Spatio-temporal distribution of eight species of herons (Ardeidae) during the breeding season in Isla Pajaros, Oaxaca-Chiapas, Mexico

Herons that breed in colonies have similar ecological requirements and intensify their interspecific relationships. However, these species can coexist by segregating temporally and spatially. In this study, the number of nests from eight species of herons (Ardea alba, Egretta thula, E. caerulea, E. tricolor, E. rufescens, Bubulcus ibis, Nycticorax nycticorax, and Cochlearius cochlearius) was estimated during the breeding season from March to August 2018 in Isla Pajaros, Mar Muerto Lagoon, Oaxaca-Chiapas, Mexico. Likewise, the number of breeding pairs, the temporal, and the spatial pattern of reproduction by species were estimated, and the nest sites were described. Nest were counted in 96 plots and eight environmental variables were measured. A total of 1018 nests were recorded, with B. ibis having the highest number of breeding pairs (299), followed by E. tricolor (213) and E. thula (142). The least abundant species were C. cochlearius (35) and E. caerulea (33). Nest distribution on the island was heterogeneous and varied spatial and temporally among plots as did species composition and nest abundance per plot (P < 0.001). A vertical distribution in the nest construction of at least three species was recorded on the island, while the four egrets of similar size (Egretta thula, E. caerulea, E. tricolor, and Bubulcus ibis) nested together in middle parts of the mangrove. Clusters among species and vegetation characteristics were recorded. The spatial and temporal distribution patterns of these species allow us to understand the use of a common resource during reproduction.