When dinosaurs roamed the earth, mammals were nocturnal. They had to be to avoid being eaten. Now there are other big bad creatures terrorizing mammals and forcing them to once again find refuge during the day and only come out at night: us, humans.
It is well established that we have shifted where many wild species go about their daily activities as we’ve left them fewer and fewer places to live. But any temporal disturbances we may have caused have not been as deeply studied as these spatial ones. Now, environmentalists at UC Berkeley and Boise State University have done a meta-analysis of 76 temporal studies, covering 62 mammalian species from six continents (all of the mammals in Antarctica are marine). All but five of the studies were done this century.
They found that mammal nocturnality increased by a factor of 1.36 in areas or periods with high human disturbance. This means that, if an animal normally split its activity evenly between day and night, humans’ activity is associated with an increase in the animals’ proportion of nighttime activity to 68 percent. This was true across the board: for small mammals like opossums and large ones like African elephants; for apex carnivores as well as their prey; in Argentina and California and Zimbabwe and Nepal and Poland and everywhere else they looked.
Source: FS – All – Science – News
The humans are coming! HIDE!