TEMPORAL DYNAMICS IN PANTANAL HUMMINGBIRD ASSEMBLAGES IS TRIGGERED BY FLOOD PULSE

Abstract

Abstract ∙ Hummingbirds (Trochilidae) are highly specialized New World birds that depend on nectar as their major food source. In response to seasonal food limitations, many trochilids develop dispersal and long-distance migration patterns, but these patterns are understudied for many continental South American species. In this study, conducted in the Brazilian Pantanal, we investigated the movement patterns of hummingbirds in a highly variable environment, where an annual flood pulse leads to four distinctive seasonal periods (high water, receding water, dry period, and rising water). Our objective was to verify how these four periods affected the hummingbird community according to habitat occupation in savannas or forests. This study was conducted in the northeastern Pantanal of Mato Grosso, Brazil (16° 39'S, 56°47'W, 119–131 m a.s.l.), covering two annual inundation periods (2014–2016). Data were collected using mist net sampling. Two migrant and seven resident species were identified. The results indicated significant differences in hummingbird species richness and abundance between habitats; savanna habitats were the richest habitats during rainy seasons (rising and high water). Higher hummingbird abundance in these seasonal periods was seemingly related to higher food availability since these seasons corresponded to the main flowering period of ornithophilous plants and other angiosperms.