Canada Jay (Perisoreus canadensis) harvesting and caching fruits of Thin-leaved Snowberry (Symphoricarpos albus)

Résumé

On 17 September 2021, we observed three Canada Jay (Perisoreus canadensis) harvesting and caching Thin-leaved
Snowberry (Symphoricarpos albus) fruits in a mixed conifer forest in western Montana, USA. Thin-leaved Snowberry has
not been reported previously in their diet. During 3 min of direct observation, each jay harvested snowberries similarly and cached them on the trunks of nearby pines. In each case (11 caches), the jay flew by the snowberry shrubs twice, plucking a fruit while airborne, landing on the ground between passes, the first fruit carried in the throat, the second in the bill. The jays then landed, most often out of view on tree trunks, but, nevertheless, appeared to cache the fruits each time. One cache observed in the making contained two harvested fruits wedged in a crevice on the trunk and covered with a flake of bark. Thin-leaved Snowberry is considered a low-quality fall-ripening fruit because of the small energy gain for each fruit consumed. Nevertheless, the energy density of snowberries (16.65 kJ/g dry mass) collected at the same location in October exceeded that required by non-migratory Canada Jays for daily maintenance during winter. It is unlikely jays could cache enough fruits each day to sustain them for several winter months. Instead, snowberries could be an important and readily available autumn and winter food for Canada Jays resident in this region when used to supplement other stored foods with greater energy, fat, and protein content.