Sex identification and sex ratio of the American flamingo Phoenicopterus ruber using molecular techniques: importance for management in zoological collections

Abstract

In recent years, zoos have acquired an important role in biodiversity conservation, especially for birds which are the most representative group in zoos. Proper management and conservation of species within zoos requires knowledge of sex composition within collections, to form successful breeding groups. However, many bird species are monomorphic, making it difficult to differentiate males from females. This study employed a fragment-specific PCR technique using two primers, 2550F and 2718R exclusively for the CHD-W and CHD-Z introns of the CHD gene, to identify males and females in two collections of American flamingo Phoenicopterus ruber in Mexican zoos. In one zoo, all the adults acquired by the zoo were sampled (n=14); in the other, adults acquired by the zoo (n=92) and individuals hatched in the zoo (n=52) were sampled. Sex was identified with 95.6–100% effectiveness. The sex ratio for adult individuals acquired by both collections was about 1:1, while it was 1.89:1 in favour of males for individuals hatched in the zoo. The high quality of maternal conditions may overproduce sons (Trivers-Willard hypothesis) in flamingos hatched in this zoo. Despite its importance for zoo management and conservation programmes, this study is one of the first to use a molecular technique to evaluate sex ratio in captive American flamingo. The male-skewed sex ratio in one of the collections could have a negative impact on the long-term survival of this population. In conclusion, monitoring sex ratio in flamingos is important to improve management practices in zoos.