Management and reproductive parameters of a captive scarlet ibis (Eudocimus ruber) population at low latitude

Effective captive breeding programs are essential for conserving threatened avian species. This study aimed to describe the breeding performance of a captive population of scarlet ibis over a three-year period (2022, 2023, and 2024). The breeding season varied between July and January over the three years. Both males and females began forming breeding pairs as early as two years old, with the oldest pairing ages being 20 years for males and 12 years for females. Higher enclosure densities appeared to improve laying rates and encourage earlier laying, while a 1:1 male-to-female ratio facilitated effective pair formation with minimal aggression. Egg removal led to an average of 7.6 ± 2.7 replacement lays per female. Advancement of the laying season was significantly associated with increased initial egg weight for Dezember (p < 0.01). The median daily weight loss during incubation was 0.7 % (tau = 0.5), while the mean weight loss on day 21 was 19 ± 2 %. The findings from this study are relevant to enhance the efficiency of breeding programs for the species and may inform breeding strategies for other species within the Threskiornithidae family.