TEMPORAL DYNAMICS IN PANTANAL HUMMINGBIRD ASSEMBLAGES IS TRIGGERED BY FLOOD PULSE

Abstract

Hummingbirds (Trochilidae) are highly specialized New World birds that depend on nectar as their major food source. In response to seasonal food limita>ons, many trochilids develop dispersal and long-distance migra>on pa'erns, but these pa'erns are understudied for many con>nental South American species. In this study, conducted in the Brazilian Pantanal, we inves>gated the movement pa'erns of hummingbirds in a highly variable environment, where an annual flood pulse leads to four dis>nc>ve seasonal periods (high water, receding water, dry period, and rising water). Our objec>ve was to verify how these four periods affected the hummingbird community according to habitat occupa>on 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 inunda>on periods (2014–2016). Data were collected using mist net sampling. Two migrant and seven resident species were iden>fied. 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.