Decline in wild mammal populations
Ecological trend / From Wikipedia, the free encyclopedia
The decline of wild mammal populations globally has been an occurrence spanning over the past 50,000 years, at the same time as the populations of humans and livestock have increased. Nowadays, the total biomass of wild mammals on land is believed to be seven times lower than its prehistoric values, while the biomass of marine mammals had declined fivefold. At the same time, the biomass of humans is "an order of magnitude higher than that of all wild mammals", and the biomass of livestock mammals like pigs and cattle is even larger than that. Even as wild mammals had declined, the growth in the numbers of humans and livestock had increased total mammal biomass fourfold. Only 4% of that increased number are wild mammals, while livestock and humans amount to 60% and 36%. Alongside the simultaneous halving of plant biomass, these striking declines are considered part of the prehistoric phase of the Holocene extinction.[2][1]
Since the second half of the 20th century, a range of protected areas and other wildlife conservation efforts (such as the Repopulation of wolves in Midwestern United States) have been implemented. These have had some impact on preserving wild mammal numbers.[3] There is still some debate over the total extent of recent declines in wild mammals and other vertebrate species.[4][5] In any case, many species are now in a worse state than decades ago.[6] Hundreds of species are critically endangered.[7][8] Climate change also has negative impacts on land mammal populations.[3]