This year we have Northern Bald Ibises of the European release population breeding at four different sites. The most established breeding colonies are in Kuchl, Country of Salzburg (AUT), and in Burghausen, Bavaria (GER). On both sites, birds are breeding at six nests. In the newly established breeding colony Überlingen, Baden-Württemberg (GER), this is the second breeding season with a very pleasing number of seven nests. Furthermore, we have a first breeding pair in our newly established breeding colony in Rosegg, Carinthia (AUT).
In Burghausen, 14 chicks already hatched, and further ones may follow. At the other breeding sites, hatching is still ongoing and we have only limited insight into the nests. Thus, we do not know the exact number of eggs resp. chicks. However, according to the data from former years that are currently being published (Drenske et al. in press), we can estimate a mean of 2.5 fledglings per nest, what sums up to 50 fledglings out of 20 nests in this season, compared to 36 fledglings in 2021. This is a great development.
The number of fledglings in our population is significantly higher than in most other wild living or zoo-based Northern Bald Ibis breeding colonies, where data are available (Drenske et al. in press). For example, the last remaining wild population in Morocco only achieves a mean of 1.23 chicks fledged per nest. In our view, this high reproduction rate in the European release population is mainly attributed to a high quality and quantity of feeding sites near the breeding areas. This corresponds to the results of a recently published study (Wehner et al.), where we used GPS data and visual satellite data to model the habitat suitability for the species in the northern Alpine foothills. Areas with a high suitability index largely overlap with historically known and present breeding sites. These studies form an important scientific basis for the reintroduction.
Meanwhile, in Seekirchen am Wallersee, another 31 chicks are growing up in the care of their human foster parents Helena Wehner and Lisa Kern. They have now fledged and will start this week with free-flight training and habituation to the microlight planes that are to guide them to the wintering site in the fall.
Picture: Nests in the artificial wooden breeding wall in Überlingen at Lake Constance. In this June, two to three nests will be transferred to the sandstone cliff along Lake Constance to initiate colonization of the natural structures. This method of nest transfer has been previously carried out at the breeding site Kuchl, with great success. Photo: A. Schmalstieg