Data from: A migratory northern ungulate in the pursuit of spring: jumping or surfing the green wave?

The Forage Maturation Hypothesis (FMH) states that herbivores migrate along a phenological gradient of plant development in order to maximize energy intake. Despite strong support for the FMH, the actual relationship between plant phenology and ungulate movement has remained enigmatic. We linked plant phenology (MODIS-NDVI) and space use of 167 migratory and 78 resident red deer (Cervus elaphus) using a space-time-time matrix of "springness", defined as the instantaneous rate of green-up (IRG). Consistent with the FMH, migrants experienced substantially greater access to early plant phenology than residents. Deer were also more likely to migrate in areas where migration led to greater gains in springness. Rather than "surfing the green wave" during migration, migratory red deer moved rapidly from the winter to the summer range, thereby "jumping the green wave". However, migrants, and to a lesser degree residents, did track phenological green-up through parts of the growing season by making smaller-scale adjustments in habitat use. We conclude that, whereas in some systems migration itself is a way to surf the green wave, in others it may simply be a means to re-connect with phenological spring at the summer range.

食物成熟假说（Forage Maturation Hypothesis, FMH）指出，草食动物会沿植物发育的物候梯度进行迁徙，以最大化自身的能量摄入。尽管现有研究已为该假说提供了强有力的支撑，但植物物候与有蹄类动物移动之间的实际关联始终悬而未明。
我们以被定义为瞬时返青速率（instantaneous rate of green-up, IRG）的‘返青度’构建时空矩阵，将植物物候数据（MODIS归一化差值植被指数，MODIS-NDVI）与167只迁徙型、78只居留型马鹿（Cervus elaphus）的空间利用模式进行了关联分析。结果与食物成熟假说一致：迁徙型马鹿相较于居留型个体，能够更早接触到处于发育早期的植物；马鹿更倾向于在那些通过迁徙可获得更大返青度提升的区域开展迁徙活动。
与‘顺绿波冲浪’的预期不同，迁徙型马鹿并未在迁移过程中追踪物候进程，而是快速从越冬分布区转移至夏栖分布区，借此‘跃过绿波’。不过，迁徙型种群（以及程度较轻的居留型种群）仍会在生长季的部分时段，通过调整局域生境利用来追踪物候返青进程。
我们的研究结论表明，尽管在部分生态系统中，迁徙本身就是‘顺绿波冲浪’的有效途径，但在其他生态系统中，迁徙或许仅仅是为了在夏栖分布区重新衔接物候春季的手段。