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Both frugivores and nectarivores are potentially exposed to dietary ethanol produced by fermentative yeasts which metabolize sugars. Some nectarivorous mammals exhibit a preference for low-concentration ethanol solutions compared to controls of comparable caloric content, but behavioural responses to ethanol by nectar-feeding birds are unknown. We investigated dietary preference by Anna's Hummingbirds (Calypte anna) for ethanol-enhanced sucrose solutions. Via repeated binary-choice experiments, three adult male hummingbirds were exposed to sucrose solutions containing 0%, 1% or 2% ethanol; rates of volitional nectar consumption were measured over a 3 h interval. Hummingbirds did not discriminate between 0% and 1% ethanol solutions, but exhibited significantly reduced rates of consumption of a 2% ethanol solution. Opportunistic measurements of ethanol concentrations within hummingbird feeders registered values peaking at about 0.05%. Ethanol at low concentrations (i.e. up to 1%) is not aversive to Anna's Hummingbirds and may be characteristic of both natural and anthropogenic nectars upon which they feed. Given high daily amounts of nectar consumption by hummingbirds, chronic physiological exposure to ethanol can thus be substantial, although naturally occurring concentrations within floral nectar are unknown. 

Learned traits are thought to be subject to different evolutionary dynamics than other phenotypes, but their evolutionary tempo and mode has received little attention. Learned bird song has been thought to be subject to rapid and constant evolution. However, we know little about the evolutionary modes of learned song divergence over long timescales. Here, we provide evidence that aspects of the territorial songs of Eastern Afromontane sky island sunbirds Cinnyris evolve in a punctuated fashion, with periods of stasis of the order of hundreds of thousands of years or more, broken up by evolutionary pulses. Stasis in learned songs is inconsistent with learned traits being subject to constant or frequent change, as would be expected if selection does not constrain song phenotypes over evolutionary timescales. Learned song may instead follow a process resembling peak shifts on adaptive landscapes. While much research has focused on the potential for rapid evolution in bird song, our results suggest that selection can tightly constrain the evolution of learned songs over long timescales. More broadly, these results demonstrate that some aspects of highly variable, plastic traits can exhibit punctuated evolution, with stasis over long time periods. 

Field biology is an area of research that involves working directly with living organisms in situ through a practice known as “fieldwork.” Conducting fieldwork often requires complex logistical planning within multiregional or multinational teams, interacting with local communities at field sites, and collaborative research led by one or a few of the core team members. However, existing power imbalances stemming from geopolitical history, discrimination, and professional position, among other factors, perpetuate inequities when conducting these research endeavors. After reflecting on our own research programs, we propose four general principles to guide equitable, inclusive, ethical, and safe practices in field biology: be collaborative, be respectful, be legal, and be safe. Although many biologists already structure their field programs around these principles or similar values, executing equitable research practices can prove challenging and requires careful consideration, especially by those in positions with relatively greater privilege. Based on experiences and input from a diverse group of global collaborators, we provide suggestions for action-oriented approaches to make field biology more equitable, with particular attention to how those with greater privilege can contribute. While we acknowledge that not all suggestions will be applicable to every institution or program, we hope that they will generate discussions and provide a baseline for training in proactive, equitable fieldwork practices. 

Abstract The behavioural ecology of host species is likely to affect their microbial communities, because host sex, diet, physiology, and movement behaviour could all potentially influence their microbiota. We studied a wild population of barn owls (Tyto alba) and collected data on their microbiota, movement, diet, size, coloration, and reproduction. The composition of bacterial species differed by the sex of the host and female owls had more diverse bacterial communities than their male counterparts. The abundance of two families of bacteria, Actinomycetaceae and Lactobacillaceae, also varied between the sexes, potentially as a result of sex differences in hormones and immunological function, as has previously been found with Lactobacillaceae in the microbiota of mice. Male and female owls did not differ in the prey they brought to the nest, which suggests that dietary differences are unlikely to underlie the differences in their microbiota. The movement behaviour of the owls was associated with the host microbiota in both males and females because owls that moved further from their nest each day had more diverse bacterial communities than owls that stayed closer to their nests. This novel result suggests that the movement ecology of hosts can impact their microbiota, potentially on the basis of their differential encounters with new bacterial species as the hosts move and forage across the landscape. Overall, we found that many aspects of the microbial community are correlated with the behavioural ecology of the host and that data on the microbiota can aid in generating new hypotheses about host behaviour.