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Urban birds' detectability is affected by inter‐ and intraspecific variation in shyness
Detection probabilities differ between bird species as a function of their life history and ecological and behavioural traits, inevitably introducing bias in their abundance and occupancy estimates. However, the effects of behavioural traits such as species shyness and vigilance on detectability remain poorly understood. Here, we estimated the species‐specific level of shyness (estimated using flight initiation distance) and vigilance (alert distance) towards the human observer and their within‐species variation for 18 bird species, and accompanied those with species detectability levels estimated during point counts in urban green areas in Prague, Czechia. We found that species detectability increased with inter‐ and intraspecific variation in birds' shyness, but was not associated with the inter‐ and intraspecific variation in birds' vigilance. Our study suggests that considering variation in birds' shyness towards human observers might increase the precision of species abundance and occupancy estimates during field surveys such as point and transect counts, at least in urban habitats.
Sex matters: European urban birds flee approaching women sooner than approaching men
Abstract Flight initiation distance (FID) is a metric often used to study an individual's perceptions of risk when facing a predatory threat. Longer FID indicates lower risk‐taking, while shorter FID identifies bolder individuals who tolerate greater risk. Until now, no studies have tested the potential effect of the observer's sex on the escape behaviour of wild birds. Given observed differences in how laboratory animals may respond to the sex of humans interacting with them, the lack of reports in the field is surprising. In five European countries, we tested whether urban birds perceived the risk posed by approaching female versus male observers differently, using FID as a response variable. First, we matched the female and male observers according to their height and clothing. Then, we fitted Bayesian regression models, controlling for the phylogenetic relatedness of bird species, to test for the effect of human observer sex after controlling for a variety of other important factors known to explain variation in FID (starting distance, flock size, sex of the target bird, land use characteristics and vegetation cover). We found that male birds were more risk‐tolerant than females and – unexpectedly—birds in general escaped sooner when approached by women than by men. The escape difference associated with the observer's sex (~1 m longer when approached by women than by men) was consistent in populations across all five examined European countries. We discussed various hypotheses to explain birds' escape responses related to the observer's sex; however, further research is necessary to fully understand this phenomenon. Read the free Plain Language Summary for this article on the Journal blog.
Environmental and social correlates of the plumage color polymorphism in an urban dweller, feral pigeon (Columba livia f. domestica)
AbstractWe examined how urban environments affect the abundance, proportion, and diversity of plumage color morphs in feral pigeons. Five major plumage color morphs (black, blue, white, red, and mixed) were counted in sixty 25-ha plots in Poznań City (Poland). Generalized additive models were used to study the correlations among abundance, proportion of morphs, and environmental factors. Anthropogenic food sources were positively correlated with the abundance of black morphs and the proportions of black and red morphs. The blue morph abundance peaked at a moderate percentage of tall building cover, but its proportion decreased. A similar decrease was observed in the mixed plumage morphs. The abundance of blue morphs decreased, whereas the abundance of white morphs and the proportion of red morphs increased as the distance from the city center increased. The plumage color morph diversity (Simpson) index was positively correlated with food sources and hedgerow density but negatively correlated with street density. Color morph diversity in the study area may be sustained by differential responses of morphs to the environmental features of the urban environment. However, the positive correlation between the abundance of morphs indicates social attraction rather than social isolation among plumage color morphs.
Urban landscape organization is associated with differences in avian-mediated regulating ecosystem services
Will Brazilian City Dwellers Actively Engage in Urban Conservation? A Case Study with the Charismatic Neotropical Blue-and-Yellow Macaw (Ara ararauna)
The Blue-and-yellow macaw (Ara ararauna) is a charismatic and easily recognized species. While they are classified as being of “least concern” in the International Union for Conservation of Nature (IUCN) Red List, their populations are declining. In Brazil, the accelerated destruction of one of its key habitats, the Cerrado biome, is a principal cause of their decreasing abundance. As with other species affected by loss of the Cerrado, active conservation measures are required. While usually rare in urban ecosystems, Ara ararauna occurs and breeds in small numbers in the city of Rondonópolis, a medium-sized city located in Mato Grosso, Central-West Region of Brazil. Blue-and-yellow macaw pairs nest in the tops of dead palm trees, but as the macaws are nest-site limited and suitable dead trees are scarce in urban areas, the installation of artificial nest sites in domestic backyards could help that urban population to thrive. To investigate whether local people would be willing to engage with conservation efforts and in particular to support macaw conservation, we surveyed the attitudes of Rondonópolis residents to measure: (1) citizens’ preferences among the bird species that occur in the city; (2) the average area of their yards, and (3) the willingness of residents to: (a) plant fruit trees to attract macaws to their yards and (b) to install artificial nests in their yards. Larger and more colorful birds (Ara ararauna, the Red-and-green macaw Ara chloropterus and Toco Toucan Ramphastos toco) were the bird species most valued across all socio-economic groups, suggesting that the charismatic species would be more likely to be supported by urbanites. Overall, people had good biodiversity knowledge, with respondents being able to identify half of our sample of local bird species, on average, and almost half had seen a nest site. The great majority were willing to plant fruit trees (78%) and provide nest sites (70%) for macaws. This willingness to engage was not affected by socioeconomic differences. These data indicate that a municipal macaw conservation program could be successful in Rondonópolis, and we argue that macaws could be a flagship species which would benefit wider efforts to engage Brazilian urbanites in active engagement with nature.