Narwhal communication and grouping behaviour: a case study in social cetacean research and monitoring by Marianne Marcoux Department of Natural Resource Sciences McGill University, Montreal February 2011 A thesis submitted to McGill University in partial fulfilment of the requirements of the degree of Doctor of Philosophy © Marianne Marcoux 2011 Table of content Abstract ................................................................................................ iv Résumé .................................................................................................. v List of figures ...................................................................................... vii List of tables ......................................................................................... xi Acknowledgements .............................................................................. xii Contribution of co-authors and remarks on style ................................. xv Original contributions to knowledge ................................................. xvii 1 Introduction ..................................................................................... 1 1.1 Literature review ...................................................................................... 3 1.1.1 The study of social cetaceans ............................................................ 3 1.1.2 Narwhal biology ................................................................................ 5 1.1.3 The changing Arctic ecosystem and its impact on narwhals ............ 9 1.2 Rationale and objectives ......................................................................... 12 1.3 References .............................................................................................. 15 2 Encounter frequencies and grouping patterns of narwhals in Koluktoo Bay, Baffin Island ........................................................... 27 2.1 Abstract .................................................................................................. 28 2.2 Introduction ............................................................................................ 29 2.3 Methods .................................................................................................. 33 2.3.1 Grouping patterns ............................................................................ 34 2.3.2 Environmental correlates of narwhal observations ......................... 36 2.4 Results .................................................................................................... 38 2.4.1 Grouping patterns ............................................................................ 38 2.4.2 Environmental correlates of narwhal observations ......................... 39 2.4.3 Additional marine mammal observations ....................................... 41 2.5 Discussion .............................................................................................. 41 2.5.1 Environmental correlates of narwhal observations ......................... 45 2.6 References .............................................................................................. 57 Linking statement ............................................................................... 66 3 Statistical analysis of animal observations and associated marks distributed in time using Ripley’s functions. ................................. 67 3.1 Introduction ............................................................................................ 67 3.2 Methods .................................................................................................. 71 3.2.1 Ripley’s K and L functions for univariate data ............................... 71 3.2.2 Ripley’s cross K and L functions for bivariate analysis .................. 74 3.2.3 Mark similarity function ................................................................. 78 3.2.4 Example: the narwhal dataset ......................................................... 79 3.3 Results .................................................................................................... 81 ii 3.4 Discussion .............................................................................................. 83 3.5 Appendix ................................................................................................ 95 3.6 References .............................................................................................. 97 Linking statement ..............................................................................102 4 Variability and context-specificity of narwhal (Monodon monoceros) whistles and pulsed calls ...............................................................103 4.1 Abstract ................................................................................................ 103 4.2 Introduction .......................................................................................... 104 4.3 Material and Methods ........................................................................... 106 4.4 Results .................................................................................................. 113 4.5 Discussion ............................................................................................ 115 4.6 References ............................................................................................ 125 Linking statement ..............................................................................130 5 Local passive acoustic monitoring of narwhals in the Canadian Arctic .............................................................................................131 5.1 Abstract ................................................................................................ 131 5.2 Résumé ................................................................................................. 132 5.3 Introduction .......................................................................................... 133 5.4 Methods ................................................................................................ 136 5.4.1 Characteristics of narwhal vocalisation ........................................ 136 5.4.2 Recordings and behavioural observations..................................... 137 5.4.3 Analysis ......................................................................................... 139 5.5 Results .................................................................................................. 142 5.6 Discussion ............................................................................................ 144 5.7 References ............................................................................................ 156 6 Summary and final conclusions ....................................................163 6.1 Social organisation ............................................................................... 163 6.2 Cetacean communication ..................................................................... 164 6.3 Community-based monitoring .............................................................. 164 6.4 Narwhal research .................................................................................. 165 6.5 References ............................................................................................ 166 iii Abstract Narwhals (Monodon monoceros) are gregarious, toothed whales restricted to the Arctic, where habitats are changing and shipping traffic is increasing. Challenges associated with the remoteness of narwhal populations and the general difficulty of studying deep diving mammals have resulted in a lack of knowledge of narwhal social behaviour, which can only be rectified with intensive, direct and systematic observations. I studied the grouping patterns and vocal behaviour of narwhals using non-invasive methods and developed new statistical tools to analyse the data. The field work was conducted at Bruce Head, a peninsula at the mouth of Koluktoo Bay, Nunavut, during the summers of 2006-2008. Shore-based observations were used to delineate narwhal groups by sex and age class. Narwhals travelled in clusters of 1–25 individuals of mixed sex and age class. Narwhals entered the bay in larger groups than they exited. The coloration of narwhal’s backs on photographs was used to estimate their age and investigate their association with individuals of similar age. To analyse these data, I developed statistical methods that examine the distribution of observations in time and their associated characteristics. Using these methods, I found that narwhals form groups with individuals of similar age. The variability and the context of usage of narwhal calls were examined from underwater recordings. Some physical characteristics of narwhal whistles seemed behaviour-specific. Both whistles and pulsed calls might serve in individual- or group-recognition. Finally, given that there is a need for sustained, local monitoring of narwhals, I explored the potential of passive acoustic methods for narwhal monitoring. An automated detector was able to correctly identify narwhal calls in a 25-day continuous recording. There was a correlation between the number of calls manually detected in non-continuous recordings and the number of narwhals observed during the recordings. Non-invasive methods can provide valuable insight into the social organization, communication and movement patterns of large numbers of non-disturbed cetaceans. iv Résumé Le narval (Monodon monoceros) est un cétacé grégaire arctique dont l’habitat