Effects of Density on Spatial Aggregation and Habitat Associations of the Glass FrogEspadarana (Centrolene) prosoblepon

Social behaviors often are context dependent; behaviors at high density may change or disappear at lower population densities. We analyzed spatial dispersion patterns and habitat associations at high and low population densities of male Espadarana (Centrolene) prosoblepon that declined following the invasion of a pathogenic fungus, Batrachochytrium dendrobatidis (Bd). We mapped the spatial location of male frogs on four permanent 200-m stream transects over 4 pre- and 7 postdecline yr. We calculated distances between nearest neighbors and between hot spots—defined as areas of high male density—and compared habitat associations of frogs at high and low densities. Average predecline density across transects was 0.034 ± 0.02 males m−1 (mean ± SE) and dropped to 0.019 ± 0.02 males m−1 postdecline. Nearest neighbor and between cluster distances did not change significantly between pre- and post-decline yrs. Nine of 21 hot spots persisted in the same location across 12 yrs, whereas 8 hot spots disappea...