They were just going about their daily business: the elephants strolling, the hyena mooching, and the pair of thirsty pandas taking a refreshing drink. Then... gotcha! With the click of a hi-tech shutter and perhaps a blinding flash, a moment from their hidden existence was captured for posterity.
In recent decades, scientists have come to rely heavily on motion-sensitive cameras to conduct research into animal populations and behaviour. The tiny automated devices, which can be left in remote areas for weeks at a time, are triggered by sudden changes in temperature.
Until now, the photographs that they produce have largely been kept below the radar: made public only via the publication of scientific research projects. Though they are often pretty and occasionally fascinating, the primary purpose of the images has been to inform professional ecologists.
That all changed yesterday, when the Smithsonian released a vast database of more than 202,000 "candid camera" shots, from seven major projects around the world, via its website. The collection is available for viewing to the public via the newly launched "Smithsonian Wild" website.
While many photos are relatively mundane, a few capture moments of high drama: one shows an ocelot creeping up behind an armadillo, ready to pounce.
Each shot is published with a record of the exact location and time at which it was taken, allowing scientists to use it to draw educated conclusions about the spread of animals across the globe in a way their forefathers could only dream of. "In the old days, we used to spend hours in the wilderness debating what animal might have left a piece of faeces, or a footprint, on some remote path," says the project's curator, wildlife ecologist Dr William McShea. "Well now we don't need to do that any more, because these cameras have come along which take pictures that provide proof."
The creators of the online database are already sorting through another 500,000 images held by the Smithsonian. They hope the site will eventually become the accepted home for hidden camera shots taken on animal research projects around the world.
"Hidden camera pictures provide a record, much like those old cabinets you pull out in museums, which have musty old stuffed squirrels in them, plus a bit of paper saying when and where it was killed," says Dr McShea. "They are incredibly valuable."
The technology for creating cameras, motion sensors and batteries small enough to be taken to remote areas has only existed for just over a decade. Its development was largely financed by the American field-sports industry, since the devices are useful tools for managing game populations.
Some animals, most notably tapirs, peccaries, agoutis and paca are so comfortable with the notion of being on camera that they will remain around them long enough to provide entire sequences of photographs.
Others react like a celebrity caught by paparazzi. In Africa and Asia, the cameras have to be housed in robust boxes to prevent them being used as footballs by elephants. Golden monkeys in China have been pictured coming down to the ground and urinating on the cameras.
Every ecologist has their favourite photo, of course. McShea's most treasured ones are of Takin, which are found in high alpine areas of China's panda reserves. (One is shown in the furthest picture to the left of the second row here.) "In the past, the only time I got to see them was when their butts were disappearing over the brow of a hill," he says. "Now I see them in a way that makes their personality come across. They are huge goats who look like the sort of creatures that only their mother could love."