Observations on parental care of the Eurasian Spoonbill (Platalea leucorodia) during the post-fledging dispersal

Abstract

Abstract The number of available publications on the post-fledging parental care of wading birds (herons, ibises, spoonbills, and storks) and many other bird species is limited. In this study, I summarised the available knowledge collated from the observations of the Eurasian Spoonbills (Platalea leucorodia) in Hungary. A part of the available data is based on observations of colour-ringed individuals. The latest feeding event of a young by its parent was observed at Lake Csaj on 5 October 2020. The youngsters were being fed by their parents for 43 days (observed maximum) during the post-fledging dispersal. However, I estimated that this behaviour could even last for as long as 53 days. The parents lead (care for) their yearlings for 51 days (observed maximum), again I estimated that it could potentially last for a longer period of 63 days. The estimated length of parental care and feeding period could be longer or a little bit shorter during the post-fledging dispersal because it was not possible to follow the life of the families exactly. During parental care (feeding and leading of chicks), the majority of the colour-ringed Spoonbills were observed 2–26 km to the natal colonies of yearlings and the breeding colonies of the adults. However, on some occasions, they were 111–145 km far from those colonies. During the post-fledging dispersal, Spoonbills care for their chicks for a longer time than the European breeding heron species. A possible reason could be that the bills of young Spoonbills are not appropriate for fishing effectively at the beginning of fledging because of their shorter length and their less efficient hydrodynamic effect during lateral sweeping. Another reason could be that Spoonbills are tactile foragers and need more time to learn fishing. Based on data of a juvenile followed by a GPS device, learning the migration route and stop-over sites from parents or experienced adults could be important for Spoonbills, otherwise, young migrating alone with no accomplished individuals may not find the optimal routes and the proper stop-over areas. In the case of Spoonbills, we still do not know exactly the features of parental care during the post-fledging dispersal and have even less data on it during the migration. Thus, I request potential observers along the Adriatic Flyway to record the observations of parent-offspring interactions (feeding by parents, begging) particularly the Hungarian colour-ringed adults and/or young individuals and send data to the author’s e-mail address.