Occurrence of Coal Tits Periparus ater during non-breeding seasons in the Great Hungarian Plain

The typically resident Coal Tit Periparus ater, which is widespread in Eurasia, may migrate from breeding sites in large numbers in certain environmental conditions. I used observations from 2005–2023 in a lowland area of south-eastern Hungary to detect irruptive movements of the species. In total, I observed Coal Tits on 258 different days. In some years, they were absent, while in others they occurred in higher numbers. Comparing my data with literature suggests that the birds occurring in south-eastern Hungary are not of the same origin as the birds migrating more regularly through western Hungary. The birds in the study area instead likely originate from the mountainous areas of Romania or the northern Great Hungarian Plain. I found no correlation between the annual numbers of occurrences in south-eastern Hungary and northern Europe, so northern birds likely do not normally enter the Carpathian Basin. However, in 2018, Coal Tits were present in higher numbers in the Great Hungarian Plain as well as in northern Europe, so it is possible that some northern individuals may appear in eastern Hungary during large northern invasions.