Biologia reprodutiva de Pyrocephalus rubinus (aves: Tyrannidae) no sul do Brasil

Abstract

We studied the breeding biology of Vermilion Flycatcher (Pyrocephalus rubinus), in southern Brazil, Pampa Biome. Although there is publications available about the breeding of P. rubinus, some basic parameters remain unknown. We collect data during the breeding season (October-January 2013-2014) in Parque Estadual do Espinilho (PEE) (30° 11' S 57° 30' O), situated in the city of Barra do Quaraí, Rio Grande do Sul. We monitored 65 nests and evaluated aspects related to reproduction of the species, such as territoriality, the nesting chronology, features of nests, eggs and nestlings, clutch size, incubation, hatching rate, parental care, reproductive success and predation. Breeding starts from the earlier October, peaks in later October and lasts until early January. The average size of reproductive territories was 0.013 ± 0.5 ha (20). There is no distinction in the nesting territories selection associated with phytosociology, all nests were built on the same support plant (Prosopis affinis Spreng). Nests are basket-shaped and built only by female in 5-7 days, at an average height 2.21 m above the ground. The clutch size is 2.86 eggs. Incubation, which is perfomed only by female, lasts 13-14 days and is synchronic. The hatching rate was 83%. Nestlings remain in the nest for 12-14 days. In most nests the nestlings are fed by male and female (biparental care). The frequency visits to the nest for feeding differed according to the age of nestlings, with a higher visits rate by the male in the first days of life of the nestlings and by the female in the following days. The apparent success of the nests was 17%, while the MARK success was 9%. The model tested for nest survival includes time-specific factors (age nest) and nest site characteristics (height), the effect of these variables explains the percentage of survival. The daily survival rates (DSR) decrease along the nesting cycle, falling off sharply with the increasing of nest height to the ground. Only 11 of the 65 nests were successful (16.9%), while 54 were unsuccessful (83%), among abandoned (7.40%) and preyed (92.5%). Predation was the main cause of clutches loss, affecting 76% of unsuccessful nests. No predation event was recorded, but rather agonistic behavior of P. rubinus was observed relative to other birds.