Sibling pairing within Jackdaw colonies

Abstract

During the period from 2014 to 2019 Jackdaws Corvus monedula had been ringed and observed intensivly in the town of Neumünster, Schleswig-Holstein. Overall 1410 birds could be ringed. For the first time, two siblings ringed in 2014 were observed as a pair in 2015. The birds had wintered in the breeding area. In 2016 they were observed together during feeding. In 2017 they raised young again and at least one had been ringed, too. They continued their breeding behavior togehter in 2018 and 2019. Besides this long observation a second sibling pair for the years 2017 to 2019 established, without registered offspring. And such a third pair might be present since 2017, although the data situation is weak. We conclude sibling mating might happen more often than assumed until now. An influence of the many nest boxes (n = 150) on this finding cannot be excluded.