Refrigeration or anti-theft? Food-caching behavior of wolverines (Gulo gulo) in Scandinavia

Abstract

Food-caching animals can gain nutritional advantages by buffering seasonality in food availability, especially during times of scarcity. The wolverine (Gulo gulo) is a facultative predator that occupies environments of low productivity. As an adaptation to fluctuating food availability, wolverines cache perishable food in snow, boulders, and bogs for short-and long-term storage. We studied caching behavior of 38 GPS-collared wolverines in four study areas in Scandinavia. By investigating clusters of GPS locations, we identified a total of 303 food caches from 17 male and 21 female wolverines. Wolverines cached food all year around, from both scavenging and predation events, and spaced their caches widely within their home range. Wolverines cached food items on average 1.1 km from the food source and made between 1 and 6 caches per source. Wolverines cached closer to the source when scavenging carcasses killed by other large carnivores; this might be a strategy to optimize food gain when under pressure of interspecific competition. When caching, wolverines selected for steep and rugged terrain in unproductive habitat types or in forest, indicating a preference for less-exposed sites that can provide cold storage and/or protection against pilferage. The observed year-round investment in caching by wolverines underlines the importance of food predictability for survival and reproductive success in this species. Increasing temperatures as a consequence of climate change may provide new challenges for wolverines by negatively affecting the preservation of cached food and by increasing competition from pilferers that benefit from a warmer climate. It is however still not fully understood which consequences this may have for the demography and behavior of the wolverine. Significance statementFood caching is a behavioral strategy used by a wide range of animals to store food for future use. Choosing appropriate caching sites appears important for slowing down decomposition rates and minimizes competition. In this study, we demonstrate that the wolverine, an opportunistic predator and scavenger, utilizes available carrion to create caches all year around. By following wolverines with GPS collars, we registered that they carried food far away to cache it in secluded and cold places, which are often located on steep slopes or in forest. However, when scavenging other carnivores' prey, they move food in shorter distances, possibly to be able to quickly return for more. The observed efficiency in wolverine caching behavior is likely vital for their survival and reproductive success in the harsh and highly seasonal environment in which they live.

Digging into the behaviour of an active hunting predator: arctic fox prey caching events revealed by accelerometry

“…Furthermore, as arctic foxes are territorial and tend to avoid territory borders [ 40 ], their territoriality could lead to non-random distribution of specific behaviours. For example, caches could be preferentially located away from territory edges to reduce pilferage, as observed in wolverines ( Gulo gulo ) that tend to cache food in sites less exposed to competitors [ 25 ]. Another interesting avenue would be to directly assess arctic fox tendencies to do cache pilfering in neighbour territories or along overlapping areas.…”

“…Food caching (e.g. [ 23 – 25 ]) is one such sequence, as observed in many canids, which are active hunting predators storing food for later consumption [ 26 ]. Canid caching behaviour generally follows a distinctive sequence of food carrying, digging with forepaws, tamping with muzzle to press food into the soil, and head scooping to cover food with substrate [ 27 ].…”

Food caching by a solitary large carnivore reveals importance of intermediate-sized prey

“…Consistent with this reasoning, brown bears also do not cache fawns or double kills more frequently than other prey (Cristescu et al 2014). While previous carnivore studies (e.g., Teurlings et al 2020) have linked caching to delayed invertebrate activity that slows decomposition, the sole study investigating this effect in pumas (Bischoff- Mattson and Mattson 2009) buried ungulate carcasses to simulate caching and monitored carcass decomposition compared to unburied carcasses rather than monitoring actual puma kills.…”

Chromosomal-level reference genome assembly of the North American wolverine (Gulo gulo luscus): a resource for conservation genomics

“…1, a and b ). The wolverine’s utilization of deep and long-lived snowpack for denning structures ( Copeland et al 2010 ) and food-caching locations ( van der Veen et al 2020 ) are behavioral adaptations to this harsh climatic niche. The wolverine is also physiologically adapted to cold and snowy environments with stocky build and thick fur for heat retention, wide paws and plantigrade stride to walk on top of snow, and skull characteristics, including an enlarged sagittal crest and zygomatic arch, muscular head, and strong dentition to enable them to crush through frozen bone and meat ( Copeland and Whitman 2003 ).…”