Relationship among vegetation structure and mixed-species flocks composition along the latitudinal gradient of the subtropical montane forest of the Yungas, Argentina.

The structural and physiognomic characteristics of forests and mountain forest are fundamental aspects that influence the richness, abundance and composition in the bird community. The objective of the present work was to analyse how the vegetation structure could influence the species composition of mixed-species flocks (MSF), along the latitudinal gradient of the subtropical montane forest of the Yungas of Argentina. Eight sites were studied along the 700 km of distribution of the Argentine Yungas. Richness and abundance of MSF were determined. In addition, different variables of composition and structure of the vegetation were analysed. Multivariate analysis indicated that vertical strata coverage and litter depth were the main variables associated with changes in the species composition of MSF along the gradient. Variation in MSF composition within the Yungas was associated with the physiognomy of the subtropical montane forest, which could indicate that it is strongly linked to the condition of the local vegetation. Substantial changes in vegetation could drastically change the composition of the resident flocks. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.

Are birds more afraid in urban parks or cemeteries? A Latin American study contrasts with results from Europe.

The escape behaviour, measured as flight initiation distance (FID; the distance at which individuals take flight when approached by a potential predator, usually a human in the study systems), is a measure widely used to study fearfulness and risk-taking in animals. Previous studies have shown significant differences in the escape behaviour of birds inhabiting cemeteries and urban parks in European cities, where birds seem to be shyer in the latter. We collected a regional dataset of the FID of birds inhabiting cemeteries and parks across Latin America in peri-urban, suburban and urban parks and cemeteries. FIDs were recorded for eighty-one bird species. Mean species-specific FIDs ranged from 1.9 to 19.7 m for species with at least two observations (fifty-seven species). Using Bayesian regression modelling and controlling for the phylogenetic relatedness of the FID among bird species and city and country, we found that, in contrast to a recent publication from Europe, birds escape earlier in cemeteries than parks in the studied Latin American cities. FIDs were also significantly shorter in urban areas than in peri-urban areas and in areas with higher human density. Our results indicate that some idiosyncratic patterns in animal fearfulness towards humans may emerge among different geographic regions, highlighting difficulties with scaling up and application of regional findings to other ecosystems and world regions. Such differences could be associated with intrinsic differences between the pool of bird species from temperate European and mostly tropical Latin American cities, characterized by different evolutionary histories, but also with differences in the historical process of urbanization.