Recent anthropogenic global changes (alteration of habitats and climate change) threaten the conservation of biodiversity. This is the case of migratory birds that live in intensely cultivated agricultural areas. Species distribution models give insights on the factors that determine the distribution of wild species at wide spatial scales, and are important tool for wildlife conservation. Lesser kestrel (Falco naumanni) is used here as a model species: this small migratory falcon breeds in Southern Europe farmlands. This species was extremely common until the mid-XX century, then suffered a population collapse in the 60s-70s, and only after the year 2000 the population has recovered. The species is included in Annex I of Directive 79/409/EEC “Birds”. Due to global climate change, the lesser kestrel is expanding its range to northern latitudes, and now the breeding colonies in Po Plain represent the northernmost limit of the breeding range in Europe. This study has been realized in the context of the “LIFE FALKON” project activities. The objectives of this work are 1) to update the population status of lesser kestrel in the Po Plain 2) to study the land-use and climatic factors that determine its current distribution in the area through species distribution models 3) to realize future projections of this distribution as determined by climate change 4) to assess whether the current distribution of the Natura 2000 network is effectively protecting or not the population of the Po Plain. An extensive field-based census of all the potentially suitable buildings for breeding was carried out during the 2019 in the project LIFE study area. In total, now we know 23 active colonies in Po Plain. A series of climatic and landscape variables were used, together with the land use data of the CORINE Land Cover to build up species distribution models for the species. A series of distribution models of lesser kestrel were then realized, using three different algorithms (MaxEnt, GLM, Bioclim). I observed that the species favoured dry-continental climates with low rainfall and high temperature seasonality, and selected intensive cultivation farmland habitats. Other landscape elements, such as woods, wetlands, lakes and rivers, extensive crops, are instead avoided by the species. The most robust distribution model (MaxEnt) was then used to make different projections for the future for 2050 and 2070 under different scenarios of climate change intensity (RPC scenario 4.5 and 8.5) and using two types of predictive models (BCC-CSM1-1 and GISS-E2-R). Almost all the projections concur in show an expansion of the suitable breeding distribution, which is also predicted to shift towards north-east. The progressive urbanization may will pose the main limit to the future expansion. Comparing the distribution of the Natura 2000 network of protected areas and the potential breeding area of the species, I found that that SCIs and SPAs currently represent an ineffective tool for the protection of the species, guaranteeing less than 6% of the suitable protected territory. My results suggest that it is advisable to program a long-term monitoring of lesser kestrel in the Po Plain, in order to collect fundamental information on the distribution of the species and eventually program proper conservation actions. The agricultural management emerge as a crucial factor determining the occurrence of lesser kestrel in the Po Plain, as well as the urbanization is instead its major threat factor.
Le modifiche antropiche globali (alterazione degli habitat naturali e cambiamenti climatici) minacciano seriamente la conservazione della biodiversità. Un esempio riguarda gli uccelli migratori degli agroecosistemi, in cui forme di tutela entrano in conflitto con le esigenze economiche. I modelli di distribuzione delle specie rappresentano un importante strumento per consentire la loro corretta conservazione Si è utilizzata come specie modello il falco grillaio (Falco naumanni), un piccolo rapace migratore che si riproduce negli habitat agricoli dell’Europa Meridionale. Questa specie, un tempo comune, ha subito un grave declino nel secolo scorso, e vede una ripresa solo dopo il 2000. La specie è inserita nell’Allegato I della Direttiva 79/409/CEE “Uccelli”. Recentemente, anche a causa dei cambiamenti climatici, il grillaio si sta espandendo verso nord, e le colonie in Pianura Padana rappresentano oggi la popolazione più settentrionale dell’Europa Occidentale. La presente tesi è parte del progetto LIFE FALKON, che ha come obiettivo quello di favorire la conservazione delle popolazioni di grillaio al margine nord del suo areale. Gli obiettivi di questo lavoro sono stati 1) aggiornare lo stato della popolazione del grillaio in Pianura Padana 2) studiare come i fattori climatici e di uso del suolo determinino l’attuale distribuzione delle specie nell’area, con modelli di distribuzione 3) realizzare proiezioni future di questa distribuzione in un contesto di cambiamenti climatici 4) valutare l’efficacia della protezione di Rete Natura 2000 in Pianura Padana. Nel 2019 è stato effettuato un censimento di tutti gli edifici potenzialmente idonei per la nidificazione all’interno dell’area di studio del progetto LIFE. In totale, si è arrivati alla conoscenza di 23 colonie attive in Pianura Padana. Si sono poi selezionate variabili ambientali climatiche (Bioclimatic del database WorldClim) e i dati di uso del suolo del progetto CORINE. Si sono realizzati tre modelli di distribuzione potenziale della specie (mediante tre algoritmi di calcolo differenti: MaxEnt, GLM e Bioclim), per studiare i fattori determinanti la distribuzione e ottenere altrettante mappe di idoneità ambientale. Si è osservato come la specie tenda a favorire ambienti dal clima continentale-secco (con basse precipitazioni e alta stagionalità secondo le temperature), selezionando habitat agricoli costituiti da coltivazioni intensive. Elementi come boschi, aree umide, corpi d’acqua, coltivazioni estensive, sono invece evitati. Utilizzando il modello più robusto (MaxEnt) si sono effettuate le proiezioni future. Si sono scelte 2 diverse tipologie di intensità di cambiamenti climatici (scenario RPC 4.5 e 8.5) di 2 modelli predittivi (BCC-CSM1-1 e GISS-E2-R) per gli anni 2050 e 2070, mentre sono state mantenute le variabili di uso del suolo. Le protiezioni mostrano un ampliamento dell’areale idoneo di nidificazione, che, tenderà a spostarsi verso il Mar Adriatico. Un limite dell’espansione potrebbe essere causato dall’aumento dell’urbanizzazione del territorio. Confrontando Rete Natura 2000 con l’area di nidificazione potenziale, si è osservato come SIC e ZPS rappresentino uno strumento inefficace per la tutela della specie, garantendo meno del 6% del territorio idoneo salvaguardato. Sfruttando i modelli realizzati nel presente studio si propone di continuare la ricerca delle colonie in Pianura Padana, individuando nuovi siti di presenza per una corretta tutela della specie. La gestione agricola è il fattore cruciale che determina la presenza del grillaio in Pianura Padana, mentre l’urbanizzazione rappresenta il principale fattore di minaccia.
STUDIO DEI FATTORI DETERMINATI LA DISTRIBUZIONE PRESENTE E FUTURA IN PIANURA PADANA DEL GRILLAIO (Falco naumanni) E IMPLICAZIONI CONSERVAZIONISTICHE
BERLUSCONI, ALESSANDRO
2018/2019
Abstract
Recent anthropogenic global changes (alteration of habitats and climate change) threaten the conservation of biodiversity. This is the case of migratory birds that live in intensely cultivated agricultural areas. Species distribution models give insights on the factors that determine the distribution of wild species at wide spatial scales, and are important tool for wildlife conservation. Lesser kestrel (Falco naumanni) is used here as a model species: this small migratory falcon breeds in Southern Europe farmlands. This species was extremely common until the mid-XX century, then suffered a population collapse in the 60s-70s, and only after the year 2000 the population has recovered. The species is included in Annex I of Directive 79/409/EEC “Birds”. Due to global climate change, the lesser kestrel is expanding its range to northern latitudes, and now the breeding colonies in Po Plain represent the northernmost limit of the breeding range in Europe. This study has been realized in the context of the “LIFE FALKON” project activities. The objectives of this work are 1) to update the population status of lesser kestrel in the Po Plain 2) to study the land-use and climatic factors that determine its current distribution in the area through species distribution models 3) to realize future projections of this distribution as determined by climate change 4) to assess whether the current distribution of the Natura 2000 network is effectively protecting or not the population of the Po Plain. An extensive field-based census of all the potentially suitable buildings for breeding was carried out during the 2019 in the project LIFE study area. In total, now we know 23 active colonies in Po Plain. A series of climatic and landscape variables were used, together with the land use data of the CORINE Land Cover to build up species distribution models for the species. A series of distribution models of lesser kestrel were then realized, using three different algorithms (MaxEnt, GLM, Bioclim). I observed that the species favoured dry-continental climates with low rainfall and high temperature seasonality, and selected intensive cultivation farmland habitats. Other landscape elements, such as woods, wetlands, lakes and rivers, extensive crops, are instead avoided by the species. The most robust distribution model (MaxEnt) was then used to make different projections for the future for 2050 and 2070 under different scenarios of climate change intensity (RPC scenario 4.5 and 8.5) and using two types of predictive models (BCC-CSM1-1 and GISS-E2-R). Almost all the projections concur in show an expansion of the suitable breeding distribution, which is also predicted to shift towards north-east. The progressive urbanization may will pose the main limit to the future expansion. Comparing the distribution of the Natura 2000 network of protected areas and the potential breeding area of the species, I found that that SCIs and SPAs currently represent an ineffective tool for the protection of the species, guaranteeing less than 6% of the suitable protected territory. My results suggest that it is advisable to program a long-term monitoring of lesser kestrel in the Po Plain, in order to collect fundamental information on the distribution of the species and eventually program proper conservation actions. The agricultural management emerge as a crucial factor determining the occurrence of lesser kestrel in the Po Plain, as well as the urbanization is instead its major threat factor.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
Per maggiori informazioni e per verifiche sull'eventuale disponibilità del file scrivere a: unitesi@unipv.it.
https://hdl.handle.net/20.500.14239/22213