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[The paper shows the evolution of the breeding distribution of the Ashy-headed Wagtail Motacilla flava cinereocapilla in the period 1820-2014. Until 1880, the subspecies nested along the coast north and east of the Adriatic Sea, with some settlements (probably of poor numerical consistency) located in suitable areas of Tuscany, Sicily and Provence; after 1880 it was observed to appear regularly in the Po Valley during migration, and afterwards to occupy the area widely as a breeder. During the nineteenth century the Po Valley underwent major transformation processes with the consequent disruption of ancient agricultural rotations, and an increase of 1°C in the average temperature was also recorded in the area. Out of all the changes that occurred, besides the abundant availability of water, the biotic factor that probably favored the expansion of the subspecies in the Po valley the most is the increase in livestock and the consequent increase in the meadowlands: the first mowing of grass coincides temporally with the hatching of yellow wagtails (often nesting in neighboring fields of wheat), offering them the opportunity to increase the efficiency and effectiveness of foraging on the open ground, with likely benefits for the reproductive success. In the first half of the twentieth century the Ashy-headed Wagtail completed the occupation of the Po Valley, and in the late 1940 a new phase began, during which it settled in new areas in central and southern Italy and Sardinia, extending its distribution area in southern France; but, above all, appearing with increasing frequency and regularity during migrations north of the Alps. These northward shifts later materialized in the settlement of several reproductive groups in France, Switzerland, Germany and Austria, always along basins of rivers or near lakes. Water seems to be the catalyst for the presence of the subspecies. This further expansion phase has probably been favored by climate changes, and in particular by the rise in temperature in the Greater Alpine Region. Favoured by this situation, the subspecies has also colonized mountain areas: in France up to 350 m.a.s.l. in the department of Isère, in Switzerland up to 1700-1800 m.a.s.l. in the Upper Engadine, in Germany up to 880 m.a.s.l. at Ammer and Grunt lakes, in Austria up to 960 m.a.s.l. in Hochfilzen and in Bosnia-Herzegovina up to 720 m.a.s.l. in the plain of Livanjsko. In the Italian Alps it reached the altitude of about 900 m.a.s.l. in Venosta Valley and up to 1000 m.a.s.l. in central Apennines. Since the last decades of the twentieth century nestings have been recorded in Spain. Instead, the breeding of the subspecies in Maghreb is still uncertain.]