Population size, sex ratio and habitat use of a Red-billed Curassow (Crax blumenbachii Spix, 1825) population reintroduced in Ipaba, MG, Brazil

Author(s)

Joana Carvalhaes Borba de Araujo

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2015-09-25

Examining board members

Adriano Garcia Chiarello; Wesley Rodrigues Silva; Luis Fábio Silveira

• Advisor: Adriano Garcia Chiarello

Abstract

Fragmentation and habitat loss are the two main causes of population and biodiversity decline, followed by overhunting. Such impacts made the Cracidae family the most endangered bird family in American continents. In Brazil, many reintroduction programs focused on cracids. The first one reintroduced the Red-billed Curassow (Crax blumenbachii Spix, 1825) in Ipaba, MG, Brazil. This work aimed to estimate the population size and density, the sex ratio and the landscape use of the Red-billed Curassow population reintroduced in Ipaba. We collected the data along 6 months through line-transects, totalizing 280 km of effort. The analysis followed distance sampling and occupancy protocols. We estimated the population size in 34 (10 111) birds and the density was 2.36 (1.58 7.79) birds/ha. However, we estimated the proportion of area effective used in 21%, what means that the density for such area might be higher. Apparently, the intensity of habitat use is mostly correlated to the understory density and to food supplementation. We estimated the population growth rate in -0.047 (-0.137 0.018), what indicates a decrease. Its possible that the population is declining due to its size, once small populations are more likely to suffer because of demographic, environmental and genetic stochasticity and Allee effect. The same factors might explain the skewed sex ratio, estimated in 0.35 (0.20 0.47). (AU)

• FAPESP's process: 13/08009-7 - Population size, sex ratio and landscape occupancy of a population of red-billed curassow (Crax blumenbachii Spix, 1825) reintroduced in the RPPN Fazenda Macedônia, Ipaba, MG
• Grantee: Joana Carvalhaes Borba de Araujo
• Support Opportunities: Scholarships in Brazil - Master