[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"question:1498:en-US":3},{"metadata":4,"sys":15,"fields":35},{"tags":5,"concepts":14},[6,11],{"sys":7},{"type":8,"linkType":9,"id":10},"Link","Tag","global",{"sys":12},{"type":8,"linkType":9,"id":13},"land",[],{"space":16,"id":20,"type":21,"createdAt":22,"updatedAt":23,"environment":24,"publishedVersion":28,"revision":29,"contentType":30,"locale":34},{"sys":17},{"type":8,"linkType":18,"id":19},"Space","ghhpjogyw4x7","1rcEMoapGFzzo1OMyXz8Wr","Entry","2022-09-27T13:50:23.086Z","2025-06-27T21:47:15.337Z",{"sys":25},{"id":26,"type":8,"linkType":27},"master","Environment",112,30,{"sys":31},{"type":8,"linkType":32,"id":33},"ContentType","question","en-US",{"isHidden":36,"globalId":37,"answers":38,"answersAsImages":36,"wrongPercentage":96,"name":97,"questionText":98,"statistics":99,"veryWrongStatistics":101,"correctSentence":103,"youWereWrong":104,"youWereRight":105,"dataSourceShortText":106,"dataSourceLinkLongText":107,"extendedAnswerText":108,"headingVeryWrong":109,"youWereVeryWrong":104,"headingWrong":109},false,"1498",[39,60,77],{"metadata":40,"sys":43,"fields":56},{"tags":41,"concepts":42},[],[],{"space":44,"id":46,"type":21,"createdAt":47,"updatedAt":48,"environment":49,"publishedVersion":51,"revision":52,"contentType":53,"locale":34},{"sys":45},{"type":8,"linkType":18,"id":19},"2MlmjKfmaESo8QKAWIhsDR","2022-09-27T13:50:44.873Z","2025-01-22T13:44:13.382Z",{"sys":50},{"id":26,"type":8,"linkType":27},31,23,{"sys":54},{"type":8,"linkType":32,"id":55},"answer",{"globalId":57,"correctAnswer":36,"isVeryWrong":58,"answerText":59},"1498-a1",true,"Around 10% decline",{"metadata":61,"sys":64,"fields":74},{"tags":62,"concepts":63},[],[],{"space":65,"id":67,"type":21,"createdAt":68,"updatedAt":69,"environment":70,"publishedVersion":29,"revision":52,"contentType":72,"locale":34},{"sys":66},{"type":8,"linkType":18,"id":19},"5jDO93yFRlEHQdBUXbFY0U","2022-09-27T13:50:44.893Z","2025-01-22T13:44:13.418Z",{"sys":71},{"id":26,"type":8,"linkType":27},{"sys":73},{"type":8,"linkType":32,"id":55},{"globalId":75,"correctAnswer":36,"isVeryWrong":36,"answerText":76},"1498-a2","Around 40% decline",{"metadata":78,"sys":81,"fields":93},{"tags":79,"concepts":80},[],[],{"space":82,"id":84,"type":21,"createdAt":85,"updatedAt":86,"environment":87,"publishedVersion":89,"revision":90,"contentType":91,"locale":34},{"sys":83},{"type":8,"linkType":18,"id":19},"3jbPQFoC8NkTipnI8izYFw","2022-09-27T13:50:44.919Z","2025-01-22T13:44:13.454Z",{"sys":88},{"id":26,"type":8,"linkType":27},32,24,{"sys":92},{"type":8,"linkType":32,"id":55},{"globalId":94,"correctAnswer":58,"isVeryWrong":36,"answerText":95},"1498-a3","Around 70% decline",75,"Vertebrates population sizes","For all vertebrate species (animals with skeletons), how much did their wild populations decline on average during the past 50 years?",[100],"uk 0.75",[102],"uk 0.23","Vertebrate species declined by 73% over the past 50 years.","There has been a bigger decline across wild populations of mammals, birds, fish, amphibians and reptiles than you imagined.\n","There has been a bigger decline across wild populations of mammals, birds, fish, amphibians and reptiles than they imagined.\n","Source: Zoological School of London and WWF","Counting animals is extremely difficult and only a tiny fraction of all known species have been counted. The figures we use for this question come from the WWF’s and ZSL's Living Planet Index and it looks at nearly 35,000 populations of 5,495 species between 1970 and 2020. The data comes from results published by others, as the Living Planet Index has none of its own data collectors. For that reason, the species and study areas are not fully representative of all vertebrate species or areas (e.g. there are a lot of birds surveyed and a lot of surveys in North America and Europe compared to other continents). The 73% average given is within an uncertainty range of between 67% and 78%. And, as discussed above, it is vital to recognize that figure is an average across all of the animals surveyed. Some will have declined more and some would have had an increasing number. Despite these shortcomings, two independent experts we consulted for this question consider the Living Planet Index as a reliable source and that our correct answer is the best figure available. \n\nThe example of how to average out the declines was inspired by an example written in an article for The Atlantic by journalist Ed Yong. The piece is listed in the sources below.