The loss of species on the daily basis is because of the human activities like deforestation, forest fires and exploitation of the species for their own use like overhunting, poaching, using animals resources like horns, teeth and other valuables.
The pollution can also be considered as an important factor for reduction of the species on the daily basis. Pollution may occur due to burning of the fossil fuels, discharge of sewage and other contaminants in the water. These activities are likely to kill the population of species to a number that population density of the species decrease, or the species may extinct.
Well, pollution is probably the main reason, but i think all of them are reasons why animals are dying off, if there isn't any choice for all of them, then your best bet would be to do a, pollution.
