Estimating the long-term repeatability of food-hoarding behaviours in an avian predator

Abstract

Food-hoarding behaviour is widespread in the animal kingdom and enables predictable access to food resources in unpredictable environments. Within species, consistent variation among individuals in food-hoarding behaviours may indicate the existence of individual strategies, as it likely captures intrinsic differences in how individuals cope with risks (e.g. starvation, pilferage). Using 17 years of data, we estimated the long-term repeatability of 10 food-hoarding behaviours in a population of Eurasian pygmy owls ( Glaucidium passerinum ), a small avian predator subject to high temporal fluctuations in its main prey abundance. We found low repeatability in the proportion of shrews and the average prey mass stored for both sexes, while females were moderately repeatable in the mass and the number of prey items stored. These two pairs of behaviours were tightly correlated among individuals and might represent two different sets of individual strategies to buffer against starvation risks.

The influence of spatial memory on caching behaviour and reproductive success in the North Island robin (Petroica longipes)

“…suggests that individuals are repeatable in the long-term in certain aspects of their caching, such as the type, amount, and mass of prey items stored (Class et al, 2021). How these different repeatable aspects of caching interrelate remains unclear, however.…”

“…Typically, researchers can gain only a small snapshot into a species' caching, by locating caches and their contents after the fact, or via an indirect measure of caching such as the rate at which seeds are carried away from a feeder (e.g., Ekman et al, 1996;Lahti et al, 1998;Petit et al, 1989;Waite & Reeve, 1995). In a study finding repeatability in various aspects of Eurasian pygmy owl (Glaucidium passerinum) caching, only the final product of caching was quantifiable, such as the number of items stored, their mass, and the type of prey (Class et al, 2021). Likewise, in Merriam's kangaroo rats (Dipodomys merriami), caching was similarly quantified based on the final distribution of caches after storage had been completed (Jacobs, 1992;Jenkins & Peters, 1992).…”

“…Much less is known regarding how individuals of the same species differ in their caching behaviour, but recent findings suggest that caching can vary considerably between conspecifics. Class et al (2021) found that the number and mass of cached prey items are significantly repeatable in Eurasian pygmy owls (Glauicidium passerinum), while Croston et al (2016) found that individual differences in the rate at which mountain chickadees (Poecile gambeli) cached seeds from artificial feeders was related to spatial memory. In a mammalian caching species, Merriam's kangaroo rat (Dipodomys merriami), individuals varied in the spatial density of their caches (Dochtermann & Jenkins, 2007).…”

“…This paucity of research likely reflects the logistical challenges involved in quantifying natural caching behaviour: directly observing caching in the field is difficult, due to the large spatiotemporal scale of many species' caching, as well as the natural wariness of wild birds to direct human observation (Ekman et al, 1996;Morand-Ferron et al, 2016). As a result, only a limited portion of caching behaviour is quantifiable in most study systems-for instance, aspects such as the contents of cache sites are more easily measurable than the act of caching itself (Class et al, 2021). Quantifying detailed intraspecific variation in caching behaviour requires a study system in which the caching behaviour of individual wild birds can be repeatedly observed.…”