A prestigious research project reveals the effects of climate change on the population of Rock Sparrows in the Upper Susa Valley

According to Cipra, the International Commission for the Protection of the Alps, in the last 120 years, temperatures in the Alpine regions have risen by about 2 degrees Celsius, nearly twice the global average. The Alpine arc, being a sensitive ecosystem, is particularly affected by the impacts of climate change, evidenced by the progressive melting of glaciers, the decrease and seasonal shift of precipitation, the increase in extreme weather events, and noticeable effects on flora and fauna.

Recently, an article by Toni Mingozzi, Pierpaolo Storino, Giampalmo Venuto, Alessandro Massolo, and Giacomo Tavecchia was published in the scientific journal Current Zoology, focusing on the effects of climate warming on the breeding season of the Rock Sparrow (Petronia petronia) at its altitudinal limits: Climate warming induced a stretch of the breeding season and an increase of second clutches in a passerine breeding at its altitudinal limits.

The study is part of a project led by the Department of Biology, Ecology, and Earth Sciences of the University of Calabria in collaboration with other European universities and the University of Calgary, which directly involved the staff of the Val Troncea Natural Park and more recently the Cozie Alps Parks.

Evaluating the influence of climatic and landscape variations on population dynamics, trophic strategy, local survival, and dispersal are the primary objectives of the research.

The "Petronia Project," initiated in 1988, fully operational by 1991, and concluded in 2013, has proven to be one of the most prestigious and enduring long-term research projects in Italy.

Over 22 years, precise and continuous data on the presence and nesting phases of the species have been collected. The species is still monitored by the Park Authority and has proven to be an excellent study model for investigations aimed at both pure research (eco-ethological) and conservation and management of mown meadows related to priority habitats cod. 6210 and 6520 of the Special Conservation Zone IT1110026 Champlas Colle del Sestriere.

The study population is located in the upper Susa Valley, covering an area of about 13 km2 on the south-southwest slope in the municipalities of Sestriere and Cesana Torinese, between 1350 and 2000 meters above sea level near San Sicario, Champlas Janvier, Champlas Seguin, and, more recently, Champlas du Col and Thures. The territory is characterized by xeric pastures and mountain meadows, which have experienced a drastic reduction in traditional agro-pastoral practices (cultivation of fields, livestock farming, and hay mowing) in recent decades, leading to the risk of modification of herbaceous communities, invasion by shrubs and trees, and loss of the high level of plant and animal biodiversity associated with mown and grazed meadows.

The Rock Sparrow (Petronia petronia) is a passerine bird of the Passeridae family distributed in southern Europe. It is omnivorous, feeding on seeds and insects. Male and female birds are practically identical in appearance; the clear eyebrow and the striking yellow spot on the throat distinguish it from other passerines.

It inhabits open environments, in dry and sunny conditions. In the Western Alps, it breeds in some internal valleys (in continental xeric sectors), in small and isolated populations at the altitudinal limits of its European range.

The monitoring area hosts the most significant population in northern Italy; the species, typically Mediterranean, is also sporadically reported in Cuneo and in Aosta Valley, but it is characteristic of southern Italy.

This population has been identified as a good model for assessing the effects of climatic variations. In these environmental conditions, reproductive parameters and performance have demonstrated greater susceptibility to temperature and precipitation variations compared to less marginal and more favorable sites for the species.

Being gregarious, it reproduces at the edges of mountain villages, where it prefers to build its nests in deep holes in dilapidated buildings, without eschewing cavities in trees and among rocks.

To monitor nesting phases, nest boxes specifically designed to meet the species' needs (dimensions of 11x12 cm and 50 cm in depth with an oval entrance hole of 5x3 cm) were installed on poles and could function as capture devices when necessary for scientific purposes. Birds have shown a marked preference for nest boxes over natural nests. As a result, since 1994, all known natural nests have been abandoned, and presumably the entire population has begun nesting in the nest boxes.

During the period 1991-2013, the occupancy status of the nest boxes was regularly monitored from mid-May to early September throughout the nesting season (from nest building to fledging).

Ringing, carried out by park rangers authorized by the ISPR, has been one of the key operations of the project, aimed at individual recognition of the subjects comprising the study population. All breeding adults and chicks were individually marked with colored rings to recognize the animals and ascertain social and pair bonds through direct observations.

Over 22 years of the project, a total of 2802 birds (228 adults and 2574 chicks) were ringed, and 633 broods, including first and second annual broods, were recorded.

The results of the study confirm that climate changes in the Alps favor the Rock Sparrow, ensuring higher breeding success of the broods and the average number of fledglings and a longer breeding period. Following the confirmed rise in July temperatures, an increase in the frequency of second broods was also observed.

The data indicate that the Rock Sparrow did not advance the start of the breeding season, although this has been reported as one of the most common responses of living organisms to recent climate change.

In general, an increase in occupation rate and/or colonization of new areas is expected. However, extreme weather events in recent years, especially intense summer precipitation, have proven to be a serious threat to the survival of the broods.