You’d think that the more time you spend looking at wildlife, and especially, the more time you spend watching wildlife in the same place, the sooner you’d reach capacity. Seen everything, done everything, watched the place dry. But of course, it’s the complete opposite: the more you observe the ordinary, the more capable you become of noticing the exceptional.

Black-headed herons are pretty much of a size with the grey herons we see in England. You routinely find both species in the Luangwa Valley in Zambia, a place I’ve been many times. The blackheads are more likely to be found away from water, and in large numbers.

Tall birds, standing four feet tall. And yet here was one with a snake in its beak: and the snake reached all the way to the ground. It was an astonishingly ambitious catch for the bird, especially when the snake turned out to be a black-necked spitting cobra, a venomous snake that can spit venom a couple of yards and more to blind its would-be attacker.

The snake was still alive. It kept changing shape: concertinaing itself up in zigzags, falling straight again and then writhing to get free. As a general principle, the bird held the snake crosswise, high in the beak at the strongest part of the grip. Mostly the snake’s head was protruding three or four inches only.

But from this basic position bird and snake changed positions again and again. The bird repeatedly banged the snake’s head on the ground and tried to crack the snake’s entire body-length like a whip. It was a protracted business: the snake wasn’t keen on dying and knew that it still had a chance, if a small one. Eventually the heron had the snake more or less subdued; and then it was able to crush the cobra’s skull between the mandibles of its beak.

That seemed to leave the hardest problem till last: how to eat the damn thing. The heron took its time: you want to get this just right. Eventually the snake was manoeuvred until it was precisely headfirst, so the scales of the snake’s skin were lined up down the throat, so they would aid rather than inhibit the next stage — the long impossible sword-swallower’s swallow.

Inch by inch, clap by clap of the great bill, shake by shake of the implacable black head, the snake made his last journey: a posthumous slither down the heron’s throat. Not everyone can swallow a meal as tall as himself. Finally, with four inches of tail still protruding, the heron relaxed. Why not? That day’s work was surely now complete.

I looked him up in the great bird-book, Roberts’ Birds of Southern Africa. It said that black-headed herons will take “small reptiles”. Smaller than a Luangwa croc, I suppose, but not much…

· I was co-leading the Sacred Combe Safari with Chris Breen from www.wildlifeworldwide.com

http://www.wildlifeworldwide.com/group-tours/sacred-combe-safari