How can the stork bring the baby? An evaluation of captive saddle-billed stork reproductive activity and influences of husbandry practices

Husbandry surveys can be useful evidence gathering exercises that enable the formulation, and implementation, of better practice care for species in zoos. Where ecological or behavioural needs of a species can be hard to replicate, or when they experience limited successful reproduction, husbandry surveys can illuminate key elements of good practice from across facilities to meet these challenges and support the development and management of sustainable populations. The saddle-billed stork ( Ephippiorhynchus senegalensis ) is one example of a challenging species to maintain under human care, with limited successful reported breeding (egg laying, chick rearing and fledging of young). Therefore, research aimed to survey holders of this stork to identify factors influencing reproductive success across AZA and EAZA regions. We found that wild-caught pairs produced significantly more clutches than captive-bred pairs, while flight restriction appeared to negatively impact fertility rates. All successfully breeding pairs exhibited courtship behaviours, though these behaviours alone did not guarantee reproductive success. Whilst a single nesting platform appeared more effective than multiple or no platforms in encouraging nesting, no single demographic, environmental, or husbandry factor significantly predicted egg-laying success. This suggests that successful reproduction depends on complex interactions between multiple variables. Our findings highlight the importance of providing appropriate environmental conditions that support natural behaviours and emphasise the need for a holistic approach to exhibit design for successful breeding of this species in zoological collections. We recommend further research into the ecology of the species itself, especially mate choice and pair bonding mechanisms, to further evaluate variability in zoo-housed stork reproductive efforts. • Wild-sourced saddle-billed storks produced more clutches than captive-bred pairs. • Flight restriction negatively affected fertility. • Single nesting platforms were more effective for nesting than multiple or no platforms. • All successfully breeding pairs exhibited courtship behaviours. • Overall, no single demographic, environmental, or husbandry factor predicted egg-laying success.