Animal personality (i.e., consistent individual behaviour over time/across contexts) is made up of distinct trait continuums (e.g., docile-aggressive; docility) that can play an important role in shaping the behavioural responses of animals, and therefore, can influence fitness. Understanding personality in animal populations can be a useful tool to aid conservation decisions. To date, limited research on personality has been carried out in seabirds, especially species from the family Alcidae. This family, which includes the razorbill (Alca torda), is characterised by a stout body which facilitates diving but results in high energetic costs of flight. In comparison to personality, individual consistency in seabird behaviour (e.g., migratory route) is well studied, but studies rarely compare across species. If individuals within a population behave consistently (e.g., migratory site fidelity), but differences are present among individuals (i.e., behavioural diversity), this variation may expose components of populations to varying threats (e.g., offshore wind development). Therefore, understanding this behavioural variation across and within species will aid in the protection of populations with lower diversity, which are more likely to experience population declines. The aims of this thesis were to:

1. Determine the best method for quantifying the docile-aggressive trait in razorbills (Ch.1).
2. Investigate relationships between docility and razorbill behaviour during the breeding (Ch.2) and non-breeding (Ch.3) periods.
3. Explore behavioural diversity in migratory routes of seabird species that breed in Atlantic Canada (Ch.4). In Chapter 1, I found that different behavioural tests had varying suitability for identifying docility in razorbills. Of the tests, standardized observer ratings were the best test for quantifying docility in razorbills and potentially other hard to observe species. In Chapter 2, I found that razorbills exhibit consistent behaviour during the breeding period, but this consistency is context dependent (i.e., varying prey availability periods) and not related to docility. Additionally, I found no relationship between fledging success and docility. In Chapter 3, I found individual consistency in razorbill non-breeding behaviours but no relationships between any observed non-breeding behaviours and docility. Finally, in Chapter 4, I found varying levels of behavioural diversity both within and across seabird families (Alcidae, Laridae and Sulidae).