In mutualistic interactions, all parties are usually considered to benefit; yet there may be asymmetries in mutualisms where some partners/individuals benefit more than others. Such is thought to be the case in mixed-species flocks of birds, where following species are thought to benefit more than leading species, and leading species may not be able to escape the association if they are subordinate to other species. We measured dominance and affiliation patterns of a mixed-species flock system of southern China in an aviary where these variables could be measured in a standardized way. In eight wild-caught flocks, the leading species, David's Fulvetta (Alcippe davidi), was usually among the more subordinate flock members (ranking 9 of 13 species, with the the most dominant species ranked number one, and dominance measured by normalized David's scores). Dominance was strongly influenced by body mass, and not by bill length or the number of individuals. Female fulvettas in particular tended to be among the most subordinate individuals in the flock. There was evidence of a negative relationship between a species pair's affiliation, measured as the percentage of all observations in which these two species were found perching together, and their difference in ranking in the dominance hierarchy, particularly when some ground species, which are not likely to remain in flocks long term, were removed from the analysis. Species pairs that had more pronounced differences in their dominance rankings were less likely to be affiliated, which is consistent with the idea that subordinate species may avoid dominants. David's Fulvetta is a strong information provider, so other species are likely benefitted in this relationship. Our data suggest one reason that fulvettas stay in flocks is that they may be subordinate and therefore have little control over who associates with them.

Birds maintain complex and intimate associations with a diverse community of microbes in their intestine. Multiple invasive and non-invasive sampling methods are used to characterize these communities to answer a multitude of eco-evolutionary questions related to host-gut microbiome symbioses. However, the comparability of these invasive and non-invasive sampling methods is sparse with contradicting findings. Through performing a network meta-analysis for 13 published bird gut microbiome studies, here we attempt to investigate the comparability of these invasive and non-invasive sampling methods. The two most used non-invasive sampling methods (cloacal swabs and fecal samples) showed significantly different results in alpha diversity and taxonomic relative abundances compared to invasive samples. Overall, non-invasive samples showed decreased alpha diversity compared to intestinal samples, but the alpha diversities of fecal samples were more comparable to the intestinal samples. On the contrary, the cloacal swabs characterized significantly lower alpha diversities than in intestinal samples, but the taxonomic relative abundances acquired from cloacal swabs were similar to the intestinal samples. Phylogenetic status, diet, and domestication degree of host birds also influenced the differences in microbiota characterization between invasive and non-invasive samples. Our results indicate a general pattern in microbiota differences among intestinal mucosal and non-invasive samples across multiple bird taxa, while highlighting the importance of evaluating the appropriateness of the microbiome sampling methods used to answer specific research questions. The overall results also suggest the potential importance of using both fecal and cloacal swab sampling together to properly characterize bird microbiomes.

Bird photography is a popular and growing form of ecotourism that contributes to the economic growth of local communities, but its disturbance to bird reproduction remains understudied. We worked in a tropical forest of southern China, which has experienced a sharp increase in the number of photographers in recent years. We compared nests that were photographed and those that were not, in their nest predation and parental feeding rates. Including nests of 42 species, the results demonstrate that the predation rate of nests that were not photographed (incubation stage: 43.3% of 194 nests; nestling stage: 34.5% of 110 nests) was significantly higher than that of photographed ones (incubation: 2.4% of 83 nests; nestling: 11.1% of 81 nests). Among different nest types, open cup nests in shrub and trees were most affected by photography, in both incubation and nestling stages. Of five factors investigated, including three natural factors (nest stage, structure and position), and two anthropogenic factors (photography and distance to forest edge), only photographic disturbance and nest structure had significant effects (open nests had higher predation). The feeding frequency at nests when photographers were present was not strongly different from when they were not present. Human activity therefore had no negative effects on the birds, but showed a positive effect on their nesting success, in terms of reducing nest predation rates. However, there needs to be further assessment of other aspects of nesting (e.g., clutch size, duration of nestlings in nests), and other kinds of stress responses (e.g., hormonal changes), before the total effect of bird photography can be understood.