Birds, Volume 5, Issue 2 (June 2024) – 6 articles

More than 40 hypotheses predict associations between features of nest architecture and at least one measure of reproductive success. However, quantitative studies of reproductive consequences of nest characteristics remain scarce. In addition, most studies were conducted on model species of which nests can be easily monitored with artificial nest-boxes. Here, we review the replicability of research protocols and findings in model species, with many repeat studies focusing mainly on nest-size components, animal-derived nest material, or fresh greenery in model species of secondary hole-nesting birds: Blue Tits (Cyanistes caeruleus), Great Tits (Parus major), Tree Swallows (Tachycineta bicolor), and Starlings (Sturnus spp.). The studies looked for correlations between nest traits and aspects of breeding performance that can be easily quantified in the field, such as clutch size, brood size at hatching or fledging, the percentage of eggs that hatch or fledge, or nestling characteristics assumed to reflect qualities associated with survival probabilities (e.g., morphometry, body condition, blood profiles). We discuss the consequences of poor replicability of research methodologies and provide explanations for why many of these studies reported poor associations between nest design and breeding success at different spatiotemporal scales. We also make suggestions for future research. Full article

Bird identification is a necessary skill for citizen science projects, and teaching and learning about species is essential to halt the decline in biodiversity. Here, we investigated bird species knowledge in a case study of Michigan high school students using an online survey. Participants were asked to identify 21 common species, covering a wide range of orders and families. On average, high school students achieved a correct identification score of 35%. The most well-known species were the American Robin, Blue Jay, Cardinal and Turkey Vulture. We found no difference between boys and girls, but identification scores declined with increasing age. Interest was an important predictor of identification knowledge, as were activities (field trips, outings) both in and out of class. Among species traits, high knowledge of a species was positively related to the number of eBird entries (as a proxy for year-round population size), body mass (heavier species were better known) and internet presence. We suggest expanding this study to other states, and we encourage educators and teachers to improve bird knowledge through birding field trips. Full article

Background: The flight initiation distance (FID) measures the distance a bird flees from an approaching predator. Factors such as the frequency of predator approaches, the direction of predator gaze, variations in predator presence across different areas, and the specific behaviors displayed by predators can all affect the FID. For birds, people can assume the role of predators. Methods: This study aimed to evaluate whether the FID of the species Sicalis flaveola (Saffron finch, Aves, Passeriformes) is influenced by the number of people and their gaze direction, comparing areas with the greater and lesser flow of people and relating to the types of behavior exhibited by the birds. Results: The results showed that the number of people walking towards the bird influenced the escape behavior, with more people generating longer FIDs than fewer people. If the approach was with the eyes fixed on the birds, the FIDs were longer. When birds were alert, FIDs were longer. Conclusion: Overall, the findings imply that birds exhibit nuanced reactions to human presence, even in areas with frequent human encounters, highlighting their advanced capacity for assessing and responding to perceived risks. Full article

The diet and feeding behavior of South Polar Skuas (Stercorarius maccormicki) are well studied within the species’ breeding range but are poorly understood on the Haswell Islands. The aim of this study was to determine how South Polar Skuas use available resources during the pre-breeding and breeding periods at the Haswell Archipelago (66°31′ S, 93°01′ E, Davis Sea, Southern Ocean) under conditions of prolonged human activity. I studied pellets, spontaneous regurgitation, and stomach contents of feathered birds to study the diet of skuas and used direct observations of their feeding behavior. South Polar Skuas at the Haswell Islands fed primarily on the Emperor Penguin (Aptenodytes forsteri) colony and on terrestrial resources in the Adélie Penguin (Pygoscelis adeliae) and fulmarine petrel colonies. The dominant prey of skuas were breeding Antarctic penguins. Emperor Penguins and Adélie Penguins make up the bulk of the skuas’ diet in the pre-breeding and breeding periods. Surface feeding at sea was observed in the post-breeding period. In recent decades, kitchen waste supported the skua population. Scavenging (placenta and feces of Weddell seals [Leptonychotes weddellii], frozen eggs, chicks and adults of breeding bird species, kitchen refuse) is the dominant strategy for obtaining food. Adélie Penguin eggs and chicks were the main food items of the South Polar Skuas in the Haswell Archipelago. Skua predation could potentially influence the breeding success of Adélie Penguins and fulmarine petrels, but the extent of the impact is unknown. The impact of the South Polar Skua on Emperor Penguins is negligible because skuas feed mainly on frozen chicks and eggs of the species. Full article

Heron colonies are dynamic components of wetlands. Therefore, their systematic monitoring is important for the management of both birds and wetlands. During the period 1988–2018, we counted breeding pairs of seven colonial breeding heron species at 65 colonies across 37 wetlands in Greece. We considered as annual variables of a population: (a) years since 1988, (b) Natura 2000 network inclusion, (c) protected area management authority overseeing, (d) wetland type (new or restored), and (e) new colonies (established after 2003). The Cattle Egret Bubulcus ibis and the Squacco Heron Ardeola ralloides had a positive breeding population trend. The Black-crowned Night Heron Nycticorax nycticorax, Little Egret Egretta garzetta, and Grey Heron Ardea cinerea had a negative trend, while the Purple Heron Ardea purpurea population was stable. The Great White Egret Ardea alba bred sporadically at only a few sites which precluded the evaluation of its population trend. The informative population variables differed among species, even of those at the same colony, which suggests trends are also affected by conditions at wintering grounds. The study highlights the need for the systematic monitoring of heron colonies and the protection of foraging/breeding areas in order to reverse the observed negative population trends. Full article

Understanding how humans perceive animals is important for biodiversity conservation, however, only a few studies about this issue have been carried out in South America. We selected two Brazilian cities to assess people’s perceptions of birds: Bauru (São Paulo, Brazil) and Belo Horizonte (Minas Gerais, Brazil). From the available bird data for each city, we developed a questionnaire and applied it between September 2020 and June 2021. The data obtained were analyzed by simple counts, a Likert scale, and percentages. Also, human feelings related to birds were placed on the Free Word Cloud Generator website. Our study confirmed that most respondents were aware of the importance of birds to ecological balance and that respondents had a generally positive attitude towards most of the bird species. However, they disliked exotic species such as the Domestic Dove and the House Sparrow, which are associated with disease, dirt, and disgust. Respondents also underestimated the number of birds that can live in urban areas and the song of birds is still a sense less experienced and perceived by people. Understanding these human–biodiversity relationships can help guide public policies and environmental education activities. Full article