Seed removal and survival in Asiatic black bear Ursus thibetanus faeces: effect of rodents as secondary seed dispersers

Abstract

We investigated the fate of seeds of five tree species hill cherry Prunus jamasakura, Korean hill cherry P. verecunda, Japanese bird cherry P. grayana, giant dogwood Swida controversa and crimson glory vine Vitis coignetiae in the faeces of the Asiatic black bear Ursus thibetanus in a temperate forest in central Japan. Clarifying the fate of seeds dispersed by endozoochorous seed dispersers will enhance assessments of their roles as primary seed dispersers. We established several experimental treatments in the field. Each faeces sample was covered by cages with different mesh sizes which limited accessibility by animals (NM: no mesh, SM: 1 mm mesh and MM: 10 mm mesh). We examined whether seed removal varied among tree species and between mesh‐size treatments from 2004 to 2007 (N = 625 samples). We set up an automatic camera trap 1.5 m above the ground at all NM treatments. In the NM treatments, the number of seeds of all tree species decreased immediately after the faeces were set. In June of the following year, < 1% of the seeds from any species remained in the vicinity of the faeces. However, we found 3.0‐13.2% intact seeds of all species in the soil below the faeces, as well as within a 10‐m radius around the faeces. In the NM treatments, most seed removals were observed within four days after the faeces were set. For all tree species in the MM treatment, most of the seeds were present on the surface of the soil, and 1‐2% of the seeds germinated at the location where faeces were set. In the SM treatment, none of the seeds from any of the tree species disappeared and germinated. We took a total of 415 photographs at the NM sites, 97.8% of which were of rodents either holding or eating seeds. Many of the seeds contained in the bear faeces were removed and eaten by rodents. However, 2.1‐5.1% of the seeds survived and germinated, which implies that rodents may also act as secondary seed dispersers.

Seed dispersal potential of jackals and foxes in semi-arid habitats of South Africa

“…Through defecation, animals deposit the seeds at various distances from the source plant, called seed shadows, which are dependent on animal movements and gut retention times (Koike et al, 2010). Successful germination and seedling establishment within seed shadows is greatly affected by the microhabitat of the a a defecation sites (Chavez-Ramirez and Slack, 1993), and sometimes secondary movements of seeds after defecation (Koike et al, 2012). By influencing the spatial distribution and demography of the plants they feed on, seed dispersers may shape the vegetative landscape and contribute to the natural regeneration of ecosystems (Wisz et al, 2013;Baños-Villalba et al, 2017).…”

Synergistic effects of primates and dung beetles on soil seed accumulation in snow regions

“…To protect the experimental fecal piles from nat-ural disturbances (such as rain and rodents), we covered each pile with a wire cage (30 cm · 20 cm · 20 cm; 1-cm mesh size) with a roof. The mesh size used allowed free passage of all dung beetles observed in cool-temperate forests of Japan (Koike et al 2012a). After 1 month we collected soil samples within a radius of 10 cm from each fecal pile.…”

“…Formation of a soil seed bank for endozoochorous plant species requires primary seed dispersal by vertebrates in order to escape the area of high seed mortality near the parent plant, and may be further facilitated through secondary seed dispersal by other animals that transport seeds to sites that are safe from seed predators Longland 2004, 2005;Dalling 2005;Feer et al 2013). Rodents and granivorous ants are known to act as secondary seed dispersers because of their scatter-hoarding behavior, but they are also recognized as seed predators (Forget 1996;Retana et al 2004Koike et al 2012a). Other ant types do not eat the seeds, but they collect only elaiosome-bearing seeds, in particular those that have been dispersed by birds (Bo¨hning-Gaese et al 1999;.…”

Ecological Role of Japanese Macaques in Maintaining Biological Diversity in Heavy Snowfall Areas

“…) 。また，幸運にも セーフサイトへ一次散布された種子であっても，齧歯 目による採食や貯食のための持ち去りが頻繁に発生す る (Janzen, 1982;Andresen, 1999;Koike et al, 2012b (Chambers & MacMahon, 1994;Vander Wall & Longland, 2004, 2005Dalling, 2005;Feer et al, 2013) Böhning-Gaese et al, 1999; 。一方で，熱帯や温帯において，分解生物の中で バイオマスが際立って大きい食糞性コガネムシ(コガ ネムシ上科に属する甲虫類 Coleoptera: Scarabaeinae; 以 下，糞虫と略記)は，多様な種子を土壌内に移動させ ることができる二次散布者として知られており，その 機能の解明に向けた研究は注目を集めている (Andresen & Feer, 2005;Vulinec et al, 2006;Nichols et al, 2008) Davis et al, 2002;Philips, 2011) Feer, 2005;Nichols et al, 2008) (Enari et al, 2011(Enari et al, , 2013(Enari et al, , 2016) 。その結果，住込み屋 11 種，穴掘り屋 7 種， 転がし屋 1 種，計 19 種をこれまでに確認している。こ の種構成は他の温帯地域(暖温帯，冷温帯寡雪地)と 類似していることから (Kanda et al, 2005(Kanda et al, , 小池ほか， 2006a(Kanda et al, , 2006bKoike et al, 2013Koike et al, , 2014 (Estrada et al, 1998(Estrada et al, , 1999Feer & Hingrat, 2005…”