Study site and sample collection
Sampling and data collection were performed from March to May 2019 and April to May 2020 in artificial nests relocated at the Tiputini Biodiversity Station (TBS) (037’05”S, 7610’19”W, 190-270 m a.s.l) situated in the Yasuni Biosphere Reserve in the Orellana province of Ecuador. After the incubation period (3 months) we determined symptoms of fungal infections by visual inspection. Eggs were cataloged as symptomatic eggs when covered with unusual colored spots (green, pink, greyish) and with a non-uniform shape (Figure 1a), and eggs without these traces were cataloged as asymptomatic. In 2019, we sampled inner eggshells of 68 eggs (29 asymptomatic, 39 symptomatic) using a sterile swab. In 2020, hatchability data of 680 eggs (394 asymptomatic eggs, 286 symptomatic) from 23 different nests was collected. See supplementary information for detailed information on sampling design and data collection.