Evaluación de la capacidad olfativa de las aves marinas para detectar depredadores en las áreas de reproducción: el caso del paíño europeo

Abstract

[eng] Olfaction is a key sense in many animals, from invertebrates to vertebrates, through which they can get information about their environment and carry out different functions. Within birds, seabirds from the order Procellariiformes have an especially developed sense of smell. However, it is unknown whether they can detect potential predators through olfaction or not. Procellariiformes, as other insular organisms, have evolved without predators and are highly vulnerable to introduced predators. Rats are the most introduced invasive mammals on islands where they negatively impact seabirds' breeding success and even adult survival (in small seabirds). In the Mediterranean, black rats were introduced on islands and islets by romans more than 2000 years ago and procellariform seabirds could have enough time to develop antipredatory behaviours. The fact that some seabird species have recently colonized different islands where rats had been eradicated, may indicate the ability of seabirds to detect a safe breeding area. The aim of this project was to experimentally test if the European storm petrel (Hydrobates pelagicus, the smallest European seabird) can detect rats using olfactory cues. We used an Y maze labyrinth with two options of selection: Rattus rattus scent and no scent to test the behaviour of 56 different adult European storm petrels at Benidorm Island. Our results showed that storm petrels did not avoid rat scent: 40% of individuals chose the arm with rat scent and 60% chose the control arm (N=20). Individual characteristics (reproductive experience and body condition) did not influence individual’s behaviour in terms of making a choice or choosing the arm with rat scent. The low percentage of individuals that made a choice was not probably related with a potential freezing response caused by the predator odour. Thus, our results corroborate that European storm petrels are not able to detect black rats through olfaction and confirm the previous evidences found for other bird species which evolved on free-predator islands. Given the extreme vulnerability of insular ecosystems to introduced mammal predators, it is important to raise awareness among society about the importance of keeping the ecosystems free of invasive species and carrying out the corresponding management measures. Moreover, by eradicating rats from islets birds could recolonize new breeding areas and prospectors which visit potential still invaded breeding sites may reduce their mortality probabilities.