Kaitlin Barham, PhD candidate at the University of Queensland

It is my last day of fieldwork in 2021, a handful of hours left in this remote North Queensland paradise, and we’re hunting for a ghost. The team have taken to calling him Baba Yaga because John Wick is the movie of choice this year (there are only so many DVDs we can take with us, this far from anywhere). Something about the name sends chills down my spine. I’ve heard stories about him: a sense of something behind you, watching, but only ripples when you turn around. He’s cunning, and he’s old.

I’ve spent years becoming familiar with estuarine crocodiles through their data. I could show you JK’s incredible egg-laying migrations strung out across a map, or the tragic end to Jeurgen’s reign as king of the river, told through years of declining health records. But it’s one thing to study crocodiles from the comfortable safety of my office, and quite another to meet them in their world.

The river that marks our study site appears calm, a slash of green through the dusty scrub forest around us. But as soon as we launch the boats, things shift. It never feels completely safe on the water, and with the situation liable to change at the drop of a hat, it’s never completely in my control either. I don’t really want it to be either of those things because it’s beautiful and wild too. Still, there’s a little thrill of fear mixed into the wonder when you see a croc slide on the bank and realise it’s bigger than your boat.

We arrive at the site where we’ve laid our trap for the ghost and find it eerily quiet. The air out here is always alive with insects and birdsong but right now the only thing I can hear is water lapping at the riverbank. The silence vibrates in my ears, and I remember learning that horror movies use infrasound (sounds below our range of hearing) to build a sense of unease. Outside of television, infrasound is produced by forces of nature – storms and earthquakes, or huge animals like elephants. Crocodiles can produce it too, if they’re large enough.

I’m rooted to the spot, but one of the more experienced team members rushes past me. He checks the trap and examines the ground, and with something like awe in his voice he tells us that our ghost was here, and recently. He shows us the flattened grass all around the trap, and the footprints spaced so widely that he practically has to do the splits to match them. The lead-in bait is missing, which means Baba Yaga stuck his head in the trap, enjoyed an easy meal, then left without triggering the mechanism.

Although there’s no sound of splashing, ripples spread from a spot near the bank. We watch with bated breath, and somewhere under the surface, the ghost watches us back. I wonder what he thinks of us, in all his prehistoric wisdom, as we swarm around his footprints and reset the bait in the hopes that we’ll see him up close tomorrow.

In the end, we don’t see him again, not in 2021. Once I leave the reserve, there are only a few days left until the traps are taken down for the year, and he doesn’t show himself even once.

But that’s not the end of the story.

One year on, and we’re once again on the reserve. Every croc we add to the study is a cause for celebration, but no croc is anticipated more than our ghost. So great is the excitement when he’s caught – and finally, after all this time, it really is him – that it only takes a wordless confirmation for the entire campsite to erupt into cheers, then frenetic movement as we prepare for the hard work to come.

The ghost is enormous, 4.5 m of muscle and rage, but he’s soon safely released into the river with a satellite tracker fastened to his scales. He’s called Maximus (Gladiator is the new John Wick), and the name fits like a glove. He’s absolutely stunning. Astonishingly, his scales have been marked in a way that indicates he’s been caught before, though not by us. We’re able to trace this unique id code to a 22cm juvenile caught in 1986.

Our ghost is only 37 years old.

The data obtained from Maximus will be extremely important to our study. As a dominant male, his movements and interactions with other individuals are integral to their social structure. And, as a large individual of known age, Maximus will help us understand how crocodiles grow over time.

While I look forward to analysing the data we get from Maximus from the safety of my office, I won’t soon forget the experience of meeting a legend face-to-face. Crocodiles are so very deserving of our awe, and our respect.