What if Eurasian jay Garrulus glandarius would larder acorns instead of scatter them?

Abstract

Jays usually store acorns at separate sites, but in some cases a part of jay’s caches consists of more than one acorn. Storing acorns separately (scatter hoarding) or in clusters (larder hoarding) seems to be an important factor for further survival of seeds and seedlings. Scatter hoarding is favorable for jays, but what would happen if jays prepared caches consisting of more than one acorn? We put a following question: what is the importance and impact of acorn concentration per cache for the seedlings’ mortality and their growth characteristics? In 2013 an experimental plot was established. 1400 acorns of Quercus robur L. were sewed in 600 holes in three combinations called growing mode - singly, in twos and in fours. The mortality of seedlings depended on growing mode (Z = 6.24, P < 0.001) and year (Z = -2.42, P = 0.016). In the third year of the experiment the mortality of seedlings growing from acorns sewed in fours reached almost 90%, while in the case of seedlings growing separately the mortality was stable, reaching no more than 23%. Both growing mode (F = 26.49, P < 0.001) and year (F = 52.59, P < 0.001) had a significant impact on seedling growth increment. Seedlings growing in fours had a significantly higher growth increment than these growing separately and in twos. We concluded that seedlings growing separately had a higher survival rate, but lower growth increment than those coming from acorns sewed in clumps.