Human activity has been blamed for the plummet in numbers, as the United States reports dwindling populations of bumblebees and polar bears - and one of the world's biggest decreases in sealife.Our ever-growing need for land and resources, coupled with hunting and poaching, has halved the number of wild animals in world in just 40 years, according to a shocking report.The Living Planet Report by WWF and the Zoological Society of London has found that wildlife populations around the globe have declined by 52 per cent on average since 1970.The authors compiled data on 10,380 animal populations, including 3,038 different species, as an index to judge how global wildlife is faring as a whole.In the US, fish have decreased by 83 per cent between 1970 and 2010 - the second largest drop after Latin America which lost 86 per cent in the same period.American amphibians have also struggled in the modern world, with an overall decline of 73 per cent recorded, while the total number of reptiles dropped by 48 per cent nationwide. The great white shark is one of the United States' worst-affected species, having lost around 50 per cent of its population in just 20 years, largely due to oil spills in the ocean. (dailymail.co.uk)Bakudaily.Az