The breeding biology, nest success, habitat and behavior of the endangered Saffron-cowled Blackbird, Xanthopsar flavus (Aves: Icteridae), at an Important Bird Area (IBA) in Rio Grande do Sul, Brazil

Luciane R Da Silva Mohr,Alexsandro R Mohr,Vanda S Da Silva Fonseca,Eduardo Périco

doi:10.3897/zoologia.34.e20783

Abstract

ABSTRACT The Saffron-cowled Blackbird, Xanthopsar flavus (Gmelin, 1788), is a globally vulnerable icterid endemic to grasslands and open areas, and a priority species for research and conservation programs. This contribution provides information on the population size, habitat, behavior, breeding biology and nest success of X. flavus in two conservation units (CUs) in Viamao, state of Rio Grande do Sul, Brazil: the Environmental Protection Area Banhado Grande, and the Wildlife Refuge Banhado dos Pachecos, classified as an “Important Bird Area”. Searches for X. flavus were carried out mainly in open areas, the type of habitat favored by the species. Outside the breeding season individual behavior was recorded by the ad libitum method; during the breeding season, selected X. flavus pairs were observed following the sequence sampling method. The research areas were visited once a month, totaling approximately 530 hours of observations (September 2014 to June 2016) over 84 days, which included two breeding seasons. The species was observed across all months (not necessarily within the same year) and several X. flavus flocks were encountered, some with more than one hundred individuals (range = 2-137). Additionally, the behavior and feeding aspects, habitat use and breeding information on X. flavus were recorded. Two breeding colonies were found, and eleven nests were monitored. The estimated nesting success was 10% in Colony 1, but zero in Colony 2, where all eggs and nestlings were predated. Saffron-cowled Blackbirds were recorded in mixed flocks, mostly with Pseudoleistes guirahuro (Vieillot, 1819), P. virescens (Vieillot, 1819) and Xolmis dominicanus (Vieillot, 1823), the last also a globally endangered species. The collected information highlights the importance of CUs for the maintenance of X. flavus populations in the region. Maintenance of proper areas for feeding and breeding is necessary and urgent. Information from current research is being employed in the management plan of the Wildlife Refuge Banhado dos Pachecos in which X. flavus is one of the conservation target-species.

Highlights

The Saffron-Cowled Blackbird, Xanthopsar flavus (Gmelin, 1788), is an endemic species of the grasslands of southern South America (Collar et al 1992)
The current study provides data on the size of the Saffron-Cowled Blackbird population, habitat, behavior, breeding biology and nest success from an Important Bird Area (IBA) and its immediate vicinity, on the internal coastal plain of Rio Grande do Sul, Brazil
The Wildlife Refuge Banhado dos Pachecos (WRBP) is classified as an “Important Bird Area” (IBA), highly relevant for bird conservation, for species that depend on dense marshes and wet grasslands, including endangered species (Bencke et al 2006)

Summary

Introduction

The Saffron-Cowled Blackbird, Xanthopsar flavus (Gmelin, 1788), is an endemic species of the grasslands of southern South America (Collar et al 1992). The species is of high priority for conservation and research (Stotz et al 1996, Fontana et al 2013) This bird depends on heterogeneous areas of natural grassland, and uses different habitats for feeding and nesting (Fonseca et al 2004, Fraga 2005, Azpiroz et al 2012). It is currently listed as vulnerable at the regional, national and global levels (State Decree 51.797/2014, ICMBio/2014, IUCN 2016), largely due to the destruction and degradation of its habitat, and the consequent disruption of its biological cycle. The world population of the species is estimated at 10,000 individuals, at the most (Birdlife International 2016)

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