[Transiting species, phenologies and their trends]

[In order to contribute to the knowledge of the spatio-temporal progression of post-nuptial migration of birds across the Italian Alps, we present in detail the results of the analysis carried out for 69 species (4 non-Passeriformes; 65 Passeriformes) of the 191 ringed within the Progetto Alpi. Data were collected in 40 ringing stations located in different habitats and at different altitudes (mountain passes, slopes and valley floors) and active in the post-breeding migratory period (1 August - 30 November). Among these, those (n=15) with continuous activity (at least one month) and known sampling effort (daily capture effort described as product of net area in square meters by operating time in hours) were selected. Data from the 6 stations that operated continuously over the years (2001-2017) and with standardised capture effort were used for trend analyses. Species covered refer to those with more than 100 birds ringed within the first eight hours after sunrise (excluding local retraps). Species accounts contain detailed data from datasets from all stations participating in the Alps Project (1997-2017)]. [Article in Italian]

[A brief history about the ALPI project]

[Conceived by the National Ringing Centre ISPRA and MUSE (Trento, formerly MTSN), the Alps Project was launched in 1997 in order to understand the post-breeding migration strategies of birds across the Italian Alps. The project is realized thanks to the support offered by MUSE and several institutions at a local scale, not to mention the collaboration of over one hundred ringers. In more than twenty years, 40 stations located in sites of passage (alpine and pre-alpine passes) and stop-over (valley floors and slopes) have taken part in the project, leading to a dataset of 666,471 ringed individuals and 191 species (as to 2017). After a first exploratory phase (1997-2002), in which the migration was investigated in its many aspects of specific composition and spatial-temporal variation, the project has been restricted to a smaller number of stations since 2007. Those stations are characterized by working in a standardized and continuous way during the whole period (August-November) or during the migration period of the intra-Palearctic species (end of September-October). In this paper we describe the aims, protocols and organizational aspects of the project, with a special focus on monitoring trends and changes in the long-term phenology. This ongoing project (2021) is part of the ISPRA national ringing plan to monitor bird migration across the country]. [Article in Italian]

Relationship between external weather conditions and number of hibernating bats in two caves in the western Italian Alps

Weather conditions can influence the hibernation behaviour of temperate cave-dwelling bats that are tolerant to low temperatures, and their number can be correlated with weather variables. In this work a first assessment on the correlation between the number of individuals of three species of hibernating bats (Barbastella barbastellus, Myotis emarginatus and Rhinolophus hipposideros) and the environmental weather conditions before the survey was carried out is provided for two hibernacula of the Italian Western Alps. For the B. barbastellus, a significant inverse correlation was observed between the number of bats detected and the average daily temperature for thirty days preceding the count (p= 0.036) and ten days before counting (p= 0.036). A significant positive correlation was observed for M. emarginatus between the number of individuals and the average daily temperatures for thirty days preceding the count (p= 0.018). For R. hipposideros, a significant inverse correlation was observed with the average daily temperatures for the ten days before the count (p= 0.048) and the differences in the maximum and minimum temperature of the ten days preceding the count (p= 0.002). Results of this study show how the ambient temperatures before a count can influence the number of bats present in hibernacula. This confirms how the abundance of bats at underground hibernating sites can be used as an indicator of climate change, as temperature is an important factor controlling hibernation, although further studies are needed in order to better evaluate how the climatic variables interact with each other in regulating the number of bats in the hibernacula.

Temporal trends in abundance and phenology of migratory birds across the Italian Alps during a 20-year period

Introduction: Bird migration across mountainous regions has been studied usually at single sites due to the difficulty in employing and support a multi-site sampling effort. This may affect inference on migration whose scale is larger that a single site. The Progetto Alpi has been monitoring post-breeding bird migration through the Italian Alps with a network of several ringing stations since 1997. Until 2017, 666,471 ringing data of 191 different species were collected. Methods: Phenology of bird migration in terms of date of capture and the related elevational distribution during the sampling season (August-November) were analysed for 69 species. For a subset of 45 species the inter-annual variation in phenology along with trends in the number of ringed birds and in the ratio between the number of juveniles and adults ringed, were also analysed. Results: Migration through the Italian Alps occurred differently between species, with heterogeneity across species in the median date of capture and their elevational distribution. No linear trends in phenology were detected. For four species an annual linear increase of the ringed individuals was detected, while for other four species an annual linear decrease of the captures was detected. For two species, an increase of the ratio between the number of the juveniles and the number of adults ringed was detected. Conclusions: The long-term standardized monitoring of post-breeding migration allowed us to consolidate and increase knowledge of bird migration through Italian southern Alps. The information gathered allowed us to define the temporal and elevation distribution of passerine birds crossing the mountainous area, and to test interannual trends in the number of captures. The main purpose of this work was to report on the information collected in twenty years of field activity, providing a contribution to the understanding this complex phenomenon. Further investigations and more in-depth analyses are necessary to understand how environmental factors and species-specific eco-physiological traits interact and affect migratory strategies of passerine birds in the Italian Alpine region.

Spatio-temporal variability and controlling factors for postglacial erosion dynamics in the Dora Baltea catchment (western Italian Alps)

Disentangling the influence of bedrock erodibility from the respective roles of climate, topography and tectonic forcing on catchment denudation is often challenging in mountainous landscapes due to the diversity of geomorphic processes in action and of spatial/temporal scales involved. The Dora Baltea catchment (western Italian Alps) appears the ideal setting for such investigation, since its large drainage system, extending from the Mont Blanc Massif to the Po Plain, cuts across different major litho-tectonic units of the western Alps, whereas this region has experienced homogeneous climatic conditions and glacial history throughout the Quaternary. We acquired new 10Be-derived catchment-wide denudation rates from 18 river-sand samples collected both along the main Dora Baltea river and at the outlet of its main tributaries. The inferred denudation rate results vary between 0.2 and 0.9 mm/yr, consistent with values obtained across the European Alps by previous studies. Spatial variability in denudation rates was statistically compared with topographic, environmental and geologic metrics. 10Be-derived denudation records do not correlate with the distribution of modern precipitation and rock geodetic uplift. We find, rather, that catchment topography, in turn conditioned by bedrock erodibility (litho-tectonic origin) and glacial overprint, has the main influence on denudation rates. We calculated the highest denudation rate for the Mont Blanc Massif, whose granitoid rocks and long-term tectonic uplift support steep slopes and high relief and thus favour intense glacial/periglacial processes and recurring rock fall events. Finally, our results, in agreement with modern sediment budgets, demonstrate that the high sediment input from the Mont Blanc catchment dominates the Dora Baltea sediment flux, explaining the constant low 10Be concentrations measured along the Dora Baltea course even downstream the multiple junctions with tributary catchments.