Foraging plasticity in Chilean flamingos: influence of water depth, food abundance and intra-flock distances

In a natural context, many avian species exhibit the ability to assess and balance factors such as food availability, food quality, and energy expenditure when making foraging decisions. However, avian behaviours can also diverge from the predictions, influenced by a range of variables, including social behaviours, predation pressures, and individual personalities. Chilean flamingos, popular social birds native to South America, remain relatively underexplored in terms of their foraging ecology and the interplay between environmental conditions and foraging behaviours, especially within the context of conservation. To address this knowledge gap, we conducted a comprehensive study, collecting monthly physical and biological data from foraging flocks of Chilean flamingos at Lagoa do Peixe National Park, a vital contra-nuptial site located in southern Brazil, spanning from October 2021 to September 2022. We employed Generalized Linear Mixed Models to establish correlations between this dataset and the relative frequency and duration of four identified foraging behaviours: Pecking up, Head-dipping, Feet-trembling, and Dredging. Our findings substantiate that the foraging patterns exhibited by Chilean flamingos in this region are intricately linked to the trade-off between energy expenditure and the rewards obtained, primarily influenced by factors such as lagoon depth and the availability of food resources. Moreover, our results unveil a parabolic pattern in the distances maintained between individual flamingos in the flock, potentially attributed to facilitate foraging dynamics within larger groups, despite the concurrent increase in aggressive interactions. In summary, our study underscores the multifaceted variables that influence the foraging strategies of Chilean flamingos in a significant contra-nuptial area in southern Brazil. It sheds light on the behavioural adaptability of these birds and underscores the potential repercussions of this dynamic on individual and population performance and fitness.

• Water depth, food type and food availability are the main variables influencing the foraging behaviors of Chilean flamingo in a natural environment;

• There are a trade-off between energetic reward and energetic expenditure while performing different foraging behaviors;

• The intra-flock distance also influence the foraging behaviors characteristics, with a balance between intraspecific competition and foraging facilitation;