SEEDEATERS AND SEEDS AT A TECOMA SAVANNA IN THE SOUTHERN PANTANAL, BRAZIL

Abstract

Seedeaters (Sporophila spp.) comprise a rich Neotropical bird group of seed consumers common in open habitats. In this study, we documented the feeding habits of seedeaters and seed production at a Tecoma savanna (dominated by Tabebuia aurea) in southern Pantanal, Brazil. We also analyzed the relationship between seed offer (abundance, richness, and diversity) and the number of seedeaters foraging across seasons. Six species (Sporophila angolensis, S. caerulescens, S. collaris S. hypoxantha, S.leucoptera, and S. lineola) occurred in the savanna, mainly in the height of the wet season, when seed production increased abruptly, attracting seedeaters. Seedeaters used 14 of 16 grass species that produced seeds. Indeed, the number of foraging seedeaters paralleled the abundance and diversity of seeds, and the number of species consumed. During much of the dry season, when seeds were not produced, the few remaining seedeaters mostly consumed arthropods and flowers. The diet of seedeaters ranged from mostly seeds (S. angolensis) to a moderate proportion of flowers and arthropods (S. leucoptera). The offer of a rich set of seeds attractive to seedeaters indicates that the Tecoma savanna is a seasonally important habitat for these birds. Of concern, large areas of native grasses in the Pantanal have recently been transformed into exotic pastures, and extensive fires have become common. Thus, conservation of this singular area is important for seedeaters, which move over wide areas searching for an abundant and diverse seed supply.