the credits, you’ll see my name as ‘Consultant’, ha-ha!
Another hunt is about to make landfall.
The time-stamps on the four images below show the speed with which the hunt takes place!
Check out the scene that the BBC team was
able to film with my guidance here:
Meanwhile, through a total of 284 hours of observation spread over 31 days in different seasons, I’ve been able to document a full 40 hunts, of which 32 were successful.
By systematically extracting detailed data from the analysis of over 2,400 photos taken from various vantage points, and, crucially, with the most generous help of the doyen of Galapagos sea lion research, Dr. Fritz Trillmich of Bielefeld University in Germany, I am proud to have also been able to publish my very first scientific paper as first author:
Cooperation and opportunism in Galapagos sea lion hunting for shoaling fish
ECOLOGY & EVOLUTION (July 2021)
by Tui De Roy, Eduardo R. Espinosa, Fritz Trillmich Read here.
Attracted by the commotion,
even the sharks arrived too late to cash in on the feast!
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