If there’s one thing I like after a hard day’s saving the rainforest it’s a nice cold beer. And it’s all the better for the evening cabaret: the crepuscular nectar-dance as the day shift clocks off and the night shift clocks on. I was out in Brazil last week, travelling with the World Land Trust, which was seeking to buy up and safeguard a few more chunks of rainforest.

And after a day of travelling, sometimes by Land Rover, sometimes on foot, sometimes on horseback, to inspect the forest at the Reserva Ecologica de Guapi Assu and a good few more bits around it that might one day be available for purchase, we would regroup back at the lodge to talk forest and drink beer.

As we did so, the last hummingbirds of the day would take their last frenzied sips of sugar-water – pseudo-nectar – from the feeders dotted all around the garden. See them: a fizz of sound and a blur of wings, everything in motion save the perfect stillness of the beak.

Astonishing things: defiant, apparently, of the basic laws of physics. One of them, a swallowtailed hummingbird, was insane with territorial lust, and launched himself violently at any other bird that dared to sup– a full-time job.

But as the hummingbirds finally gave up their beautiful gavotte of greed, their place was taken by other flying nectar sippers: visiting the feeders, taking turns with exaggerated good manners after the hummingbird battles, one minute sip following another.

Not birds: bats. Nectar-feeding bats, that sip from night-blossoming plants: pollinators and vital parts of the rainforest ecology. Bats make up half the species of rainforest mammals, and worldwide they range from the six-foot wing-spanned flying foxes to the ridiculously little bumblebee bats. All the mysteries of rainforest and biodiversity are to be found in the subtle but essential differences between bat and bat.

And here they sipped and vanished into the shadows, an endless and apparently perfectly peaceful queue. A beer with the hummingbirds, followed by a second beer with the bats: see how perfectly nature can order things when given half a chance.

— We travelled farther south, to look at some more surviving bits of Atlantic rainforest that may be available for purchase and salvation. As we did so, we paid a visit to Tingui Park in the city of Curitiba, because we had to see for ourselves a city park that had capybara instead of ducks.

Not a captive population: real wild free-living capybara that sat there like megalomaniacal guinea-pigs – they are the world’s largest rodents and can reach 40kg – as Curitiba’s Saturday afternoon people strolled, pushed prams, flew kites, walked dogs and played with children.

The capybara sat there, some on islands in the lakes, others boldly at the lakeside, perfectly comfortable in this surreal situation. Two horrid little girls tried to herd them in to the water with stamps and clapping: the capybara barked crossly and moved a little closer to the edge. When the girls started spitting, they changed tactic and advanced. They are too daft-looking to be menacing, but it was enough to give them privacy.

Tingui Park is a rough-and-ready Garden of Eden: an effective and slightly uneasy experiment in coexistence. If humans could coexist a bit better with rainforest, humans themselves would be a lot better off.

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