Several thousand sentinels stand alert in the shadows across our tiger lands. Secured with lengths of cord to the salty trunks of mangroves in the Sunderbans, corky rhododendrons in the lower Himalaya and prickly Prosopis in the Aravalis, these camera traps maintain a vigil over India’s tiger habitats. Ever watchful, their shutters only blink when an animal approaches, or vegetation stirs in the wind, snapping images. They capture all motion in the forest: a resplendent dancing peacock, a tiger flaming orange in afternoon light, a furtive fawn grazing, its mother out of sight, a bear shuffling by bearing babies on her back, a summer squall twirling leaves in a spiral. As the shadows lengthen, two muddy boars spar, bicycle borne humans – double sawari, a lingering stork, an ambling pangolin and two curious macaques all make appearance. Aided by a flash, the cameras see into the dark as well. The night yields images of six gargantuan elephant feet and two trunks that fill the frame, a startled porcupine, and a pair of jackals noses held to the ground.

As India counts its tigers one more time, under the aegis of the National Tiger Conservation Authority aided by its partner organizations, time-stamped and geo-tagged images from camera traps lead us to layers of vital information about this elusive and endangered feline. At first glance, they tell us where tigers occur and where they do not. Over multiple years, together with other information on prey and habitats, these data are analysed to ascertain where tiger distribution is expanding or shrinking, both within and beyond Protected Areas. Because each tiger can be identified by its unique stripes, we are also able to build individual profiles. Sophisticated statistical algorithms allow us to ascertain how many tigers are likely to have eluded the webs of camera traps, and yield estimates population size. If a tiger isn’t detected or photographed by the camera traps, it could mean either true absence of the big cat in the area or simply the fact that it went undetected. Yet, over time these data points can lead us to some reliable insights about population trends.

Camera trap data proffer many other insights about both individual tigers and populations, which are vital for the species conservation.  They inform us about the territorial boundaries of individuals that are guarded from rivals. The birth of cubs and the dispersal of young individuals are recorded. We learn of territorial infighting when we come upon images of injured animals or of those displaced of their territories. These images provide glimpses into the interactions and diurnal rhythms of tigers and their prey, and of their influence on smaller competitors like leopards, which often avoid them. Further, we learn of the predilections of individuals to frequently revisit certain areas while avoiding others.

There are also important lessons to be learned about the tigers’ behavioural response to humans that enter their habitats. For example, in areas where humans extensively use tiger habitats, the latter maintain temporal separation.  Photographic data has led to other revelations: multiple generations of tigers can sometimes inhabit farmlands and plantations away from forests. In their quest for mates or territories, the individuals can cover hundreds of kilometres following drainage features through human habitats. Finally, when known tigers disappear from a population, we rue the loss and wonder whether they have immigrated or are dead. Sometimes we confirm mortality when the pelage patterns on a skin or carcass recovered by enforcement agencies matches that of a known animal. Occasionally, a missing tiger is photo-captured in a distant habitat that it dispersed to.

Having once studied wild sheep and gazelles in the high Himalayas, where I followed these hardy beasts on foot - sometimes stalking them on all fours to get close - and then observing them for hours through a scope, I rued not being able to observe tigers as intimately or frequently. This is no longer a lament. As we have compiled more camera trap data over the years, I learned to my joy, that these image banks reveal a lot more than what meets the eye. It is no surprise that networks of camera traps are being used the world-over to document the status of biodiversity as wildlife habitats shrink or face increased anthropogenic pressure.

This brings us to the art and craft of deploying camera traps in the field. Fredrick Walter Champion, an officer in the imperial Forest Service in the early 1920s spent time in Landsdowne Forest Division in the Himalayan foothills, now in Uttarakhand. Champion had traded his gun for a camera, and was on mission was to photograph tigers and other wildlife. His equipment kit held a camera trap with magnesium flares that he deployed with significant success. In his 1927 memoir, In Tiger land with a Camera, he expounds that profound knowledge of the geography and tiger behaviour are needed to successfully apply ‘automatic photography’.

Champion passed away in 1970, just years before the establishment of Project Tiger in India. Proactive conservation measures since have enabled the survival of the species he so admired in Lansdowne Forest Division. In fact, every few years when India’s tigers are counted, this population, like many others, is exposed to hundreds of camera traps over the span of a month or two. While camera technology has greatly evolved, the craft of deploying camera traps over large, rugged areas such as this continue to test the field skills and mettle of forest guards and biologists alike. 

A few months ago, two young colleagues accompanied by a local buffalo herder set forth on a day-long mission to check a few pairs of camera traps in the remote reaches of this very division. The early monsoon heat is oppressive. The trio wound their way along a narrow hill track, in the footsteps tigers and a lone elephant. Fatigued, they finally arrived at a stream one bend away from the cameras and three growling tigers made an appearance! In the fraught, confused moments over which the quivering team contemplated their guarded retreat, a snarling tigress broke away and appeared on a muddy embankment, only a few arms’ lengths above. Saddam and Jyoti slipped into the stream in their attempt to back-off, and sat in the water, frozen in fear. Devavrat closed his eyes, swung a sickle before him and prayed fervently. When he opened his eyes seconds later, the tigress had landed only a few strides away, and mercifully walked off in the direction of her grown-up offspring. The team and I returned to this spot a few days later to retrieve the camera traps. Fresh pugmarks writ boldly in the mud bore testimony to the continued presence of this terrifying yet benevolent family. However, the two cameras secured to poles at the stream’s edge were missing. Alas, they had been swept away by an unseasonably powerful rain-fed torrent.