星鸦的贮食行为及其对红松种子的传播作用

HOARDING BEHAVIOR OF EURASIAN NUTCRACKER (NUCIFRAGA CARYOCATACT) AND ITS ROLE IN SEED DISPERSAL OF KOREAN PINE (PINUS KORAIENSIS)

1994～ 1998年秋在小兴安岭凉水自然保护区对星鸦 (Nucifragacaryocatact)的贮食行为及其对红松(Pinuskoraiensis)种子的传播作用进行了研究。星鸦在秋季至翌年早春主要以红松种子为食 ,偶食浆果。秋季种子成熟时 ,星鸦在取食的同时储藏大量种子作为冬季和早春的食物 ,这些种子中未被完全吃掉的遗留部分在第三年春天即可发芽。在树上取食部分种子后 ,星鸦通常储存 30～ 5 0粒于舌下囊中 ,飞行 2～ 5km后 ,将种子埋藏在土层下 2 5～ 3 5cm深处 ,每个贮点多为 2～ 4粒。贮点生境主要有 8种 :林缘 (路边 )、保护区周围空阔地、人工落叶松林、人工臭冷杉林、人工红松林、人工红皮云杉林、天然更新的杨桦林和天然原始红松阔叶林(母树林 )。星鸦每天至少搬运种子 10次 ,达 40 0粒。一个贮藏季节一只星鸦可贮藏至少 16 0 0 0粒种子。对红松1年生和 2年生幼苗调查表明 ,幼苗在上述 8种生境中均有分布 ,并且在人工落叶松林、天然更新杨桦林和母树林下有幼树分布。因此星鸦能有效地扩散红松种子 ,有利于红松的天然更新。

We studied the seed hoarding behavior of Eurasian nutcrackers from 1994-1997 at Liangshui Nature Reserve, which located at Xiaoxinganling Mountains. It was founded for conserving the virgin Korean pine hard wood forest. Eurasian nutcrackers mainly feed on the Korean pine seed from autumn to next early spring. When cones become ripe, nutcrackers begin to harvest seeds and store a lot for winter and next spring. Nutcrackers are good at collecting seeds from the cone and swallowing. Occasionally, nutcrackers stop to crack some seeds and eat the kernel, seed coat become two half parts. After eating some seeds in the tree, nutcrackers carry 30-50 seeds with their sublingual pouch to some places 2-5 km far generally, and cach the seeds 2 5-3 5 cm deep under ground in common. Nutcrackers jab caches with bill on the ground, 2-5 times for one cache. 2-4 seeds are buried under each cache generally. Cache sites mainly are found at 8 types of habitats: roadside (forest edge), open area around protecting station, Larix plantation, Abies plantation, Pinus koraiensis plantation, Picea plantation, Populus Betula natural regeneration and natural Korean pine hard wood. One nutcracker can store 16 000 seeds in one harvest season (about 40 days in research site). Nutcrackers dont recover all the caches and reforage all seeds. Untouched seeds may germinate in the second spring in about 18 months since being cached. 1 year and 2 year seedlings, which usually appear with 2-4 seedlings in one cluster, are found in all the 8 types of habitats around research sites, but saples (higher than 3 m) are only found in Larix plantation, Populus Betula natural regeneration and natural Korean pine hard wood. Such situation is decided by growing characteristics of Korean pine. Nutcracker is an effective disperser of the Korean pine seeds.