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Foraging behaviors of animals that promote efficiency can be explained by optimal foraging theory. Previous research suggests that factors associated with nutrition (e.g., oil content) or size (e.g., seed weight and depth) influence the foraging behaviors of Black-capped Chickadees (Poecile atricapillus). In February and March 2020 we examined seed selection in Black-capped Chickadees. Specifically, we collected black oil sunflower seeds discarded from a tube bird feeder by Black-capped Chickadees and compared them with seeds selected at random from the feeder. We measured the depth, length, width, and weight of 180 sunflower seeds. We found that the size and weight of the seeds were both important factors for chickadees in seed selection. In addition, chickadees preferred seeds that were significantly heavier when adjusted for seed size. These findings suggest that Black-capped Chickadees select seeds based on their size and weight to maximize the nutritional content they intake. Chickadees therefore must also be able to distinguish small differences in seed weight, which may maximize their acquired energy while decreasing the risks of predation when individuals are exposed during foraging. Los comportamientos de forrajeo de animales que promueven la eficiencia pueden ser explicados por la teoría del forrajeo óptimo. Investigaciones previas sugieren que factores asociados a la nutrición (ej., contenido de aceites) o tamaño (ej., espesor y peso de las semillas) influyen en los comportamientos de forrajeo del carbonero cabecinegro (Poecile atricapillus). En febrero y marzo del 2020 examinamos la selección de semillas del carbonero cabecinegro. Específicamente, colectamos semillas de girasol de aceite negro descartadas de un comedero de tubo para aves por el carbonero cabecinegro y las comparamos con semillas seleccionadas al azar del comedero. Medimos el espesor, largo, ancho y peso de 180 semillas de girasol. Encontramos que el tamaño y el peso de las semillas eran factores importantes para los carboneros al seleccionar las semillas. Además, los carboneros prefirieron semillas que eran significativamente más pesadas al ajustar las medidas por tamaño de semilla. Estos hallazgos sugieren que los carboneros cabecinegros seleccionan las semillas con base en el tamaño y el peso para maximizar el contenido nutricional que ingieren. Los carboneros deben entonces poder distinguir pequeñas diferencias de peso de las semillas, lo que podría maximizar su energía adquirida y a la vez disminuiría los riesgos de depredación a los que se someten los individuos durante el forrajeo. Palabras clave: aceite negro, comedero de aves, forrajeo óptimo, semilla de girasol.

Today, according to the US Fish and Wildlife Service, more than fifty million Americans feed birds around their homes, and over the last sixty years, billions of pounds of birdseed have filled millions of feeders in backyards everywhere. Feeding Wild Birds in America tells why and how a modest act of provision has become such a pervasive, popular, and often passionate aspect of people’s lives. Each chapter provides details on one or more bird-feeding development or trend including the “discovery” of seeds, the invention of different kinds of feeders, and the creation of new companies. Also woven into the book are the worlds of education, publishing, commerce, professional ornithology, and citizen science, all of which have embraced bird feeding at different times and from different perspectives. The authors take a decade-by-decade approach starting in the late nineteenth century, providing a historical overview in each chapter before covering topical developments (such as hummingbird feeding and birdbaths). On the one hand, they show that the story of bird feeding is one of entrepreneurial invention; on the other hand, they reveal how Americans, through a seemingly simple practice, have come to value the natural world.

Mixed-species groups and aggregations are quite common and may provide substantial fitness-related benefits to group members. Individuals may benefit from the overall size of the mixed-species group or from the diversity of species present, or both. Here we exposed mixed-species flocks of songbirds (Carolina chickadees, Poecile carolinensis, tufted titmice, Baeolophus bicolor, and the satellite species attracted to these two species) to three different novel feeder experiments to assess the influence of mixed-species flock size and composition on ability to solve the feeder tasks. We also assessed the potential role of habitat density and traffic noise on birds' ability to solve these tasks. We found that likelihood of solving a novel feeder task was associated with mixed-species flock size and composition, though the specific social factor involved depended on the particular species and on the novel feeder. We did not find an influence of habitat density or background traffic noise on likelihood of solving novel feeder tasks. Overall, our results reveal the importance of variation in mixed-species group size and diversity on foraging success in these songbirds.

