Reintroduced White Storks (Ciconia ciconia) have similar diets to their wild conspecifics, suggesting conservation translocation success

Understanding a species' diet is crucial for assessing its ecology and can indicate the success of reintroduction efforts. We explored dietary composition and compared pellet morphology and supplementary food proportions between two white Stork (Ciconia ciconia) groups to assess reintroduction effectiveness. White Stork groups consisted of released free-flying individuals and those kept within a confined enclosure. A total of 23 white Stork pellets were collected during the 2023 breeding season. Pellets from free-flying individuals were significantly heavier (x̄ = 12.74 ± 9.23g [SD]) than pellets from enclosed individuals (x̄ = 5.15 ± 2.11g). As expected, pellets from enclosed individuals consisted mostly of supplementary food, accounting for 91% of pellet biomass. Whereas c. 60% of pellets from free-flying individuals contained supplementary food, comprising 53% of pellet biomass. The flying individuals predominantly foraged on beetles (Coleoptera) and earthworms (Clitellata). Our results represent the first quantitative dietary assessment of reintroduced White Storks in southern England. Similarities between our data and that of white stork diets from elsewhere in their range suggest successful post-release acclimatisation at Knepp Estate.