Abstract
Maximising survival requires animals to balance the competing demands of maintaining energy balance and avoiding predation. Here, quantitative modelling shows that optimising the daily timing of activity and rest based on the encountered environmental conditions enables small mammals to maximise survival. Our model shows that nocturnality is typically beneficial when predation risk is higher during the day than during the night, but this is reversed by the energetic benefit of diurnality when food becomes scarce. Empirical testing under semi‐natural conditions revealed that the daily timing of activity and rest in mice exposed to manipulations in energy availability and perceived predation risk is in line with the model’s predictions. Low food availability and decreased perceived daytime predation risk promote diurnal activity patterns. Overall, our results identify temporal niche switching in small mammals as a strategy to maximise survival in response to environmental changes in food availability and perceived predation risk.
Highlights
Survival of animals in the wild depends on their ability to avoid predation and obtain sufficient food to meet energetic needs (Sih 1980; McNamara & Houston 1987; Lima & Dill 1990)
Our results confirm the importance of daily activity timing for the survival of small mammals under natural conditions (Daan 1981; Kronfeld-Schor & Dayan 2003) and extend this understanding by identifying circadian flexibility as a strategy employed by mice to maximise survival depending on the encountered environmental conditions
Diurnality is associated with reduced energetic demands (Levy et al 2012; van der Vinne et al 2015), this energetic benefit needs to be balanced against typically higher predation risk during the day (Halle 1993; Moreno et al 1996; Gerkema et al 2013)
Summary
Survival of animals in the wild depends on their ability to avoid predation and obtain sufficient food to meet energetic needs (Sih 1980; McNamara & Houston 1987; Lima & Dill 1990). Most small mammals are typically nocturnal (Roll et al 2006; Bennie et al 2014), but shifts to diurnality are common in response to energetic challenges or increased night-time predation (Hut et al 2012; van der Vinne et al 2014), suggesting temporal niche switching as a strategy to maximise survival in response to environmental changes. The influence of daily activity timing on the survival of small mammals has only been considered in general (non-quantitative) terms (Daan 1981; Lima & Dill 1990; Kronfeld-Schor & Dayan 2003; Hut et al 2012), preventing a full assessment of the implications of daily rhythms for the foraging/predation risk trade-off. We present a quantitative framework to predict the optimal temporal niche based on the encountered environmental conditions and test its predictions in mice (Mus musculus) living in outdoor enclosures by manipulating perceived predation risk and food availability
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