Ungulates rely less on visual cues, but more on adapting movement behaviour, when searching for forage

Abstract

Finding suitable forage patches in a heterogeneous landscape, where patches change dynamically both spatially and temporally could be challenging to large herbivores, especially if they have no a priori knowledge of the location of the patches. We tested whether three large grazing herbivores with a variety of different traits improve their efficiency when foraging at a heterogeneous habitat patch scale by using visual cues to gain a priori knowledge about potential higher value foraging patches. For each species (zebra (Equus burchelli), red hartebeest (Alcelaphus buselaphus subspecies camaa) and eland (Tragelaphus oryx)), we used step lengths and directionality of movement to infer whether they were using visual cues to find suitable forage patches at a habitat patch scale. Step lengths were significantly longer for all species when moving to non-visible patches than to visible patches, but all movements showed little directionality. Of the three species, zebra movements were the most directional. Red hartebeest had the shortest step lengths and zebra the longest. We conclude that these large grazing herbivores may not exclusively use visual cues when foraging at a habitat patch scale, but would rather adapt their movement behaviour, mainly step length, to the heterogeneity of the specific landscape.

The Effect of Novel and Familiar Predator Cues on Prey Vigilance and Foraging Behaviors in the Greater Khingan Mountains, Inner Mongolia, China

“…Also, our results demonstrate that when prey animals occur in a fearful environment due to limitations of factors like food availability, mating, and dispersal; they display selectivity or even ignore cue use so as to maximise energy intake (Lima and Bednekoff, 1999;Eccard et al, 2017). Likewise, our results tell the differences in how species respond towards predator risk, that small body size animals (roe deer) are potentially at high risk from various predators compared to large size (moose) which are mostly limited by food (foraging) (Rogers, 2016;Venter et al, 2017). Our results also indicate that due to differences in historical background, it is essential to consider each species differently when considering predation risk or cue use effects of different prey species.…”

“…ignoring cues that may be inaccurate) in order to maximise energy intake (Lima and Bednekoff, 1999;Eccard et al, 2017). Additionally, our results reveal differences in how species (roe deer and moose) respond towards predator cues, potentially because body size may effect on how species respond to predation risk (Rogers, 2016;Venter et al, 2017).…”

“…We think that we were not able to see the effect because (from the previous submitted study) we saw that these species are already using the landscape differently, so perhaps it might be that those using these areas have already adjusted their behaviours. Venter et al (2017) suggested that ungulates depend less on visual cues when searching for food (relative to movement behaviors), possibly because it is easier to incorporate auditory cues while foraging with head down, than visual cues, which require the cessation of foraging to lift the head. Auditory cues may also be more likely to be accurate and up-to-date than olfactory cues (Shelton and Kumar, 2010).…”

Foraging ecology of masked boobies (Sula dactylatra) in the world’s largest “oceanic desert”

“…Flying fish shoals are highly unpredictable (Oxenford et al 1995); traveling to the same area is thus of limited value to masked boobies, and it may be more efficient to search in different locations. Other animals facing unpredictable resources move without any specific direction but then travel directly when they see something of interest (Venter et al 2017). This seems to reflect the behavior of masked boobies searching for a prey patch, subsurface predators, or conspecifics.…”