Rain brings changes to the African savanna. As storm clouds near, even the smells change. The temperature flutters, falls; the stuttering, buzzing and sawing of insects takes on a different pitch; then a hush, before the pittering of raindrops splashes dust from the baked ground. The pittering turns to a pattering, then to a deluge, soaking and streaming. It may stop almost as soon as it starts or continue for hours.

Close observation of a leopardess enjoying her daytime relaxation

The rain cloud shadows pass, the ground steams, the grass glistens, brilliant colors return and life moves on.

I was tucked away among a stand of trees at the north end of Chief's Island in the Okavango Delta. Gently undulating savanna stretched in all directions. Lines of trees marked wet-season water courses; open grasslands, flood plains at other times of year, were dotted with game.

A rainstorm moving quickly through in the late afternoon drove another cloud up into the sky: Thousands of dragonflies suddenly took to the wind. I had been so focused on other things that I hadn't noticed them at all, but suddenly with that characteristic dry rustling that marks the dragonfly's flight they filled the air, and streamed away over the trees. They, it seemed, preferred to stay ahead of the rain and remain dry if possible.

Perched in an open-top Land Rover, I put on a poncho and resigned myself to a soaking. I had no intention of moving on, for just a few meters from me lay a magnificent, dapple-coated leopardess. I had been following her and another leopardess for much of the day, watching her behavior, enjoying her proximity and marveling at her fluid grace and movement.

An hour or so before she had been lolling on a tree limb, relaxed in her siesta, though her high perch on a broad branch in an acacia tree was not my idea of an easy day bed. She seemed comfortable, though, her legs dangling on either side of the branch, her long tail hanging, its tip twitching occasionally. Periodically, she opened an eye, surveyed the scenery, then dozed again.

Unfortunately for her, she was discovered. Red-billed francolins are the noisy sentinels of Okavango, shouting their distrust, dislike and alarm from the trees, and a pair of these chicken-size birds moving through the open woodland had spotted her. They climbed through the trees closer to her, shouting the francolin equivalent of "Beware, beware, there's a leopard!"

Their harsh calls were loud enough to wake the dead, and, seemingly unable to bear them any longer, she roused, languorously rose on her branch, stretched powerful limbs taut and yawned, fearsome teeth bared. At first she tried to shock the francolins into fleeing, but after several attempts to chase them through the branches had failed, she seemed to decide that she was not onto a winner. With the astonishing power that a leopard displays when vertical, she climbed easily down the trunk of the tree and set off through the bush.

For a while the francolins continued shrieking, but as she passed out of range they lost interest and peace returned.

In absolute silence she moved through the bush, blending with the shadows, easing through gaps between bushes that hadn't seemed to be there until she walked through them. Where she went I could not follow, so it was a game of hide and seek through the bush. I caught glimpses -- a tail here, a patterned flank there -- and guessed her direction.

Finally she settled again, this time in a quiet grassy corner in the open, between bushes. Now I could admire her at close quarters. Though relaxed, she was lithe, fit and as ready for action as a leotard-clad aerobics instructor.

At such close range I could stare into her eyes. She stared back.

It is one thing to appreciate the limpid depths of an animal's eyes in the zoo, but here there were no bars, no cages and no protection except habit. Her eyes were those of a powerful and calculating predator. I had no doubt that had I been on foot the message her eyes gave me would have read "easy meat!"

As she settled further into her rest, turning her head, I was able to confirm that she was definitely a different individual from the one I had followed that morning. That cat had had a small but bloody nick in the pinnae of her left ear. In all other respects she too had been a fine specimen, intent on patrolling her territory.

Leopards are survivors. Wide-ranging, they are still common across much of Africa and Asia, yet their generally nocturnal habits mean they are often overlooked. They are the most widespread large cat in India, for example, yet many people are unaware of their presence -- unless, perhaps, they hear the brief screams of a dog falling prey to one in their village.

Solitary and secretive, they blend in. Resting by day amid bush or woodland where they are camouflaged, they venture out at night on short dashing forays for food. Where lions rely on the massed strength of the pride and cheetahs are swift in pursuit of gazelle, leopards are leapers and ambushers. Keep your eyes on the trees if you are walking in leopard country! After a successful ambush they reveal their phenomenal strength, dragging animals weighing as much as themselves high into the branches of a tree.

They each patrol a territory, and in the morning I had been fascinated to watch the female doing just that in daylight. Pacing through her range she sniffed at trees, occasionally turned, backed up to one and sprayed urine onto the bark before moving on. Here and there she left other marks as she reached up, stretched and scratched into the bark the unmistakable signs and scents of her territorial possession.

A few nights before, I was wakened abruptly at 11 p.m. by the male leopard's method of confirming his control. His astonishingly loud call seemed to come from just outside my cabin; later I learned he had walked straight through the middle of camp. The sound is like an immense cross-cut saw cutting through a rough log. A powerfully primeval sound from the African night.

Finding one leopard in its large territory is like finding the proverbial needle in the haystack, and I had been fortunate enough to watch two in one day. I was aware of my good fortune as I settled down to wait nearby.

The leopardess rested. It is hard not to anthropomorphize about such a magnificent creature, so finely tuned by evolution to its environment. No concerns about commitments, deadlines or tax bills furrowed her brow. The more simple drives of survival, procreation and nurturing would have been dominant; stress factors for her would be the intrusion of another leopard into her territory, and concerns for the safety of her young, if she had one hidden nearby.

She seemed aloof, unconcerned and unimpressed by a human. She was superior, there in the African bush. With the fractious francolin alarm now stilled, it seemed nothing could disturb her. She didn't bat an eyelid when the cloud of dragonflies distracted me. Rumbles of thunder and flashes of lightening were of no concern as the storm rolled ever closer. She shrugged off the raindrops as if they were nothing.

But when the loudest clap of thunder I have ever heard erupted from the slate-colored sky overhead, she nearly jumped out of her skin.

It is impossible to describe the way surprise registers itself on a leopard's face, but when it seemed that the whole sky had cracked at once, she had leaped in fright.

I had to smile. Perhaps she wasn't quite so invincible after all.