First evidence of bryophyte diaspores in the plumage of transequatorial migrant birds

PeerJ. 2014 Jun 12;2:e424. doi: 10.7717/peerj.424. eCollection 2014.

Abstract

Correlations between transequatorial migratory bird routes and bipolar biogeographic disjunctions in bryophytes suggest that disjunctions between northern and southern high latitude regions may result from bird-mediated dispersal; supporting evidence is, however, exclusively circumstantial. Birds disperse plant units (diaspores) internally via ingestion (endozoochory) or externally by the attachment of diaspores to the body (ectozoochory). Endozoochory is known to be the primary means of bird-mediated dispersal for seeds and invertebrates at local, regional, and continental scales. Data supporting the role of bird-mediated endozoochory or ectozoochory in the long distance dispersal of bryophytes remain sparse, however, despite the large number of bryophytes displaying bipolar disjunctions. To determine if transequatorial migrant shorebirds may play a role in the ectozoochory of bryophyte diaspores, we developed a method for screening feathers of wild birds. We provide the first evidence of microscopic bryophyte diaspores, as well as those from non-bryophyte lineages, embedded in the plumage of long distance transequatorial migrant birds captured in their arctic breeding grounds. The number of diaspores recovered suggests that entire migratory populations may be departing their northern breeding grounds laden with potentially viable plant parts and that they could thereby play significant roles in bipolar range expansions of lineages previously ignored in the migrant bird dispersal literature.

Keywords: Bipolar; Bryophyte; Diaspore; Ectozoochory; Endozoochory; Long-distance dispersal; Shorebirds; Sporic; Transequatorial.

Grant support

Funding for this project comes from the University of Connecticut Katie Bu Memorial Fund awarded to EQ, Switzer Environmental Fellowship awarded to LRL, and National Science Foundation grants DEB 1311405 and 1212505 to LRL and BG, respectively. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.