\n\n[1]  [WWF – Living Planet Report 2024](https:\u002F\u002Fwwflpr.awsassets.panda.org\u002Fdownloads\u002F2024-living-planet-report-a-system-in-peril.pdf) \n[2]  [The Atlantic - “Wait, Have We Really Wiped Out 60 Percent of Animals?” by Ed Yong, published on October 31, 2018](https:\u002F\u002Fwww.theatlantic.com\u002Fscience\u002Farchive\u002F2018\u002F10\u002Fhave-we-really-killed-60-percent-animals-1970\u002F574549\u002F)  \n[3]  [Wildlife Comeback Report 2022](https:\u002F\u002Frewildingeurope.com\u002Fwildlife-comeback-report-2022\u002F)  ","Counting animals is hard and any estimate of their numbers is a small snapshot of the situation. Of the vertebrate species that have been counted, there has been a 73% decrease on average between 1970 and 2020.\n\nThat does not mean that 73% of all wild mammals, birds, fish, amphibians and reptiles have disappeared in that time. That is the average across all populations. For example, say there are 5,000 panthers, 500 tigers and 50 polar bears (these are not real population numbers, just made up ones to explain). And then a few decades later, the number of panthers has declined 10% to 4,500, the number of tigers has declined 80% to 100 and the number of polar bears has declined 90% to just 5, that makes an AVERAGE decline of 60%. But the ACTUAL number of animals went down from 5,550 to 4,605 (which is a drop of just 17%).\n\nOf the nearly 35,000 animal populations that have been tracked back to 1970, around half have populations that have declined. That means that the average declines across those particular populations is higher than 73%. But, it also means that the other half of the animal populations studied have not been decreasing (for example the numbers of wolves, brown bears and white-tailed eagles in Europe have been INCREASING.)\n\nThe WWF says that the main reasons for the loss of wild animals are the “explosion in global trade, consumption and human population growth, as well as an enormous move towards urbanization.”\n\nBut the increase in some previously critically endangered populations show that targeted conservation efforts can be effective.\n\n### Why is it a problem that people are wrong about this?\nIt is vital to recognize how much some populations have declined so conservation and funding can be focused on the most threatened species.\n\n### Why are people wrong about this?\nPeople encounter birds and other animals on a daily basis so it can be hard to imagine just how much the populations of species have declined.  \n\n### Can I trust the data?\nYes, but it is important to understand what is measured and the weakness of the data. As mentioned above, counting animals is extremely difficult and only a tiny fraction of all known species have been counted. The figures we use for this question come from the WWF’s Living Planet Index and it looks at nearly 35,000 populations of 5,495 species between 1970 and 2020. The data comes from results published by others, as the Living Planet Index has none of its own data collectors. For that reason, the species and study areas are not fully representative of all vertebrate species or areas (e.g. there are a lot of birds surveyed and a lot of surveys in North America and Europe compared to other continents). The 73% average given is within an uncertainty range of between 63% and 75%. And, as discussed above, it is vital to recognize that figure is an average across all of the animals surveyed. Some will have declined more and some would have had an increasing number. Despite these shortcomings, two independent experts we consulted for this question consider the Living Planet Index as a reliable source and that our correct answer is the best figure available. \n","Unimaginable decline!"]