Search

The Black Grouse Tetrao tetrix is primarily a lekking species, although in some populations solitary display is also common. We analysed data from a 25-year-long survey of an increasing Black Grouse population in the western Italian Alps in order to test whether the numbers of males adopting different tactics conformed to patterns expected, based on the hypothesis that dominant birds occupy the leks and solitary displaying birds are subordinate, and that the tendency for birds to be excluded from leks increases with lek size. Four predictions were made to test this hypothesis: (1) the proportion of solitary males would increase as the overall population increases, (2) there would be a threshold at which there is little or no increase in the size of the lekking population, but continued increase in the population of solitary displaying birds, (3) available lek habitat would be occupied prior to an increase in solitary displaying males, and (4) there would be an increase in the use of less preferred habitat by solitary displaying males as the total population increases. Population trends varied according to display status, in that the lekking population reached an apparent threshold while the number of solitary males continued to increase, and there was an expansion of the range of solitary males into higher altitudes in years when the population was larger. However, there was no increase in the proportion of solitary males as the total population increased. Furthermore, there was no suggestion that suitable lek habitat was limiting, as the number of leks and the mean size of those leks continued to increase throughout the study period. Although two predictions were supported, the precise patterns of trends, and results of additional analyses, suggested that solitary display is more likely to be an alternative rather than a subordinate tactic. Several factors may promote this apparent dual display tactic in Black Grouse, but habitat structure in this and other Alpine populations is likely to be a key influence. [ABSTRACT FROM AUTHOR]

Climate change is affecting the alpine ecosystem at an unprecedented rate, with marked changes in spring phenology and the elevation distribution of birds. Changes in the European Alps are happening rapidly, and it is possible behaviours stand to change from one year to the next. The year 2022 was characterised by climatic extremes: Italy experienced its hottest year ever, and it was the driest since 1800. Here, we assessed whether the foraging ecology of two coexisting upland bird species, the yellow-billed and the red-billed chough, changed from 2021 to 2022. We assessed foraging stay times, flock size, propensity to mixed flocking, foraging home ranges and altitudinal distribution. Stay times of both species when foraging in monospecific flocks significantly shortened in 2022, especially in the case of the red-billed chough. The two corvids are known to influence each other when foraging together. In 2021, as expected, the stay times of the red-billed chough decreased when in the presence of the congener, but this did not occur in 2022. Instead, the yellow-billed chough increased its altitudinal foraging distribution in 2022. The results are in line with the hypothesis that large climate variations may disrupt the foraging ecology of mountain birds. However, as it is not possible to draw solid conclusions from just two years of observations, further field research will have to be planned in the future., (© 2023. The Author(s).)

The study aims to assess the correlation between dental pathologies and ophthalmic diseases. Based on a statistical evaluation, the study examines the presence of dental diseases in patients suffering from optic neuritis or uveitis in comparison to a control group of subjects. The possible interactions between the two ophthalmic pathologies and dental diseases are then analyzed in order to highlight possible clinical signs which may be useful for their identification.