Individual features influence the choice to attack in the southern lapwing Vanellus chilensis, but the opponent type dictates how the interaction goes

Abstract

The fight or flight decision (i.e., engage in or evade from an interaction) is one of the most important for animals, occurring in many different ecological contexts and dictating the occurrence of agonistic encounters that could lead to injuries or even death. The southern lapwing Vanellus chilensis is one of the most conspicuous bird species from South America, living in the natural grasslands but frequently found in rural and urban area. The species is known by its typical vocalization and its patterns of aggression and territoriality, considered exaggerated, creating a cultural prejudice towards the species. To better understand the agonistic interaction process in the species, we used general linear models to verify the influence of individual characteristics, environmental characteristics, and opponent features on five different response variables related to the interactions: the time of alert behavior display, probability to attack and evade, total duration of the interaction, and the Behavioral Diversity Index (BDI) of each interaction. Despite the models showing that for each response variables the predictors had different importance and weights, it was possible to note that individual features like age, breeding status, and month impact directly the probability to evade or attack, while the opponent species and distance better explained the other variables related to the interaction. The results also showed that the southern lapwings increase the intensity of responses and sensibility to intruder during the breeding season, displaying a trade-off between self-preservation and the protection of the offspring that is present in other bird species.