Food Caching Behavior in Pikas
Studies and questions about the adaptive value of an animal behavior provide us with functional explanations which describe the utility of the current form of the behavior. This involves investigating how a behavior increases an organism’s overall lifetime reproductive success.
Adaptive Value of Food Caching
Food caching allows herbivores such as pikas to manage food availability despite conditions such as low plant biomass, competition from other herbivores, and risks of predation (Morrison et al. 2009). Pikas live in tundra habitats where plant biomass is very low during the winter months. Though pikas exhibit grazing behavior year-round, caching is only performed from July through September when biomass has peaked (Huntly et al. 1986). The higher availability of food during this time makes caching easier and preserves time during the winter for the pikas to graze. The caches alone are not enough to sustain the pikas through winter, but they serve as insurance to prevent starvation in case of a food shortage.
Variation in foraging behaviors
Some populations of pikas have developed new adaptations to low plant availability. In an area where vegetation has been significantly reduced by climate change factors, around 60% of the pikas diet was comprised of moss, despite its low nutritional value. These pikas also did not build the caches during the growing season and instead focused their energy on grazing from the sparse vegetation (Varner and Dearing 2014). This indicates that foraging behavior is plastic and can be altered to increase survival according to environmental strains.
Kleptoparasitism has also been observed to varying degrees in some pika populations. Stealing caches from other pikas cuts down on the cost of gathering food, but the frequency of this behavior is kept fairly low by territorial cache-guarding (McKetchnie 1994).
These alternative foraging behaviors allow pika’s to maximize their lifetime reproductive fitness under various conditions.