Questa tesi rappresenta il risultato di indagini effettuate tra il 2016 ed il 2019 sulla distribuzione della civetta nana (Glaucidium passerinum) in Valle di Susa, situata nelle Alpi occidentali italiane. Per questo censimento sono stati realizzati due modelli di distribuzione della specie, mediante il software MaxEnt. Il primo è stato ricavato a partire da 12 punti relativi ad individui territoriali rilevati mediante la tecnica del playback, utilizzata durante il periodo riproduttivo in due aree campione indagate, incluse in due aree protette facenti parte dell' Ente di Gestione dei Parchi Alpi Cozie. Successivamente è stata validata la presenza della specie in alcune aree indicate altamente idonee da questo modello, permettendo di rilevare complessivamente la presenza di 25 maschi territoriali per l'intera vallata durante il periodo di studio, osservati ad una quota variabile tra i 1450 e i 2035 m. Questi dati confermano la sottostima ipotizzata da alcuni autori per questo settore alpino e sembrano in linea con l'espansione della specie rilevata di recente in altre aree alpine. Data l'elevata efficienza di un secondo modello realizzato con le osservazioni complessive, espressa da un AUC di 0.986, sono stati descritti gli ambienti e le superfici maggiormente vocati per la specie. La selezione dell'habitat della civetta nana in Valle di Susa è risultata fortemente legata all'esposizione prevalente a Nord dei versanti occupati, ad alcune tipologie forestali di conifere miste e ad una distanza breve da aree aperte. Questi risultati differiscono in parte da quanto riportato in bibliografia, forse trattandosi questo del primo studio effettuato esclusivamente durante il periodo riproduttivo della civetta nana per le Alpi occidentali italiane.
This thesis represents the result of investigations carried out between 2016 and 2019 on the distribution of the Eurasian pygmy owl (Glaucidium passerinum) in the Susa Valley, located in the Italian western Alps. For this census, two species distribution models were made, using the MaxEnt software. The first was obtained from 12 points relating to territorial individuals detected by using the playback technique, during the reproductive period in two sample areas of survey, incused in the protected areas of the Cottian Alps Parks Management Authority. Subsequently, the presence of the species was validated in some areas indicated as highly suitable by this model, allowing the overall detection of 25 territorial males for the entire valley during the study period, observed at variable altitude between 1450 and 2035 m. This data confirms an underestimation already hypothesized by some authors for this alpine sector and seems in line with an expansion of the species recently detected in other alpine areas. Given the high efficiency of a second model made with the overall observations, expressed by an AUC of 0.986, the most suitable environments and surfaces for the species have been described. The habitat selection of the Eurasian pygmy owl in Susa Valley was strongly linked to the prevailing exposure to the North of the mountainsides, to some types of mixed coniferous forests and to a short distance from open areas. These results a little different from what is reported in the bibliography, perhaps this study being the first carried out exclusively during the reproductive period of eurasian pygmy owl for the Italian western Alps.
Distribuzione della civetta nana (Glaucidium passerinum) in Valle di Susa
ANSELMO, LUCA
2018/2019
Abstract
This thesis represents the result of investigations carried out between 2016 and 2019 on the distribution of the Eurasian pygmy owl (Glaucidium passerinum) in the Susa Valley, located in the Italian western Alps. For this census, two species distribution models were made, using the MaxEnt software. The first was obtained from 12 points relating to territorial individuals detected by using the playback technique, during the reproductive period in two sample areas of survey, incused in the protected areas of the Cottian Alps Parks Management Authority. Subsequently, the presence of the species was validated in some areas indicated as highly suitable by this model, allowing the overall detection of 25 territorial males for the entire valley during the study period, observed at variable altitude between 1450 and 2035 m. This data confirms an underestimation already hypothesized by some authors for this alpine sector and seems in line with an expansion of the species recently detected in other alpine areas. Given the high efficiency of a second model made with the overall observations, expressed by an AUC of 0.986, the most suitable environments and surfaces for the species have been described. The habitat selection of the Eurasian pygmy owl in Susa Valley was strongly linked to the prevailing exposure to the North of the mountainsides, to some types of mixed coniferous forests and to a short distance from open areas. These results a little different from what is reported in the bibliography, perhaps this study being the first carried out exclusively during the reproductive period of eurasian pygmy owl for the Italian western Alps.| File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14240/100529