Reproduction of Blue-black Grassquits in central Brazil

Abstract

During the reproductive season Blue-black grassquit (Volatinia jacarina) males are found in clusters, wherein they exhibit a distinctive display that consists of repeated, vertical leaps while simultaneously producing a brief vocalization. The main objective of this study was to describe details of the species' reproductive behavior in a "Cerrado" area of central Brazil and compare these data with some studies carried out in other areas. The data obtained concerning different aspects of nesting, laying and hatching were generally similar to those obtained in previous studies in other areas. However, we found that the typical clutch size of two eggs per nest is lower, and egg and nestling mortality rates higher in our area than what has been reported elsewhere. Our results suggest that males differ in time expended with different activities according to their reproductive condition and also provide extensive parental care. We found that display execution rates peak in the early morning and in the late afternoon and are higher in the middle of the breeding season. We also found that there is an inverse relation between the height of the display leap and the height of the perch. Reprodução do tiziu no Brasil central Resumo Durante a estação reprodutiva, machos de tiziu (Volatinia jacarina) são encontrados agregados e apresentam uma exi-bição bastante conspícua, que consiste de saltos verticais associados a uma curta vocalização. Através de observações realizadas em uma área de Cerrado na região do Brasil central, este trabalho teve como objetivos detalhar alguns as-pectos da biologia reprodutiva de V. jacarina e comparar tais dados com os poucos trabalhos existentes sobre a espécie. Os dados obtidos neste estudo com relação aos diferentes aspectos da nidificação, postura e eclosão dos ovos se mos-traram semelhantes, em geral, àqueles encontrados em estudos anteriores, diferindo apenas com relação ao número de ovos por ninho (a maioria dos ninhos com apenas dois ovos) e às taxas de predação, que se mostraram mais elevadas. Os dados mostram ainda que machos variam com relação ao gasto de tempo com diferentes atividades de acordo com a condição reprodutiva e que os mesmos investem parentalmente. Foram encontradas ainda, que as taxas de execução de exibição são mais elevadas no início da manhã e no final da tarde, assim como também tem um pico no meio da estação reprodutiva. Encontramos também uma relação inversa entre a altura do salto da exibição e a altura do poleiro.

Reproductive behavior of the Red-crested Finch Coryphospingus cucullatus (Aves: Thraupidae) in southeastern Brazil

“…Incubation performed only by the females and the less intensive participation of males in nestling provisioning has also been observed in the Grey-headed Tanager (skuTcH 1954). This pattern is different from that found for the Blue-black Grassquit, in which males share both incubation and nestling provisioning with the females (caRvalHo et al 2007). Notably, incubating females of the Red-crested Finch were reluctant to leave the nest when the observer approached it, allowing herself to be touched in the nest.…”

“…First, nests of the Blue-black Grassquit Volatinia jacarina (Linnaeus, 1766) and the Grey-headed Tanager Eucometis penicillata (Spix, 1825) are in the shape of cups and are built mostly of rootlets. Although the nest walls are compact, they are so thin that eggs can be seen through them, and they lack any type of adornment (skuTcH 1954, caRvalHo et al 2007 (Swainson, 1838)), and the spots and blotches are often brownish and concentrated in the larger pole (Silver-beaked Tanager, Black-goggled Tanager, Ruby-crowned Tanager), or they can form a crown near the larger pole (Scarlet-rumped Tanager, Black-and-white Tanager) (euleR 1900, skuTcH 1950, 1954, PinTo 1953, HaveRscHmidT 1956, gReeney et al 2006, caRvalHo et al 2007, ingels 2007, gReeney & sHeldon 2008. This is another important distinctive characteristic of Coryphospingus, as these are the only tanagers that have completely white eggs.…”

Striped-tailed Yellow-finch nesting success in abandoned mining pits from central Brazilian cerrado

“…However, our estimates of nest survival (26%) are in the range of those found for other emberizids in the cerrado region, both in natural habitats: Coal-crested Finch Charitospiza eucosma (20%; Diniz et al 2013), and in altered habitats: Blue-black Grassquits Volatinia jacarina (24%; Aguilar et al 2008), and Double-collared Seedeater Sporophila caerulescens (36%; Francisco 2006). Stripe-tailed Yellow-finch's nest success rates, nevertheless, were considerably lower than the observed for the Grassland Yellow-Finch Sicalis luteola breeding in Brachiaria-dominated pastures (47%; Freitas and Francisco 2012), and significantly higher than the observed for Blue-black Grassquits, also breeding in an altered habitat (>5%; Carvalho et al 2007). Such cases, however, apparently represent extreme values due to their discrepancies comparing to other studies in the cerrado region.…”

Social environment affects testosterone level in captive male blue–black grassquits

“…The males defend small territories during the breeding season, presenting a conspicuous, multi-modal display of repeated jumps from elevated perches, which are powered by wing-flapping, while exhibiting a white under-wing patch and vocalizing. Nests are built by each pair inside the male's territory and both male and female present parental care (Carvalho et al, 2007). The blue-black grassquit is socially monogamous (Almeida and Macedo, 2001), and recent studies have found a high rate of extra-pair fertilization (60% of chicks) for our study population (Carvalho et al, 2006).…”

“…In central Brazil, where this study was conducted, these birds are migratory, arriving in the area each year starting in October, breeding from about November to April, after which they depart (Carvalho et al, 2007). Adult males exhibit plumage that varies from glossy black, during the breeding season, to black with brown patches, outside the breeding season (Aguilar et al, 2008), while females and juveniles have brown, inconspicuous plumage.…”