Human disturbance may have several negative impacts on bird biology. Although some species may habituate to human presence, other species do not show any signs of habituation, and may even be sensitized or affected by human disturbance. Furthermore, anthropogenic effects on bird behaviour rarely have been explored to address the alteration of frequencies of aggressive and fear-associated behaviours. Such behavioural approaches may provide substantial data for bird conservation and management. Therefore, we assessed whether human disturbance disrupts the normal behaviour of Burrowing Owls Athene cunicularia. Specifically, we assessed whether guarding parents exhibited aggressive and fearful behaviours differentially in areas where human contact was more common. Burrowing Owls showed increased frequencies of threat displays in sites with more people walking by the nests, but not fear behaviours. These results suggest that different domains of behaviour (aggression vs. fear) may respond differently to human disturbance. We highlight the importance of quantifying a wide range of behavioural acts as indicators of bird stress in studies of anthropogenic impact.

∙ Toucans (Ramphastidae) are primarily frugivorous birds that occasionally prey on eggs and nestlings of other birds, often Passeriformes. Here, we report predation events by the Toco Toucan (Ramphastos toco) on eggs and nestlings of the Buff‐necked Ibis (Theristicus caudatus) at the “Buraco das Araras” ecological reserve, Mato Grosso do Sul, central Brazil. At least three of six ibis nests monitored between October 2016 and January 2017 were depredated by the Toco Toucan. In one nest, the single egg was carried to a nearby perch, where the embryo was swallowed completely. In two other nests, the nestlings were 10–15 days old when are depredated. The toucan killed the nestlings by grabbing the head with the beak and shaking vigorously, probably attempting to break the neck. During the attack, the nestlings tried to defend themselves by snapping their bills at the toucan. Once a nestling stopped reacting (dead or dying), the toucan fed on pieces of flesh from the neck. To our knowledge, these are the largest eggs and the heaviest birds preyed upon by toucans. Resumo ∙ Predação pelo tucano‐toco (Ramphastos toco) em ovos e ninhegos de curicaca (Theristicus caudatus) Tucanos (Ramphastidae) são aves tipicamente frugívoras que eventualmente predam ovos e filhotes de outras espé‐ cies de aves, geralmente de Passeriformes. Neste estudo, descrevemos eventos de predação pelo Tucano‐toco (Ramphastos toco) em ninhos da Curicaca (Theristicus caudatus), na RPPN Buraco das Araras, Mato Grosso do Sul, região central do Brasil. Ao menos três dos seis ninhos de curicaca monitorados entre outubro de 2016 e janeiro de 2017 foram predados pelo Tucano‐toco. Em um dos ninhos, o único ovo foi carregado para uma árvore próxima, onde o embrião foi engolido por inteiro. Em dois outros ninhos, os ninhegos estavam com 10–15 dias de vida quando foram predados. O tucano matou os ninhegos agarrando suas cabeças com o bico e agitando‐as vigorosamente, provavelmente tentando quebrar seus pescoços. Durante o ataque, os ninhegos tentaram se defender projetando seus bicos contra o tucano. Assim que as reações dos ninhegos cessaram (mortos ou morrendo), o tucano alimentou‐se de alguns pedaços de carne do pescoço dos filhotes. Ao nosso conhecimento, esses são o maior ovo e a maior ave preda‐ das por um tucano.