Abstract:The Fork-tailed Flycatcher Tyrannus savana (Tyrannidae) is a migratory passerine that occurs in central Brazil between August and February. Its breeding biology is still little known, and this study reports data on breeding season, incubation and nestling periods, nest and egg characteristics, nest success and predation rate. We searched for nests at "Estação Ecológica de Águas Emendadas" (ESECAE) and its surroundings, Distrito Federal, Brazil, in the breeding seasons of 2002 to 2007. We monitored 78 nests each 2-4 days. Breeding season started in late September and lasted until mid December. Incubation lasted 13.6 ± 0.4 days (n = 21) (mean ± SE) and nestling period lasted 15 ± 0.4 days (n = 27). Most nests (n = 39) were found in "cerrado ralo" vegetation and were built on plants of the genus Kielmeyera. Clutch size ranged from 1 to 3 eggs, with an average of 2.5 ± 0.3 eggs. Egg length and width averaged 22.2 ± 0.2 mm and 15.8 ± 0.1 mm (n = 6), respectively, and the average weight was 3.0 ± 0.2 g (n = 5). Thirty (52.5%) nests were successful, 24 (43.9%) were predated and only two (3.7%) were abandoned. Egg success was 39.2 ± 1.4% and mean hatching rate was 0.6 ± 0.2 fledglings/egg. Overall productivity was 1.0 ± 0.3 fledglings per nest, and fecundity rate was 1.4 ± 0.4 fledglings per female. Nest success (Mayfield method) was 45.9% ± 1.1, with no significant difference between the average daily survival rate between egg and nestling periods. Several of the estimated parameters for T. savana revealed to be different than expected for a tropical flycatcher. Resumo: A tesourinha Tyrannus savana é um Passeriforme (Tyrannidae) migratório que ocorre no Planalto central entre os meses de agosto e fevereiro. Sua biologia reprodutiva é ainda pouco conhecida e foi abordada pelo presente estudo quanto aos seguintes aspectos: período reprodutivo, tamanho da ninhada, tempo de incubação e de permanência dos ninhegos no ninho, características dos ninhos e ovos, taxa de sucesso dos ninhos e taxa de predação. O estudo foi realizado na Estação Ecológica Águas Emendadas e em fragmentos do entorno, DF, nas estações reprodutivas de 2002 a 2007. Os ninhos (n = 78) foram monitorados em intervalos de 2-4 dias. O período reprodutivo estendeu-se de setembro a dezembro. O período médio de incubação foi de 13,6 ± 0,4 dias (n = 21) (média ± EP), e a permanência dos ninhegos no ninho foi de 15 ± 0,4 dias (n = 27). A maioria dos ninhos (n = 39) foi encontrada em cerrado ralo e em plantas-suporte do gênero Kielmeyera. O tamanho da ninhada variou de 1 a 3 ovos com média de 2,5 ± 0,3 ovos. O comprimento e a largura média dos ovos foram de 22,2 ± 0,2 mm e 15,8 ± 0,1 mm (n = 6), respectivamente, e o peso médio foi de 3,0 ± 0,2 g (n = 5). Trinta ninhos (52,5%) tiveram sucesso, 24 (43,8%) foram predados e apenas dois (3,7%) foram abandonados. O sucesso dos ovos foi de 39,2 ± 1,4%, sendo a taxa de eclosão de 0,6 ± 0,2 filhotes/ovo, a fecundidade de 1,5 ± 0,4 filhotes/fêmea e da produção anual de filhotes de 1,0 ± 0,3 filhotes/ninho. O sucess...

SummaryReducing the time that birds' eggs are exposed during incubation in the wild is a management strategy with the potential to reduce nest predation rates, enhance breeding success and increase the population size of endangered species. We tested whether manipulation of clutches through artificial incubation of Lesser Elaenia Elaenia chiriquensis eggs and subsequent reintroduction of new-born nestlings to their original nest, and the use of adoptive parents, were efficient ways of increasing the population size of this species. We evaluated the financial cost and benefit of three different management strategies of artificial egg incubation with reintroduction of nestlings to the original nest. We searched for nests and manipulated eggs during the breeding seasons of 2009 and 2010 in a savanna reserve in central Brazil. Real eggs were replaced by artificial eggs and artificially incubated. The following breeding parameters were monitored: hatching rate, fledgling productivity, daily survival rate of nestlings and nest success. The effect of nest monitoring frequency (daily or every 3-4 days) on breeding parameters was also tested. Hatching rate was much higher amongst artificially incubated eggs than naturally incubated eggs. Artificially incubated clutches presented higher rates of fledgling production and apparent nest success than non-manipulated clutches. Clutch manipulation did not interfere with nestling daily survival rate. Daily monitoring did not have negative effects. The clutch manipulation methodology we used proved to be viable and is a potential tool for increasing population size.