The male frigate bird inflates a huge red pouch beneath its beak while cawing to captivate female mates. On the Galápagos islands, it’s the basis of a mating ritual; on Tinder, it might get you banned.
But as we learned form the first of this tremendously informative six part series, Equator, about the equatorial region’s flora and fauna (Sky Nature), sexy inflatable neck pouches aren’t all that the frigate bird has got to offer. Rather, what’s most striking is the way it has hitched its evolutionary wagon to the booby bird, even changing its breeding patterns to synchronise with the boobies and shadowing them through the Pacific skies before pouncing and seizing their dinner. In human terms, it’s like a Deliveroo driver being stalked by a rival with a clever, if illegal, business model.
We saw a booby plunge head first into the sea to seize a fish. But as it rose skywards with its catch, a frigate bird – a kind of airborne pirate – eyed it narrowly and then swooped. The frigate bird is poor at catching fish, but superb at stealing another bird’s catch. It seized the tail of the booby midair and shook it until the booby released the fish from its gullet. The frigate bird then swooped to catch the falling fish and flew off to feast on it.
Such niche evolutionary moves are not unusual here, as we will see in a moment when we consider the incredible shrinking marine iguana. Or consider the butterfly fish: in the Palmyra atoll, also along the equator, they feed on coral reefs, while in the waters of the eastern Galápagos they become cleaner fish, dining on bigger fishes’ parasites.
The frigates’ midair thieving must be distressing to boobies because life on the Galápagos is otherwise chill, with no natural land predators. The Galápagos cormorant has gone a stage further in lowering its evolutionary guard: over millennia it has stopped using its wings for flying.
The makers of Equator carved their own niche in a TV environment where it’s adapt or die. Like the bump-headed parrot fish, which spends its life eating coral with a parrot-like beak, excreting sand and head-butting sexual rivals at mating time. Or the giant manta ray, which is three metres wide, most of it mouth, down which it sucks zooplankton as it rises. Similarly, the programme makers conferred on themselves an evolutionary advantage by not doing what everybody else in natural history docs does. How delightful that they dispensed, in particular, with some preening presenter who, after racking up air miles to get on location, lectures us on environmental damage as they interpose themselves between viewers and what the programme is notionally on about. How nice that here humans aren’t the stars of the show.
Equator – though by no means as visually sumptuous as Blue Planet – was probably more informative than much of David Attenborough’s hallowed oeuvre. Well-judged graphics and a literate script helped me understand for the first time how the spin of the sun and the Earth combine to produce trade winds, and that the resultant oceanic currents and cross-currents create microclimates such as those around the Galápagos.
However, the best thing about the documentary was its rebuke to human hubris. Consider the Galápagos’s marine iguana. Have you ever shrunk yourself by a quarter to give yourself a greater chance of survival than your peers in cooler temperatures? Have you lowered your heart rate and body temperature by more than 10C so you can dive to the seabed and graze on algae for two hours without freezing to death, in waters 15 degrees colder than the surface? Have you then struggled to return to the surface, or even digest said algae because your muscles are so cold? And so have you spread yourself out on a rock, suppressed hunger pangs and waited for hours for the equatorial sun to warm you so that you can digest the food that’s been sitting heavy in your stomach?
If you answered yes to any of the above, strap yourself in for a lie detector test. In truth, like me, you haven’t got what it takes to survive in extremis.
• This article was amended on 10 August 2020 to remove a reference to the “giant cormorant”; this bird’s correct name is the Galápagos or flightless cormorant.