¿which animal is it about? The voles. This is contemplated by a new study led by the Institute of Zoology, the Chinese Academy of Sciences, the Northeast China Normal University and the universities of Exeter and Florida and published in the journal Current Biology.
Until now, little was known about the consequences of engineering activity by prey species that modify the environment to reduce the risk of being eaten. In Inner Mongolia, the researchers decided to test how the behavior of voles ( arvicolinos ) changed when there is an increased presence of predatory birds called shrikes ( Laniidae ).
Shrike often perch on the branches and stems of bushes and tall grasses to search for prey such as these rodents and large insects. They store their food by impaling their prey on a thorn or stem, much like storing food on a meat hook.
The study focused on Brandt’s vole ( Lasiopodomys brandtii) , which is native to scrub and grasslands in Russia, Mongolia and northern China.
What happened?
They observed that the voles did not eat or use the grass , but instead cut it to keep themselves safe; an example of “ecosystem engineering”. Voles attack the lower parts of the stem and leaves and drop them to the ground. They also dig burrows that lead to cut roots.
“When the shrikes were present, the voles dramatically reduced the volume of grass,” says Dirk Sanders of the Institute for Environment and Sustainability at Exeter’s Penryn Campus in Cornwall. “This led to fewer visits by shrikes, which apparently recognize grass-cut areas as poor hunting grounds. An activity like this is costly for the voles in terms of energy, so there must be high ‘selection pressure’.” to do it: mowing the lawn should significantly improve your chances of survival.
Thus, the voles actively modified the habitat by cutting down a large grass species in the presence of shrikes.
What if the threat disappeared?
They experimented with this possibility, keeping the birds away from these small rodents. The result was that, seeing no shrikes overhead, the voles stopped cutting tall grass— that is, this behavior disappeared when the researchers experimentally excluded these avian predators, using nets.
“Sometimes we underestimate the ability of wild animals to react to changes in their environment,” says Sanders. “Our findings are a reminder that species show remarkable adaptations . It also underlines that the loss of even a single species in a food web can cause unexpected changes to an entire habitat.”
More examples of ecosystem engineering
Other examples include elephants opening up areas of African savannah or fish reducing seagrass canopy height (off the Catalan coast), but this makes the areas safer for other species rather than their own.
Reference: Zwiwei Zhong et al. A rodent herbivore reduces its predation risk through ecosystem engineering. March 11, 2022Current Biology. DOI:https://doi.org/10.1016/j.cub.2022.02.074
