Breeding biology of the Sayaca Tanager (Thraupis sayaca) in southeast Brazil

• Published in: Journal of natural history 2019-10, Vol.53 (39-40), p.2397-2412
• Main Authors: Batisteli, A. F., da Silva Neto, E. N., Soares, T. P., Pizo, M. A., Sarmento, H.
• Format: Article
• Language: English
• Subjects: Animal behavior; Anthropogenic factors; Biology; Body height; Breeding seasons; Clutch size; Eggs; Females; Incubation; Introduced species; Males; Neotropical; nesting behaviour; Nests; parental care; Provisioning; Sanitation; Thraupidae; Thraupis sayaca; Tropical forests; urban bird
• ISSN: 0022-2933; 1464-5262
• DOI: 10.1080/00222933.2019.1704462

Thraupis is a genus of the American endemic Thraupidae (subfamily Thraupinae), comprising seven species that inhabit tropical forests to urban centres. The Sayaca Tanager (Thraupis sayaca) is a disturbance-tolerant species of high representativeness in plant-frugivore networks, but information on its breeding biology is scarce and often restricted to non-systematic surveys. We studied the breeding biology of the T. sayaca, following 39 active nests in a periurban area of southeast Brazil during two breeding seasons (2017/2018, 2018/2019). The breeding season ranged from early September to middle December, and the nests were placed in native and exotic plants and human buildings (nest height above ground: 3.35 ± 1.73 m, mean ± SD). Only females incubated and brooded, but both adults built the nests, fed the nestlings, and removed their faecal sacs. Clutch size was 2.86 ± 0.38 eggs and nest attentiveness was 71.2%. The incubation and nestling periods were, respectively, 13.4 and 17.4 days. Males and females did not differ on nestling provisioning and nest sanitation rates. Nestling provisioning (13.35 ± 6.25 trips/hour) increased with nestling age, while mean brooding time was 37.2% and decreased with nestling age. Apparent nest success was 38.7%, and nest survival according to the Mayfield method was 27.2%. Five nests (20.8%) were parasitised by the Shiny cowbird (Molothrus bonariensis), and we recorded five events of nest-site reuse. We concluded that the most remarkable breeding traits of T. sayaca in comparison with close-related tanagers are the use of anthropogenic nest sites, the higher clutch size and number of feeding trips, and the longer nestling period.