Attendance patterns of provisioned Australian humpback dolphins (Sousa sahulensis) in Tin Can Bay, Australia – Further indication of male bonding and alliance

Abstract

Tin Can Bay, Queensland, is one of four free-ranging dolphin feed provisioning sites in Australia and the only one featuring Australian humpback dolphins (Sousa sahulensis). The site attracts the same 5–10 dolphins a year, most of which return regularly, and some which have been in attendance since the 1990s. Historical records were obtained for the period March 2010 to March 2021 covering dolphin attendance to the provisioning station including dolphin name, arrival time, and departure time. Tourist numbers were also obtained which included the total number and how many of that total directly took part in provisioning. Attendance of dolphins to the provisioning site has increased over the years both in frequency and total numbers. There was evidence of group cohesion between four particular dolphins (one mother-offspring pair and one male pair). The strongest pairing was seen between two males, indicating bond formation in adult male humpback dolphins, which may be indicative of an alliance. Specific events were also looked at in detail including cyclones, flooding COVID-19 restrictions, which reduced dolphin and/or human attendance.