Affordable high-throughput sequencing enables researchers to quickly characterize fungal communities that were heretofore hidden in plain sight. It is a given that birds have their own fungal communities, but what is the nature of these communities, how do they differ among bird species or guilds and how do they differ across habitats? In southern Costa Rica, as elsewhere in the tropics, agriculture is interspersed with forest. Habitat use by neotropical birds has been well-studied, including the effects of forest clearing for agriculture on bird communities. Bird species richness and activity have been shown to be high in coffee fields, especially in regions with extensive forest, and many bird species move between coffee and forest on the landscape. To begin to characterize the external fungal communities of neotropical birds across habitats, we mistnetted birds at four sites near San Vito, Costa Rica: a secondary forest and botanic garden at Las Cruces Biological Station and two nearby coffee farms. Birds were swabbed externally for DNA and released. DNA was extracted from swabs, pooled by bird species per site, amplified with fungal-specific ITS2 primers and sequenced by Illumina Miseq. Phylotypes were processed using the PIPITS pipeline, matched to closest known sequence using the Warcup database, and sorted to approximate guild with FUNGuild.
Results/Conclusions
In four days of sampling, we obtained fungal DNA from 38 bird species. The majority of the fungal DNA sequences detected (57%) could not be identified. Of those that could, about half appeared to be saprotrophs, one third belonged to plant-associated fungi, and fewer than one-fifth belonged to known animal pathogens. The amount of fungal DNA per individual did not differ across bird taxa or sites. However, fungal richness was highest in birds captured on coffee farms and lowest on birds captured in secondary forest. Birds which forage on the ground carried the most diverse fungal communities while hummingbirds exhibited the lowest fungal species richness. The composition of the fungal community also differed among bird taxa and across the sites. Beta diversity was highest at the forest site and lowest at the coffee farms and appeared to be driven by differences in fungal community composition among hummingbird species. These preliminary results suggest that which bird species move through or across habitats and how they use resources has consequences for fungal community composition and dispersal across land use types.