Seeing a special bird can take enormous effort, as I discovered recently on a quest in the jungles of Guyana. As we headed along a narrow river towards our destination, we had to cope with heat and humidity and navigate huge rocks and fallen logs. All this just to see a baby bird.

I say baby, but harpy eagles – named after mythical ancient Greek spirits with a raptor’s body and a woman’s head – are easily the biggest bird of prey in the Americas, and one of the largest in the world.

I had always wanted to see one but because they only breed every two or three years our chances were far from certain. Fortunately, soon after we arrived the youngster materialised seemingly out of nowhere, staring balefully across the river towards us from his nesting tree.

Roughly 18 months old, and almost 4ft (1.2 metres) tall, his appearance was quite bizarre: pale grey, his white head adorned with plumes like a court jester’s hat. He called plaintively to his parents somewhere in the surrounding forest, begging them to bring back food.

We stood and watched for some time, hoping one of the adults might return, but despite panicking calls from a nearby troop of howler monkeys, they presumably failed to make a kill. We left the young harpy still waiting for his dinner, those haunting calls echoing long into the distance as we headed slowly home.