Meeting Abstract
Bottlenose dolphins live in fission-fusion societies where female and male bonds are shaped by different ecological pressures. Across most study sites females form moderate within-sex bonds, while male bonds are highly variable; males range from primarily solitary to strongly bonded within first-order alliances, which cooperatively herd females. Also, multi-level alliances have been documented in one site (Shark Bay, Australia). Here, we use two years (2011-2013) of photo-identification data from the St. Johns River (SJR), Jacksonville, Florida to examine within and between sex bonds. Coefficients of association (half-weight index, HWI), a test for preferred/avoided associations, and a Mantel test were calculated within SOCPROG 2.5. Analyses were limited to females (FEM, n=37) and unknown sex individuals (UNK, n=80, including 10 known males), with 10+ sightings. UNKs were further divided into allied (HWI≥0.8) and unallied (HWI<0.8). The community interacted non-randomly (p<0.01) with 172 preferred associations, largely between UNK-UNK dyads. Within-sex bonds were significantly stronger than between-sex bonds (Mantel test, p=1); FEM-FEM top associations averaged 0.3±0.1 and UNK-UNK top associations averaged 0.6±0.3. Twenty-six UNKs met the criteria for alliance status (11 dyads and one quad). Twelve of these individuals had HWI≥0.3 with other alliances, indicative of 2nd order alliances. This is the first report of 2nd order alliances in bottlenose dolphins outside of Shark Bay, suggesting similar ecological pressures shaped male mating strategies in the SJR. Continued research regarding regional differences in social complexity will facilitate comparison and clarify the variables governing alliance formation.
