On the feeding biomechanics of nectarivorous birds.

Nectar-feeding birds employ unique mechanisms to collect minute liquid rewards hidden within floral structures. In recent years, techniques developed to study drinking mechanisms in hummingbirds have prepared the groundwork for investigating nectar feeding across birds. In most avian nectarivores, fluid intake mechanisms are understudied or simply unknown beyond hypotheses based on their morphological traits, such as their tongues, which are semi-tubular in sunbirds, frayed-tipped in honeyeaters and brush-tipped in lorikeets. Here, we use hummingbirds as a case study to identify and describe the proposed drinking mechanisms to examine the role of those peculiar traits, which will help to disentangle nectar-drinking hypotheses for other groups. We divide nectar drinking into three stages: (1) liquid collection, (2) offloading of aliquots into the mouth and (3) intraoral transport to where the fluid can be swallowed. Investigating the entire drinking process is crucial to fully understand how avian nectarivores feed; nectar-feeding not only involves the collection of nectar with the tongue, but also includes the mechanisms necessary to transfer and move the liquid through the bill and into the throat. We highlight the potential for modern technologies in comparative anatomy [such as microcomputed tomography (µCT) scanning] and biomechanics (such as tracking BaSO4-stained nectar via high-speed fluoroscopy) to elucidate how disparate clades have solved this biophysical puzzle through parallel, convergent or alternative solutions.

Tracking Small Animals in Complex Landscapes: A Comparison of Localisation Workflows for Automated Radio Telemetry Systems.

Automated radio telemetry systems (ARTS) have the potential to revolutionise our understanding of animal movement by providing a near-continuous record of individual locations in the wild. However, localisation errors in ARTS data can be very high, especially in natural landscapes with complex vegetation structure and topography. This curtails the research questions that may be addressed with this technology. We set up an ARTS grid in a valley with heterogeneous vegetation cover in the Colombian high Andes and applied an analytical pipeline to test the effectiveness of localisation methods. We performed calibration trials to simulate animal movement in high- or low-flight, or walking on the ground, and compared workflows with varying decisions related to signal cleaning, selection, smoothing, and interpretation, along with four multilateration approaches. We also quantified the influence of spatial features on the system's accuracy. Results showed large variation in localisation error, ranging between 0.4-43.4 m and 474-1929 m, depending on the localisation method used. We found that the selection of higher radio signal strengths and data smoothing based on the temporal autocorrelation are useful tools to improve accuracy. Moreover, terrain ruggedness, height of movement, vegetation type, and the location of animals inside or outside the grid area influence localisation error. In the case of our study system, thousands of location points were successfully estimated for two high-altitude hummingbird species that previously lacked movement data. Our case study on hummingbirds suggests ARTS grids can be used to estimate small animals' home ranges, associations with vegetation types, and seasonality in occurrence. We present a comparative localisation pipeline, highlighting the variety of possible decisions while processing radio signal data. Overall, this study provides guidance to improve the resolution of location estimates, broadening the application of this tracking technology in the study of the spatial ecology of wild populations.

