The Size of Winter-Flooded Paddy Fields No Longer Limits the Foraging Habitat Use of the Endangered Crested Ibis (Nipponia nippon) in Winter.

Paddy fields have traditionally been viewed as the key foraging habitats for the endangered crested ibis (Nipponia nippon). With the population of this species now increasing, its distribution has expanded to both lowland areas and outside the nature reserve. However, little is known about the current foraging habitat preferences of these birds, especially during winter. In this research, a total of 54 used sites and 50 unused sites were investigated during winter from December 2011 to January 2012. The results of logistic regression analysis indicate that soil softness, human disturbance, and distance to the nearest road were important factors. For the site plots of winter-flooded paddy fields, the birds prefer the paddy fields with higher coverage of vegetation, except softer foraging sites and lower human-related disturbance. In lowland areas, the size of winter-flooded paddy fields was not a limiting factor, due to the availability of other wetlands capable of providing abundant food. The micro-habitat characteristics were important indicators of foraging habitat quality rather than the size of winter-flooded paddy fields, and the food accessibility may play an important role in the process of foraging habitat use. We suggest the improvement of the foraging micro-habitat and environmental characteristics would be effective in ensuring the availability of food in the dispersed lowland areas. The local people still needed to be encouraged and compensated by their single-cropping cultivation, ploughed the paddy fields after harvesting and irrigated them with shallow water flooded in the original core areas of the nature reserve.

Improved molecular assay for sex identification of the endangered crested Ibis (Nipponia nippon) based on the CHD1 gene and a sex-linked microsatellite locus.

Sex Identification of monomorphic birds, especially endangered avian species, is essential for ecological study and biodiversity conservation. In this study, two popular primer sets of 2550F/2718R and P2/P8, which were designed to amplify different fragments of chromodomain-helicase-DNA binding protein 1 (CHD1) genes mapped on both Z and W chromosomes in birds, were used to identify for the first time the sex of individuals of the endangered species crested ibis (Nipponia nippon) in a large number of samples. An improved primer set of 2467F/2530R was re-designed to be specific to crested ibis following their conserved sequences derived from the 2550F/2718R primers. PCR products of the new primers were conveniently visualized with two bands of 552 base pairs (bp) and 358 bp for females, but a single band of 552 bp for males in routine 1.8% agarose gel. Similarly, the P2/P8 primer set amplified two fragments of 398 bp and 381 bp from females but one fragment of 398 bp from males; however, a high resolution involving 10% Polyacrylamide gel had to be employed to resolve the 17 bp insertions/deletions (in/dels) present between the two amplicons in females. In addition, a microsatellite locus NnNF05 was validated to be sex-linked and shown to be effective in the sexing of crested ibis, supporting its utility in non-invasive sampling. This study provides a rapid, convenient, and reliable molecular assay for improving sex identification in the monomorphic and monogamous crested ibis, and thus facilitates the selection of breeding pairs in captive programs and reintroduction initiatives.