At a time of unprecedented biodiversity loss, researchers are increasingly recognizing the broad range of benefits provided to humankind by nature. However, as people live more urbanized lifestyles there is a progressive disengagement with the natural world that diminishes these benefits and discourages positive environmental behaviour. The provision of food for garden birds is an increasing global phenomenon, and provides a readily accessible way for people to counter this trend. Yet despite its popularity, quite why people feed birds remains poorly understood. We explore three loosely defined motivations behind bird feeding: that it provides psychological benefits, is due to a concern about bird welfare, and/or is due to a more general orientation towards nature. We quantitatively surveyed households from urban towns in southern England to explore attitudes and actions towards garden bird feeding. Each household scored three Likert statements relating to each of the three motivations. We found that people who fed birds regularly felt more relaxed and connected to nature when they watched garden birds, and perceived that bird feeding is beneficial for bird welfare while investing time in minimising associated risks. Finally, feeding birds may be an expression of a wider orientation towards nature. Overall, we found that the feelings of being relaxed and connected to nature were the strongest drivers. As urban expansion continues both to threaten species conservation and to change peoples' relationship with the natural world, feeding birds may provide an important tool for engaging people with nature to the benefit of both people and conservation.

Anthropogenic food provisioning of wildlife can alter the frequency of contacts among hosts and between hosts and environmental sources of pathogens. Despite the popularity of garden bird feeding, few studies have addressed how feeders influence host contact rates and disease dynamics. We experimentally manipulated feeder density in replicate aviaries containing captive, pathogen-naive, groups of house finches (Haemorhous mexicanus) and continuously tracked behaviours at feeders using radio-frequency identification devices. We then inoculated one bird per group with Mycoplasma gallisepticum (Mg), a common bacterial pathogen for which feeders are fomites of transmission, and assessed effects of feeder density on house finch behaviour and pathogen transmission. We found that pathogen transmission was significantly higher in groups with the highest density of bird feeders, despite a significantly lower rate of intraspecific aggressive interactions relative to the low feeder density groups. Conversely, among naive group members that never showed signs of disease, we saw significantly higher concentrations of Mg-specific antibodies in low feeder density groups, suggesting that birds in low feeder density treatments had exposure to subclinical doses of Mg. We discuss ways in which the density of garden bird feeders could play an important role in mediating the intensity of Mg epidemics. This article is part of the theme issue ‘Anthropogenic resource subsidies and host–parasite dynamics in wildlife'.

Mixed-species groups and aggregations are quite common and may provide substantial fitness-related benefits to group members. Individuals may benefit from the overall size of the mixed-species group or from the diversity of species present, or both. Here we exposed mixed-species flocks of songbirds (Carolina chickadees, Poecile carolinensis , tufted titmice, Baeolophus bicolor , and the satellite species attracted to these two species) to three different novel feeder experiments to assess the influence of mixed-species flock size and composition on ability to solve the feeder tasks. We also assessed the potential role of habitat density and traffic noise on birds’ ability to solve these tasks. We found that likelihood of solving a novel feeder task was associated with mixed-species flock size and composition, though the specific social factor involved depended on the particular species and on the novel feeder. We did not find an influence of habitat density or background traffic noise on likelihood of solving novel feeder tasks. Overall, our results reveal the importance of variation in mixed-species group size and diversity on foraging success in these songbirds.

Bird–window collisions at houses have been identified as a significant source of mortality for North American birds, but which types of houses and windows are most problematic remains poorly understood. We assessed how neighborhood type, yard conditions, house attributes, and window type influenced collision rates. Data were collected from citizen scientists across Alberta, Canada, who surveyed their houses daily. In relation to the best-fitting model, the yard model explained 58.1% of the explained deviance, the neighborhood model 45.6%, and the house model 42.6%. The factors that had the largest effect for predicting collision risk included season and whether the house was in a rural or an urban area (rural areas in the fall had a 6.0× higher collision risk than urban areas in the winter), the height of vegetation in the front yard of the house (trees >2 stories high increased collision risk by 3.6× compared to houses with no trees), and the presence of a bird feeder (which increased collision risk by 1.7×). This suggests that multiple factors affect collision rates and that the suitability of a yard as bird habitat is likely a key driver. Given that few homeowners are likely to take an approach that reduces the number of birds in their yards, future focus needs to be given to bird-friendly urban design and developing the most effective window deterrents so that collisions can be reduced and birds enjoyed in urban environments.