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Gut microbiota plays an important role in animals and are considered microbial organs. Hornbill and toucan are birds of the same ecotypes with high appreciative value. In this study, we characterized and compared the gut microbiota of toco toucan (Ramphastos toco), great hornbill (Buceros bicornis) and wreathed hornbill (Rhyticeros undulatus) using 16S rRNA high-throughput sequencing technology, and further discussed the influence of host bird genetics on its gut microbiota. We identified 10,847 operational taxonomic units (OTUs) from the hyper-variable V4-V5 region, representing 14 phyla that were dominated by the Firmicutes, Proteobacteria, Cyanobacteria, Fusobacteria, Actinobacteria, and Bacteroidetes. Alpha diversity indices showed no significant difference among the three species (p > 0.1). However, great hornbill and toco toucan shared a high number of OTUs. Principal component analysis also revealed highly similar gut microbiotas between the two distant species. Therefore, environmental factors might dominate over host genetics in shaping the gut microbiotas of hornbill and toucan. Our study would contribute in elucidating adaptation of the hornbill and toucan to environmental change., (© 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

Two major bile acids were isolated from the gallbladder bile of two hornbill species from the Bucerotidae family of the avian order Bucerotiformes Buceros bicornis (great hornbill) and Penelopides panini (Visayan tarictic hornbill). Their structures were determined to be 3α,7α,24-dihydroxy-5β-cholestan-27-oic acid and its 12α-hydroxy derivative, 3α,7α,12α,24-tetrahydroxy-5β-cholestan-27-oic acid (varanic acid, VA), both present in bile as their corresponding taurine amidates. The four diastereomers of varanic acid were synthesized and their assigned structures were confirmed by X-ray crystallographic analysis. VA and its 12-deoxy derivative were found to have a (24R,25S)-configuration. 13 additional hornbill species were also analyzed by HPLC and showed similar bile acid patterns to B. bicornis and P. panini. The previous stereochemical assignment for (24R,25S)-VA isolated from the bile of varanid lizards and the Gila monster should now be revised to the (24S,25S)-configuration.

Great hornbills (Buceros bicornis) are a long-lived, monogamous species that forms strong pair-bonds, and mate compatibility is thought to be important for successful reproduction. Within AZA, great hornbills are listed as a red SSP. The population consists of a limited number of individuals that do not breed reliably, and improving reproduction is a top priority for the Coraciiformes TAG. To better understand mating behavior and evaluate mate compatibility, this study documented the behavior of pairs of great hornbills during and immediately after courtship. Using live observations, the study followed one female, an experienced and successful breeder, as she was paired with four successive males over 11 breeding seasons. Initially, males frequently vocalized, investigated the nest, and approached the female. As the female spent more time in the nest, these behaviors were replaced by regurgitation and food offering. The female was most often observed plastering and vocalizing. Behavioral differences between successful and unsuccessful pairs, possibly indicative of pair compatibility, included rates of approaching, billing, and biting. Numerous behaviors occurred more frequently during years that a chick hatched, including pseudoregurgitation, regurgitation, offering food items, and nest investigation. Males also spent more time in proximity to both the female and the nest during years that a chick hatched. Together, these results suggest that the amount of time pairs spend in proximity, the amount of time a male spends near the nest, and the frequency of certain behaviors may help evaluate compatibility and the likelihood of successful reproduction for pairs of great hornbills., (© 2015 Wiley Periodicals, Inc.)