Rodents Prefer Going Downhill All the Way (Gravitaxis) Instead of Taking an Uphill Task

Abstract

We directly tested whether, when given the choice to ascend or descend, rodents would favor traveling downwards or upwards. The test incorporated different rodent species that dwell in different habitats and display different life and motor styles. Testing was performed in a three-dimensional Y-maze in which the basis was horizontal and, by rotating it, one arm of the maze could be pointing upwards at a certain angle and the other arm pointed downwards at the same angle. All the tested species displayed a general preference for descent, with rodents from complex habitats being less affected by inclination compared with rodents from flatlands. Unlike laboratory rats, wild species traveled greater distances along the lower compared to the upper maze arm. All the rodents initially tended to travel the entire length of the inclined maze arms, but such complete trips decreased with the increase in inclination. When introduced into the maze from top or bottom, flatland dwellers traveled mainly in the entry arm. Overall, when given the choice to ascend or descend, all the tested species displayed a preference to descend, perhaps as attraction to the ground, where they usually have their burrows.

Snakes on a slope: strong anti-gravitactic responses and differential habitat use in the Saharan horned viper ( Cerastes cerastes ) in the Negev desert

“…Additionally, the species' natural habitat plays a role in their reaction to the slope: species that live naturally in a complex environment are better at vertical exploration than those that live on plains [ 26 ]. Some species are also inclined to go down or up the slope—gravitaxis or anti-gravitaxis, respectively [ 24 , 27 , 28 ].…”

“…Thus, the dune's slope may set a challenge to larger animals but be irrelevant or even advantageous for smaller ones [21]. The effect of slope on animal movement and behaviour was studied in several vertebrate groups [10,20,[22][23][24]. For example, both field and laboratory studies have shown that animals avoid moving diagonally to the slope [19,25].…”