Accompanying R code from Special delivery: scavengers direct seed dispersal towards ungulate carcasses

Cadaver decomposition-islands around animal carcasses can facilitate establishment of various plant life. Facultative scavengers have great potential for endozoochory, and often aggregate around carcasses. Hence, they may disperse plant seeds that they ingest across the landscape towards cadaver decomposition-islands. Here, we demonstrate this novel mechanism along a gradient of wild tundra reindeer carcasses. First, we show that the spatial distribution of scavenger faeces (birds and foxes) was concentrated around carcasses. Second, faeces of the predominant scavengers (corvids) commonly contained viable seeds of crowberry, a keystone species of the alpine tundra with predominantly vegetative reproduction. We suggest that cadaver decomposition-islands function as endpoints for directed endozoochory by scavengers. Such a mechanism could be especially beneficial for species that rely on small-scale disturbances in soil and vegetation, such as several Nordic berry-producing species with cryptic generative reproduction.

动物尸体周边形成的尸体分解岛（cadaver decomposition-islands），可助力多种植物完成定植。兼性食腐动物拥有极强的消化道传播（endozoochory）潜力，且常聚集于尸体周围。据此，它们可将摄入的植物种子扩散至整个生境，并最终导向尸体分解岛。本研究沿冻原野生驯鹿尸体的分布梯度展开，验证了这一全新机制。首先，我们证实食腐动物（鸟类与狐类）的粪便空间分布显著聚集于尸体附近；其次，优势食腐类群（鸦科鸟类）的粪便中，常含有岩高兰（crowberry）的存活种子——岩高兰作为高山冻原的关键物种，其繁殖以营养繁殖为主。我们提出，尸体分解岛可作为食腐动物定向消化道传播的终点。此类机制对于依赖土壤与植被小型扰动的物种尤为有益，例如数种具备隐蔽有性繁殖特性的北欧浆果类植物。