Conclusions
We confirmed the hypothesis that fragmented bryophyte gametophytes retrieved from the feces of herbivorous birds could regenerate in laboratory conditions. Consequently, our research shows that it is plausible for fragments to be dispersed through endozoochory by these herbivorous birds in the sub-Antarctic, possibly further aiding bryophytes in this region to disperse beyond wind or rain, and increasing their capability to reach specific habitat types (Figure 2). As both bird species are robust fliers, altitudinal migrants for short distances and latitudinal migrants for long distances, their role as dispersers might not only occur locally, but also at a broader scale. This is especially important as with warming conditions, organisms such as mosses would have to move to higher altitudes or latitudes to maintain viable populations. By serving as dispersal vectors, birds would be able to aid in this process in short time scales in the vertical and horizontal axes of the landscape. This process is especially critical in maintaining the viability of bryophytes in Navarino Island, which contains an “ecosystem of highest ecological importance” (Goffinet et al., 2012) and holds many endemic species (Méndez et al., 2013), and just as critical globally where bryophytes are also being affected by changes to their ecosystems.
Sub-Antarctic birds may play a passive, but likely critical role in the dispersal of bryophytes, as birds are more likely to defecate in like habitat conditions where they graze (J. Jiménez, 2019, pers. comm.). Thus, potentially enabling bryophytes to effectively propagate within a generally suitable habitat and in locations where they are unlikely to be established by wind or rain, but are accessible to birds. However, further research needs to be done to test bryophyte dispersal through endozoochory and the role of birds in this process. To progress along this line of research, we suggest a larger sample size and replication, more substrate treatments, as bryophyte fragments might respond variably to distinct types of soil, and conducting DNA sequencing of the bryophyte fragments found in the fecal samples to identify the bryophyte species before culturing them. Finally, there is the need to reproduce these results under field conditions, so we can understand the relevance of this type of zoochory in bryophyte dispersal at these high-latitude landscapes.