História natural de Sporophila melanogaster (Pelzeln 1870) (Aves: Emberizidae) com ênfase em sua biologia reprodutiva

• Ano de defesa: 2011
• Autor(a) principal: Rovedder, Cristiano Eidt
• Orientador(a): Fontana, Carla Suertegaray
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: BIOLOGIA; ZOOLOGIA; ORNITOLOGIA; PÁSSAROS - RIO GRANDE DO SUL; AVES - HÁBITOS E CONDUTA
• Link de acesso: http://hdl.handle.net/10923/5358

The Black-bellied Seedeater, Sporophila melanogaster (Pelzeln 1870) (Aves: Emberizidae) is a species endemic to Brazil. It is a migratory species occurring from April to September in the tropical grasslands of the central region of the country, in the Cerrado biome and from November to March in the high-altitude grasslands of the southern portion of the Mata Atlântica biome, southeast of Santa Catarina (SC) and northeastern Rio Grande do Sul (RS), where it breeds. Their biology and ecology is poorly known, despite being threatened with extinction regionally and nationally. In the breeding seasons of 2007/2008, 2008/2009 and 2009/2010, we studied its natural history, with emphasis on its breeding biology. We searched for nests monitored them in three areas of wet grasslands of RS and SC. Males place territories in marshes or wet fields, with in an average 0. 27 ± 0032 ha. Floristic composition of 20 territories samples with nest and 20 non-territories samples (total 800m2) accounting for 97 most abundant plant species. Territories were choosen based on composition and structure of the vegetation in specific habitat portions. Records for diet resulted in 24 seeds of plant species consumed by adults and chicks, belonging to the families Poaceae, Cyperaceae and Juncaceae. Its nest is shaped-like a basket down an open, mainly built in small shrubs with the predominant species Ludwigia sericea (Onagraceae), at a height of 31. 5 ± 10. 8 cm. Lay two eggs, rarely three, and both the nest construction and incubation are performed exclusively by females. The construction lasts 5. 2 days (min = 3, max = 8) and incubation 12. 7 (min = 12, max = 13). The nestlings leave the nest at 9. 6 days (min = 8, max = 9). The male begins to participate more directly in the care of offspring from the fourth day of life of nestlings. The rate of apparent success represents 42. 2% of nests, predation and abandonment 42. 5% and 15. 3%, respectively. Mayfield Estimate success and hypothesis testing using generalized linear models (Program MARK) resulted in 21. 42% and 23. 57%, respectively, and the daily survival rate (DSR) was 0. 939. We tested six hypotheses, two from temporal issues and four related to aspects of nest building. The DSR decreases as the breeding season progresses and also when the nest is becoming older. The plant most used to support nest also had a negative influence on DSR, as well as nests built higher and farther from the edge of the environment. More concealment nests (hidden in the vegetation) showed a decrease in predation risk, increasing the DSR.