Marasmius, Yellow-olive Flycatcher, Bird nest materials, Belize


Black Marasmius fungal fibers have been frequently observed in neotropical bird nests. We tested to determine if superior tensile strength and temperature moderation contributes to why these fibers are preferred by some species over other available nesting materials. Marasmius fibers from nests of Yellow-olive Flycatchers (Tolmomyias sulphurescens) were compared to grass fibers from a Yellow-tailed Oriole (Icterus mesomelas) nest from the same area in Belize, Central America. We measured tensile strengths by a universal strength tester which stretched the fibers to their breaking point. We also used HOBO data loggers to compare the temperature differential between ambient environment and nest interiors in black fiber nests versus the grass fiber nest. Both hypotheses were rejected, suggesting other factors may be operative in the preference of these nest material.