Birds are known to act as potential vectors for the exogenous dispersal of bryophyte diaspores. Given the totipotency of vegetative tissue of many bryophytes, birds could possibly also contribute to endozoochorous bryophyte dispersal. Fecal samples of Upland Goose (Chloephaga picta) and White-bellied Seedsnipe (Attagis malouinus) contain many bryophyte fragments (Russo et al.2018). Although one of these generated new growth, the general viability of diaspores following passage through the bird intestinal track remains ambiguous. We tested this hypothesis for bryophytes consumed by these same herbivorous birds in sub-Antarctic Chile. We opportunistically collected droppings of both species from six sites in alpine and lowland habitats of Navarino Island, screened six samples for bryophyte fragments (one from each site), and cultured 343 fragments in containers containing forest, turf, or mixed soil, and in vitro (Gamborg medium). We also sampled three wild populations of local mosses in these habitats (i.e., Conostomum sp., Syntrichia sp., Polytrichum sp.) and tested their totipotency and regeneration ability on the same substrates. Twenty-one samples containing fragments from feces and fifteen wild moss samples were placed in a growth chamber.
Results/Conclusions
After about 3 months (91 days), four of nine (44%) of White-bellied Seedsnipe samples, eight of 12 (67%) of Upland Goose samples, and 12 of 15 (80%) of the wild moss samples produced new growth based on the occurrence of “light” green shoots. Of these, nine developed on forest soil, five on turf soil, and seven on mixed soil. The three species of fragmented wild mosses inoculated in the solid Gamborg medium showed vegetative growth. On the contrary, by this method, no growth was observed on any of the six samples tested from both bird species. The results shown by the Gamborg medium suggest that the three mosses sampled are totipotent, a necessary condition for effective endozoochory. The former observations reveal that furthermore, moss diaspores may remain viable following the passage through the intestinal track of both birds, and are capable of regeneration. Consequently, sub-Antarctic birds may play a passive and critical role in the dispersal of bryophytes, as birds are more likely to defecate in like habitat conditions, thereby enabling bryophytes to effectively propagate within a generally suitable habitat and where they are unlikely to be carried by wind or rain.