They have painted their antlers in fluorescent colors, hung reflectors round their necks and even used movable traffic signs. But little has been successful in stopping the 4,000 reindeer deaths on Finland’s roads every year. Now, reindeer herders are turning to technology by launching a warning app. They have issued lorry drivers with 1,000 free interactive mobile gadgets which warn them of nearby reindeer and allow them to register their own sightings with a tap on the screen. If successful, the app will be available for download on all smart phones later this year.