First confirmed breeding of an invasive alien species in the lagoon of Venice (Italy): the Sacred Ibis Threskiornis aethiopicus

Abstract

After more than a decade of regular occurrence, the first confirmed breeding of the Sacred Ibis Threskiornis aethiopicus in the lagoon of Venice (Italy) was observed in 2020, in three sites. The ibises nested in colonies with of one or more species of Ardeidae and Phalac-rocoracidae. The colonies were on islets < 2 ha in size, covered with thick vegetation. Nests were placed on the top of bushes or trees, at a height of 1.5-5 m. The colony sites seemed not occupied by adults until the end of February-half of March; laying took place from early May, with hatchings occurring from the end of that month until July. Overall, 22-24 pairs nested in 2020. Birds were observed feeding at saltmarshes, freshwater wetlands and arable fields; a public garbage collection site was also used regularly. Given the high number of suitable nesting and feeding sites, a rapid growth of the Sacred Ibis population is expected in the next years.