The birds are renowned for their sophisticated tool - using ability , but until now , observing them in their natural habitat has proven difficult . But specially designed " crow - cams " fitted to the birds ' tails have shed light on the creatures , recording some tool - use never seen before . The research is reported in the journal Science . New Caledonian crows ( Corvus moneduloides ) are found on the South Pacific island of New Caledonia . They can use their bills to whittle twigs and leaves into bug - grabbing implements ; some believe their tool - use is so advanced that it rivals that of some primates . Why not just stick a camera to a crow , hitch a ride with it , and get a crow ' s eye view of what is going on ? Christian Rutz But while these clever crows have been extensively studied in captivity , looking at their natural behaviour in the wild is tricky . Christian Rutz , lead author of the paper from the Department of Zoology at the University of Oxford , UK , said : " These birds are notoriously difficult to study in the wild . " They are very sensitive to human disturbance and the terrain in New Caledonia is very mountainous and forested , so it is difficult to follow the birds . " So the team came up with another approach . " Why not just stick a camera to a crow , hitch a ride with it , and get a crow ' s - eye view of what is going on ? " Dr Rutz said . New toolsRecent advances in mobile phone technology enabled the researchers to construct a camera that was small enough to attach to a crow ' s tail without impairing its movements . They attached the 14 g ( 0 . 5 oz ) units - which also contained a radio tag to transmit location coordinates - to the tail feathers of 18 New Caledonian crows . The video camera weighs only 14 gThe footage , broadcasted to the researchers ' custom - built receivers , provided the team with a unique insight into the crows ' behaviour - including some that had never been seen before . Dr Rutz told the BBC News website : " Before , we thought the crows targeted their tool use at fallen dead trees where they probe for grubs ; but now we have observed them using tools on the ground - and that has never been seen before . " We also filmed them doing this using a new type of tool , which was very surprising . We found them using grass stems - and that is interesting because these stems have very different physical properties from the sticks and leaves that we knew they use . " They are using the grass stems on the forest floor , probing the leaf litter , possibly fishing for ants . " Big juicy grubsThe team is using its video footage to investigate why New Caledonian crows might have evolved their tool - using abilities . This species of crow is the only non - primate animal known to create and use new tools . Dr Rutz said : " What were the ecological circumstances on this one particular island in the South Pacific that could have fostered the evolution of this behaviour ? " This technology could really change the way we study wild birds Christian RutzOne idea , he said , was that the behaviour may have evolved in response to food shortages . " When we compared situations when the crows did and didn ' t use tools , we found two pieces of supporting evidence for this , " Dr Rutz said . " Firstly , the prey encounter rate was surprisingly small : for one hour of ground foraging a crow would only pick up eight tiny morsels of food - a blackbird in a garden would be taking up that many items a minute . That shows maybe foraging without tools is indeed challenging in this habitat . " Secondly , when you compare the size of the food items they get with and without tools - when they don ' t use tools , the food items are very , very small indeed compared with the food items they extract with the tools . This again suggests maybe they need to use tools to gain access to this rich hidden food resource . " The team says its video tracking technique could be used to study other wild birds that are shy or live in inaccessible habitats . Dr Rutz added : " This technology could really change the way we study wild birds . "