26:T4db,

Human activities, including ecotourism and research, can significantly impact wildlife behaviour during reproductive season, yet their effects are often underestimated. We conducted a study on psittacines in the Cerrado of Concepción, Paraguay, during the breeding season, focusing on responses to human presence. A total of 232 observations of nine psittacine species were recorded, with varied behavioural responses to human activities. Larger species exhibited higher flight initiation distances (FID), reflecting possible increased sensitivity. Notably, ecotourism and cavity monitoring correlated with birds flying away, emphasizing potential negative impacts. Conversely, activities like counting and remote photography showed positive correlations with relaxed avian behaviours. Our findings highlight the importance of considering human activities' nuances, especially during critical periods like breeding seasons, to minimize disturbance and promote coexistence with wildlife. Further studies are needed to understand behaviour better and we recommend adopting precautionary measures, such as limiting interventions during sensitive reproductive phases, to contribute to the well-being and conservation of psittacine species.

27:T484,

Sexual size dimorphism (SSD) commonly occurs in birds, with males typically larger than the females. One notable exception is the family Alcedinidae, which displays moderate reverse SSD. Using body mass data collected from birds hatched at Brookfield Zoo Chicago between 1989-2023, we confirm that the sihek (Guam kingfisher, Todiramphus cinnamominus) exhibits moderate reverse SSD. Female chicks are significantly larger than males at fledging (t = 4.23, df = 23.33, p = 0.003). Adult birds 50 days and older display significantly different body masses, with females weighing on average 7% more than males (t = 3.20, df = 49.91, p = 0.00238). We assessed the growth patterns of male and female sihek chicks using logistic nonlinear mixed models and found that the null model was a better fit (lower AIC); therefore, there was no significant difference between the growth parameters for each sex from hatch through forty days. These results contribute to the body of work investigating the evolution of SSD in birds and provides data on the growth and development of an extinct-in-the-wild species.

28:T64d,