Forest passerines as a novel dispersal vector of viable bryophyte propagules

Abstract

Animal dispersal influences the community structure and diversity of a wide variety of plant taxa, yet the potential effects of animal dispersal in bryophytes (hornworts, liverworts, and mosses) is poorly understood. In many communities, birds use bryophyte-abundant niche space for foraging and gathering nest material, suggesting that birds may play a role in bryophyte dispersal. As highly motile animals with long migratory routes, birds potentially provide a means for both local and long-distance bryophyte dispersal in a manner that differs greatly from passive, aerial spore dispersal. To examine this phenomenon, we collected and germinated bryophyte propagules from the legs, feet and tails of 224 birds from 34 species within a temperate forest community. In total we found 1512 spores, and were able to germinate 242 bryophyte propagules. In addition, we provide evidence that topical (externally-carried) spore load varies by bird species and behaviour. Tail feather spore abundance is highest in bark and foliage gleaning species and is positively correlated with tarsal length. Together, these data suggest that a variety of forest birds exhibit the potential to act as dispersal vectors for bryophyte propagules, including an abundance of spores, and that understanding the effects of animal behaviour on bryophyte dispersal will be key to further understanding this interaction.

The Fate of Bryophyte Sporophytes—Phenology and Vectors of Buxbaumia viridis in the Kalkalpen National Park, Austria

“…The epizoochory of bryophyte propagules by birds has been convincingly presented by Chmielewski and Eppley [ 26 ]. They suggest the spread of bryophytes both locally and over long distances by birds, based on the observation of bryophyte spores on tail feathers and legs.…”

“…In general, the spread of spores by birds is suggested to be a by-product of animal behavior, rather than the result of close co-evolution [ 26 ]. Our observations are consistent with this hypothesis, as birds searched the log or the soil around the clusters of sporophytes, but they did not specifically respond to the sporophytes.…”

“…Data on other vectors than the wind are very rare in general for bryophyte spores [ 26 , 27 ], and they are completely missing for Buxbaumia viridis . Animals should be considered.…”

“…Animals should be considered. Studies on the epizoochory of bryophytes are scarce [ 26 ]. Most studies on the endozoochory of bryophyte spores so far focused on slugs [ 28 , 29 ].…”

An attempt to create air sacs in spores? On the unusual spore structure in moss Encalypta longicollis

“…Moss spores are anemochorous with the only two known exceptions for zoochory by Splachnaceae (Koponen, 1990;Marino, 2009;McCuaig et al, 2015) and Schistostega (Ignatov & Ignatova, 2001). Despite recent literature reported a number of cases of moss spore carriage by birds (Lewis et al, 2014;Chmielewski & Eppley, 2019) and small mammals (Barbé et al, 2016), nothing is still known about the efficiency of this way of dispersal. We may just hypothesize that it is highly underestimated, judging from the distributional patterns of some species.…”