(S (S (S (PP-SBJ (NP (PP (PP (BASENP (NN 南)) (IN へ)) (IN の)) (NN 移動)) (IN は)) (ADJP (ADVP (RB 既に)) (ADVP (BASENP (NN 史上)) (ADJP (NN 最少) (MDV で))))) (COMMA 、) (S (PP (BASENP (JJ 厳しい) (NN 冬)) (IN に)) (COMMA 、) (S (PP-SBJ (NP (S (PP-SBJ (NP (PP (NP (PP (BASENP (DT その) (NN 種)) (IN の)) (BASENP (NN 個体) (NN 数))) (IN の)) (BASENP (NN 半分) (NN 以上))) (IN が)) (VP (VBV 死ん) (VP (MD だ)))) (BASENP (NN 可能) (NN 性))) (IN が)) (VP (VB ある))))) (PERIOD 。))
南 へ の 移動 は 既に 史上 最少 で 、 厳しい 冬 に 、 その 種 の 個体 数 の 半分 以上 が 死ん だ 可能 性 が ある 。
The southbound migration was already the smallest in recorded history , and with the destructive winter , over half of the species ' population might have been killed .