Marmots do not consistently use their left eye to respond to an approaching threat but those that did fled sooner

Abstract

In many vertebrates, the brain’s right hemisphere which is connected to the left visual field specializes in the processing of information about threats while the left hemisphere which is connected to the right visual field specializes in the processing of information about conspecifics. This is referred to as hemispheric lateralization. But individuals that are too predictable in their response to predators could have reduced survival and we may expect selection for somewhat unpredictable responses. We studied hemispheric lateralization in yellow-bellied marmots Marmota flaviventer, a social rodent that falls prey to a variety of terrestrial and aerial predators. We first asked if they have lateralized responses to a predatory threat. We then asked if the eye that they used to assess risk influenced their perceptions of risk. We recorded the direction marmots were initially looking and then walked toward them until they fled. We recorded the distance that they responded to our experimental approach by looking, the eye with which they looked at us, and the distance at which they fled (i.e., flight initiation distance; FID). We found that marmots had no eye preference with which they looked at an approaching threat. Furthermore, the population was not comprised of individuals that responded in consistent ways. However, we found that marmots that looked at the approaching person with their left eye had larger FIDs suggesting that risk assessment was influenced by the eye used to monitor the threat. These findings are consistent with selection to make prey less predictable for their predators, despite underlying lateralization.

Increased Flight Initiation Distance (FID) in Golden Marmots (Marmota caudata aurea) Responding to Domestic Dogs in A Landscape of Human Disturbance

“…The experimenter dropped a flag at each of the following: (i) the point of onset of the approach; (ii) experimenter position when the focal marmot responded to the approach (e.g., by moving its head in experimenter’s direction); and (iii) experimenter location when the marmot started to flee, usually by running into a burrow. Subsequently, the following were recorded using a standard tape measure: (i) starting distance SD (first flag to initial position); (ii) alert distance AD (second flag to initial position); and FID (third flag to initial position), all as straight-line measurements in meters [45].…”

“…A backwards model selection procedure was then employed where all fixed main effects and interactions were initially entered together before sequential removal of non-significant variables at the 95% level, based on lowest deviance ( F ) values. We included colony ID as a random effect in the model, to account for repeat observations of the same colonies over time [45]. Initially, individual ID was additionally included as a random factor, but poor model fit (i.e., lack of convergence) resulted in removal of this variable.…”

Occurrence of Conspecific in the Neighboring Space Influence on Flight Initiation Distance in Cape Hare <i>Lepus capensis</i> under Human Stimuli

“…61), with remaining candidate fixed variables explained in Table 1. We fitted generalized linear mixed-effect models with a Poisson error structure using the R packages lme4 and lmerTest [37]. We assumed that risk influence on a hare's FID may be related to 1) group size effect, 2) terrain types and 3) anthropogenic threats.…”

Lateralization of vigilance in geese: influence of flock size and distance to the source of disturbance

“…Antipredator behaviour has been studied in a wide variety of species ranging from invertebrates to fish, mammals, and birds (De Santi et al, 2001;Rogers, 2002;Schnell et al, 2016;Romano et al, 2017). The right brain hemisphere and the left eye have been found to be responsible for vigilant behaviour in many species (Rogers and Kaplan, 2005;Martín et al, 2010;Austin and Rogers, 2012;Bonati et al, 2013). However, some studies on animals in the wild failed to confirm the consistent use of the left eye to monitor predators (Franklin and Lima, 2001;Randler, 2005;Beauchamp, 2013).…”