Control of the African Sacred Ibis Threskiornis aethiopicus through egg sterilization: preliminary data

As part of the population control project targeting African Sacred Ibis Threskiornis aethiopicus, funded by dedicated MASE resources allocated through the Piedmont Region, the managing authority of the Po Piedmont Protected Areas is implementing interventions to control the species. Among the actions outlined in the Management Plan is the sterilization of eggs through the application of vegetable oils (corn or soybean oil), which prevent embry- onic development. This method, also used in urban and natural environments for other problematic species, is preferred over egg destruction or removal, as it encourages adults to continue incubating, thereby reducing the likelihood of a second clutch. In 2024, a suitable heronry was identified for ground-based intervention, targeting nests up to six meters in height. The interventions, carried out on May 27 and June 11, involved the treatment of 28 nests with 76 eggs (2.7 ±1.12 eggs/nest) and 31 nests with 73 eggs (2.4 ±0.98 eggs/nest), respectively, covering 46% and 70% of the nests detected via drone surveys. The second session followed a new wave of egg-laying. Preliminary results are encouraging, with a hatching rate of approximately 1% in the treated sections of the heronry and prolonged presence of adults continuing incubation behavior. The main limitations of this method relate to the accessibility of the heronry, the presence of other nesting species, and the height of the nests. To overcome these constraints, a specially modified experimental drone was tested, yielding promising results.