Experiments show that changes in day length （）the migrations of

Experiments show that changes in day length （）the migrations of many species of birds．

accumulate

calculate

formulate

stimulate

句意：实验表明，白天时长的变化会刺激许多鸟类的迁徙。stimulate：刺激，符合句意；accumulate：积累； calculate：计算；formulate：制定，格式化。