OBSERVATIONS ON PARENTAL CARE OF THE MASKED WATER-TYRANT (FLUVICOLA NENGETA) IN RIO DE JANEIRO, BRAZIL

The Masked Water-Tyrant (Fluvicola nengeta) belongs to the family Tyrannidae and inhabits locations close to bodies of water and urban environments. This work aims at describing basic aspects of the breeding biology, specifically the timing of the breeding season and parental care behavior through observations of nestling feeding frequency, identification of food items and nest defense. The study was conducted at Universidade Federal Rural do Rio de Janeiro, Brazil, between October 2012 and June 2014. Fluvicola nengeta did not show a defined breeding season, reproducing throughout the year. During 33 hours of observations at 14 nests were recorded 518 feeding records, with an average of 16.7 (SD = 1.85) food items brought to the nest per hour. This feeding rate was high, compared to that of other Tyrannidae, and may be connected to the low levels of nest predation in the study area. The feeding rate increased throughout the day peaking in the middle of the day, declining by the end of afternoon. Both parents participated in feeding and defending the offspring. Food items brought to the nest included: Odonata (N = 3), Lepidoptera (N = 3), Coleoptera (N = 1), Hymenoptera - Formicidae (N = 1), and Arachnida (N = 1). The parents defended its nests against 22 species of birds and this behavior was classified in two categories: display (52%) where the intruder was simply warned using visual warning behaviors and persecution (48%), which resulted in chases. Displays were generally carried out by both pair members while persecutions usually involved only one individual, the other remaining close to the nest.