Christina Lehmkuhl Noer:
Conservation-breeding programs in zoos are essential for the management of threatened species. By moving animals amongst institutions for prescribed breeding, these programs aim to promote demographic stability and preserve genetic variation in the captive populations. Yet many breeding programs are unsustainable. Often, prescribed pairs of animals appear to be incompatible and reproductively unsuccessful. This is also a problem in solitary carnivore species, many of which are threatened with extinction. A suggested solution to this problem is to investigate, which male cues and signals the females use to assess mate quality before making their mate choice, and then introduce these cues and signals from different males to the female prior to introduction of a mate. Females have the ability to determine the male to which they are genetically better matched among available options and studies of the outcomes of mate choice suggest that choosy females benefit from increased fecundity, litter size, and offspring survival. Thus, providing females with the opportunity to choose from several males might improve the sustainability of captive populations.
The main objective of this thesis is to develop and test a method to assess female preference using selected male signals and cues and to investigate whether this preference translates into a mate choice. Due to their biological relevance, and because research has proved their importance in other species’ mate assessment, I focus on three signals or cues: olfactory (urine and faeces), size, and behaviour. The latter may represent aspects of animal personality. The background for this is explained in the introduction (Chapter I).
In Chapter II, a published article, I present a novel study on aspects of animal personality in the American mink, by revealing, for the first time, consistency in shyness measures across different novelty tests. Interestingly, this study shows that consistency in shyness measures differs across non-social and social contexts, as well as across stages in the approach towards novel objects. This reveals that different aspects of shyness exist in the farmed American mink. These findings highlight the importance of carefully considering the context as well as the limitations of using the shyness-boldness continuum for describing animal personality traits.
Chapter III, a manuscript, adds to the knowledge of animal personality described in Chapter II, by revealing aspects of the shyness-boldness continuum across seasons in the farmed American mink. This study confirms the existence of personality in mink by showing consistency over time for tests in both non-social and social contexts, and it confirms the different shyness-boldness dimensions. Interestingly, a general shift in the positioning of individuals from shy to more bold was evident when comparing the shyness measures in the non-breeding season in December to the early breeding season measures in February.
In Chapter IV, a manuscript in prep, I present a free choice study on female preference for two different males and their signals and cues and the resulting paternity in farmed American mink. The study focuses on three types of signals or cues: olfactory (urine and faeces), stationary-visual (size), and variable-visual (behaviour). We were able to measure a female preference for male stimuli (urine and faeces) in all mink. As expected, this study also reveals that, mate preference and actual choice as shown by paternity are highly complex and rely on multiple cues. The tendencies in this study suggest that we might be able to use olfactory cues to measure female preference for mates prior to introduction, which could improve pair compatibility and breeding success if applied to endangered zoo species.
In the discussion and future perspectives (Chapter V), I summarise the main results of each chapter and suggest directions for future studies. Furthermore, I suggest how this new knowledge on animal personality, mate preference, and mate choice can be used to improve breeding success in managed species.