Los sistemas de radio telemetría automatizada (ARTS, por sus siglas en inglés) tienen el potencial de revolucionar nuestro entendimiento de los movimientos de animales, ya que pueden generar registros de individuos en la naturaleza a escalas temporales muy finas. Sin embargo, el error de localización asociado a los datos generados por un sistema ARTS puede ser muy alto, especialmente en paisajes naturales con complejidad en su estructura vegetal y su topografía. Esto necesariamente limita las preguntas de investigación que se pueden abordar con dicha tecnología. En este estudio, instalamos una grilla ARTS en un valle con una cobertura vegetal heterogénea en ecosistemas altoandinos de Colombia, y evaluamos la efectividad de métodos de localización. Hicimos ensayos de calibración para simular el movimiento de animales tanto en vuelo alto y bajo como caminando sobre el piso, y comparamos procesos de localización con diferentes decisiones en los pasos de limpieza, selección, atenuación e interpretación de las señales de radio registradas. Además, probamos cuatro métodos de multilateración diferentes. También cuantificamos el efecto de características espaciales sobre la exactitud de la grilla ARTS. Los resultados muestran una gran variación en el error de localización, con coordenadas estimadas a sólo 0.4­43.4 m de la ubicación real hasta 474­1929 m, dependiendo del método de localización empleado. Encontramos que la selección de señales de radio más altas y la atenuación de los datos con base en la autocorrelación temporal de los datos de movimiento, son herramientas útiles para mejorar la exactitud del sistema. Además, la rugosidad del terreno, la altura del movimiento, el tipo de vegetación y la ubicación de los animales dentro o fuera de la grilla son variables que afectan el error de localización. Para nuestro caso de estudio, miles de puntos de ubicación fueron estimados para dos especies de colibríes que previamente no tenían datos de movimiento. Nuestro caso de estudio sobre colibríes de alta montaña sugiere que grillas ARTS son útiles para inferir rangos de hogar, asociaciones con tipos de vegetación y ocurrencia estacional de especies de animales pequeños. Presentamos una metodología comparativa de localización, resaltando la variedad de posibles decisiones durante el procesamiento de datos de señales de radio. Este estudio provee una guía para mejorar la resolución de estimados de ubicación, y amplía la aplicación de esta tecnología para el estudio de la ecología espacial de poblaciones silvestres.

Variable evidence for convergence in morphology and function across avian nectarivores.

Nectar-feeding birds provide an excellent system in which to examine form-function relationships over evolutionary time. There are many independent origins of nectarivory in birds, and nectar feeding is a lifestyle with many inherent biophysical constraints. We review the morphology and function of the feeding apparatus, the locomotor apparatus, and the digestive and renal systems across avian nectarivores with the goals of synthesizing available information and identifying the extent to which different aspects of anatomy have morphologically and functionally converged. In doing so, we have systematically tabulated the occurrence of putative adaptations to nectarivory across birds and created what is, to our knowledge, the first comprehensive summary of adaptations to nectarivory across body systems and taxa. We also provide the first phylogenetically informed estimate of the number of times nectarivory has evolved within Aves. Based on this synthesis of existing knowledge, we identify current knowledge gaps and provide suggestions for future research questions and methods of data collection that will increase our understanding of the distribution of adaptations across bodily systems and taxa, and the relationship between those adaptations and ecological and evolutionary factors. We hope that this synthesis will serve as a landmark for the current state of the field, prompting investigators to begin collecting new data and addressing questions that have heretofore been impossible to answer about the ecology, evolution, and functional morphology of avian nectarivory.

Raspberry Pi nest cameras: An affordable tool for remote behavioral and conservation monitoring of bird nests.

Bespoke (custom-built) Raspberry Pi cameras are increasingly popular research tools in the fields of behavioral ecology and conservation, because of their comparative flexibility in programmable settings, ability to be paired with other sensors, and because they are typically cheaper than commercially built models.Here, we describe a novel, Raspberry Pi-based camera system that is fully portable and yet weatherproof-especially to humidity and salt spray. The camera was paired with a passive infrared sensor, to create a movement-triggered camera capable of recording videos over a 24-hr period. We describe an example deployment involving "retro-fitting" these cameras into artificial nest boxes on Praia Islet, Azores archipelago, Portugal, to monitor the behaviors and interspecific interactions of two sympatric species of storm-petrel (Monteiro's storm-petrel Hydrobates monteiroi and Madeiran storm-petrel Hydrobates castro) during their respective breeding seasons.Of the 138 deployments, 70% of all deployments were deemed to be "Successful" (Successful was defined as continuous footage being recorded for more than one hour without an interruption), which equated to 87% of the individual 30-s videos. The bespoke cameras proved to be easily portable between 54 different nests and reasonably weatherproof (~14% of deployments classed as "Partial" or "Failure" deployments were specifically due to the weather/humidity), and we make further trouble-shooting suggestions to mitigate additional weather-related failures.Here, we have shown that this system is fully portable and capable of coping with salt spray and humidity, and consequently, the camera-build methods and scripts could be applied easily to many different species that also utilize cavities, burrows, and artificial nests, and can potentially be adapted for other wildlife monitoring situations to provide novel insights into species-specific daily cycles of behaviors and interspecies interactions.