Frugivory and seed dispersal by carnivores in the Rhodopi mountains of northern Greece

Abstract

The frugivory and seed dispersal by carnivores were studied using a combination of vegetation surveys, fruit production counts and analysis of faeces distribution and content. The study site is situated close to the Greek-Bulgarian border within a protected area. The habitat comprises of a mixed forest of beech, pine, oak and spruce which is occasionally interrupted by patches of fruiting trees. Faecal samples were collected on five permanent transects which were sampled monthly between May and October of 1993 and 1994.Fruiting plant density was found to be slightly higher in the forest than along forest roads, however the species diversity was much higher on the latter. In some cases, immature fruiting plants were found on transects with no mature plants in the vicinity. Availability of ripe fruit was found to increase steadily between May and September. There was a significant difference between the numbers of faeces deposited by the carnivores, with fox being the most numerous, followed by marten, bear and wolf. There was spatial and temporal variation in the number of faeces deposited. Nevertheless, there was no variation between different altitudinal zones. Martens were found to defecate more often on stones when compared with the other carnivores. The analysis of fruit consumption revealed that bears were the most frugivorous carnivores followed by foxes, wolves and martens on the basis of frequency of consumption. The temporal availability of each ripe fruit species coincided with their consumption by the carnivores in most of the cases. A number of seed species were deposited at altitudes where the plants do not normally grow. Foxes dispersed the highest numbers of seeds in the study area and bears were second as they deposited large-size faeces which contained many seeds. Of the dispersed seeds, those of Rubus sp., Rosa sp. and Fragaria vesca were deposited in the highest numbers. Only a small number fraction of seeds were damaged through handling by carnivores.