Assessing saddle‐billed stork (Ephippiorhynchus senegalensis) pair‐bonds and breeding behavior using behavior observed during multiple breeding seasons

Abstract

Despite the fact that saddle-billed storks (SBS) are housed in zoos around the world, few successful hatches have been recorded. At Disney's Animal Kingdom® we conducted observations on two pairs of SBS during multiple reproductive periods to assess the relative strength of their pair-bonds and their reproductive success. We accomplished this through observations of rates of social behaviors, such as wing displays and aggression, rates of nest construction, time on and near the nest, and egg production. We determined that one pair was more successful than the other because it produced and incubated eggs during all breeding seasons. We found that the male from this more successful pairing displayed higher rates of nest presence, nest construction, and time on the nest than all other individuals. The more successful pairing also spent more time in close proximity than the less successful pair. During incubation, the male and female from the more successful pair spent similar amounts of time at the nest and incubating the eggs, but this pair never successfully hatched an egg during our study period. Ultimately, our results suggest that the pair-bond between the more successful pair was stronger than that of the other pair because they spent more time in close proximity and performed higher rates of nesting behaviors. This study highlights the lack of understanding of the factors that lead to successful SBS pairings in zoos, and emphasizes the need for future studies of their nesting behavior and pair compatibility to increase reproductive success.