Gastrointestinal passage time of seeds ingested by captive Japanese martens Martes melampus

Abstract

The time it takes for ingested seeds to pass through the gut of animals is an important aspect of endozoochorous seed dispersal because it influences seed dispersal distance. Variations in the physical characteristics of seeds, such as their weight, volume, and specific gravity, can affect their movement through the gastrointestinal system of a given animal. We conducted feeding experiments with captive Japanese martens, Martes melampus (n=4), at Toyama Municipal Family Park Zoo, central Japan to examine the effects of the physical characteristics of seeds on their passage times. The mean (±SD) transit time, mean retention time, and time of last appearance of four different types of commercial seeds were 2.6±0.3 h (range 0.6-5.4), 9.7±1.1 h (3.8-17.3), and 23.8±3.1 h (12.2-51.8), respectively. All of these values are greater than those found during previous experiments conducted with mustelids. Similar to previous studies, however, none of these passage time variables was correlated with the physical characteristics of seeds. Our results thus indicate that martens disperse seeds of different plant species, whose size, volume, and specific gravity all fall within the range of those used in the present study, from parent plants at similar distances.

Effects of endozoochory and diploendozoochory by captive wild mammals on Juniperus deppeana seeds

“…TA B L E 2 Average SEM measurements of the thickness (x ± SD) of the seed testas of Juniperus deppeana from each of the mammals (endozoochory and diploendozoochory) compared to the control group (canopy) and the retention time for each animal species. The gray fox and the coati, had short retention times to disperse the seeds in a maximum time of 21 h while, in other studies with mediumsized mammals, retention times of no more than 10 h were obtained (Tsuji et al, 2011;Varela & Bucher, 2006;Zhou et al, 2008). In turn, Graae et al (2004) determined that the arctic fox presents an average seed retention of 44-48 h, which is a much longer period than our results suggest.…”

Gut retention time in captive brown bears Ursus arctos

“…because of depredation incidents), the GRT also defines the time frame during which depredated foods are expected to be found in the digestive tract of destroyed animals. The GRT has been studied for several aquatic and terrestrial carnivores (Edwards et al 2001, Hall‐Aspland et al 2011), as well as for omnivores (Tsuji et al 2011). In bears, Ursidae, the GRT has been studied in omnivores with mainly a vegetative diet (giant pandas Ailuropoda melanoleuca ; Dierenfeld et al 1982), almost exclusively carnivores (polar bears Ursus maritimus ; Best 1985), and omnivores with relatively large variation in their diet (Asiatic black bears Ursus thibetanus ; Koike et al 2010, and brown bears Ursus arctos ; Pritchard & Robbins 1990).…”

Do Roads Alter the Trophic Behavior of the Mesocarnivore Community Living Close to Them?

“…The study design does not allow knowing the movement patterns of individuals or knowing which individuals defecated at any point of the study area. However, given that the mean gut retention time of mid-sized carnivores is 7-25 h [62][63][64], were individuals to range systematically through areas more and less distant from the road within their home ranges (of 300-500 ha, according to species, [65]) their scats would include a mixture of material ingested throughout their territories. In such circumstances, the contents of their scats would not show any clear spatial pattern (as seems to be the case of the fox) and would not reflect the higher small mammal abundance found nearest the road (seen in the other three species).…”