Patrones de comportamiento y perfiles de personalidad en el delfín mular (Tursiops truncatus), y su utilidad como herramienta de manejo en cautividad

Abstract

[spa] El objetivo general de esta tesis ha sido estudiar el comportamiento solitario y social de un grupo de ocho delfines mulares (Tursiops truncatus) en cautividad (Zoo de Barcelona), durante dos periodos reproductivos, con el fin de identificar las estructuras de comportamiento y de personalidad, y explorar cómo este conocimiento se puede aplicar para la mejora del bienestar y el éxito de programas de conservación ex situ.

Los objetivos específicos de la tesis han sido los siguientes:

• Explorar la relación entre los patrones de comportamiento y los perfiles de personalidad con el bienestar de los individuos para identificar qué características pueden favorecer una mejor adaptación a la cautividad y ayudar a mejorar su manejo. • Comparar los patrones de actividad en diferentes contextos sociales y ambientales, con el fin de determinar la respuesta comportamental en diferentes contextos a lo largo del tiempo, e identificar aquellos patrones que favorecen el bienestar en condiciones de cautividad. • Investigar y comparar dos metodologías para detectar rasgos de personalidad a partir de observaciones directas de las interacciones sociales: 1) un análisis de patrones temporales multivariado, y 2) un análisis de reducción de dimensiones, con el fin de identificar rasgos de personalidad de la especie y evaluar la efectividad de cada metodología para conseguir este propósito. • Identificar la relación directa entre comportamientos observados y adjetivos que describen rasgos de personalidad, comparando dos diferentes metodologías de evaluación de personalidad, a través de: 1) observaciones directas (“codings”), y 2) calificaciones indirectas de adjetivos (“ratings”), con el fin de identificar la estructura de personalidad y validar para ella la metodología de “codings”.

[eng] The study of solitary and social behavioral patterns of animals under human care is useful for management practices, as the impacts of all the experiences perceived and expressed by individuals represent their welfare states. As animal welfare depends on how an individual copes with its living conditions and challenges, the identification of personality profiles contributes to a better understanding of individual needs and can be used to guarantee optimum welfare. Animal personality is defined as the behavioral differences between individuals of the same species, which are consistent over time and across contexts. Despite there is a great number of studies on activity budgets in cetaceans, few have established the range and threshold of frequent behavioral patterns, that are indicative of welfare states. There are also studies in cetacean personality, but very few have determined the correspondence between behavioral measures and questionnaire-based assessments, aiming at determining personality. The main objective of this thesis was to study the solitary and social behavior of a group of eight bottlenose dolphin (Tursiops truncatus) in captivity (Barcelona Zoo), during two reproductive cycles, to identify the behavioral and personality structures of the species, and explore how this knowledge can be used to improve welfare and success in ex situ conservation programs. Ethological observations were made during nine different reproductive stages, to study behavioral patterns in different environmental and social contexts, and detect personality structures. The proportion of behaviors that the study subjects engaged in solitary and interindividual interactions during their daily activity patterns, were explored using all-occurrence continuous follow sampling bouts and instantaneous scans. Behavioral structure was explored using a multivariate temporal pattern (T-pattern) analysis and personality structure was identified using a dimension reduction analysis. Both methods were then compared to test their effectiveness in identifying personality traits in social mammals. Two personality assessment methodologies, observed interactions (known as “codings”) and ratings of adjective items (known as “ratings”), were used and then compared, to validate the “codings” methodology for the species. Different social contexts significantly modulated mean frequencies of solitary and social behaviors. Findings suggest that the most frequent behaviors out of the total visible activity budget were solitary swimming (18% - 28%), close swimming (20%) and maternal close swimming (20% - 42%). Behavioral structures varied according to context, as structures were more complex during the pre-natal phase, suggesting that

endocrine and physiological changes during the advanced pregnancy stage may modulate behavioral patterns of mothers. Expectant females seemed uncomfortable during the pregnancy stage, possibly due to an inappropriate birthing environment, but their relationship improved when their calves were born. We found that a better approach to assess personality profiles is achieved by inferring dimensions, rather than studying multivariate T-patterns. In total, four personality factors were identified in this investigation: Extraversion, Agreeableness, Neuroticism and Conscientiousness. The factors inferred with both personality assessments correlated statistically and traits grouped similarly, which validates the “codings” methodology used in this investigation. Bottlenose dolphins exhibit different behaviors, even having equal characteristics like sex, age group, birth type, reproductive status, and living under the same environmental conditions and social groupings. This suggests that subjects respond in different ways to the same experiences, which is why it is useful to have knowledge of the personality of individuals, to predict their responses and to know the characteristics that help their adaptation to changes and living conditions in captivity. With this, we conclude that personality is a useful tool to improve the management of bottlenose dolphins under human professional care and to determine the social conditions that guarantee welfare and breeding success, which are crucial for ex situ conservation programs of endangered species.