The importance of delineating networks by activity type in bottlenose dolphins ( Tursiops truncatus ) in Cedar Key, Florida

Abstract

Network analysis has proved to be a valuable tool for studying the behavioural patterns of complex social animals. Often such studies either do not distinguish between different behavioural states of the organisms or simply focus attention on a single behavioural state to the exclusion of all others. In either of these approaches it is impossible to ascertain how the behavioural patterns of individuals depend on the type of activity they are engaged in. Here we report on a network-based analysis of the behavioural associations in a population of bottlenose dolphins (Tursiops truncatus) in Cedar Key, Florida. We consider three distinct behavioural states—socializing, travelling and foraging—and analyse the association networks corresponding to each activity. Moreover, in constructing the different activity networks we do not simply record a spatial association between two individuals as being either present or absent, but rather quantify the degree of any association, thus allowing us to construct weighted networks describing each activity. The results of these weighted activity networks indicate that networks can reveal detailed patterns of bottlenose dolphins at the population level; dolphins socialize in large groups with preferential associations; travel in small groups with preferential associates; and spread out to forage in very small, weakly connected groups. There is some overlap in the socialize and travel networks but little overlap between the forage and other networks. This indicates that the social bonds maintained in other activities are less important as they forage on dispersed, solitary prey. The overall network, not sorted by activity, does not accurately represent any of these patterns.

Bottlenose dolphin (Tursiops truncatus) social structure in the Shannon Estuary, Ireland, is distinguished by age‐ and area‐related associations

“…), Cedar Key (0.03 ± 0.08; Gazda et al . ), St Johns River, Florida (0.05 ± 0.02; Ermak ), Sicily, Italy (0.06 ± 0.02; Papale et al . ), and the Sado Estuary, Portugal (0.45 ± 0.15; Augusto et al .…”

“…() to determine whether behaviorally specific preferred associations existed within the population, as it is important to assess the effect of activity state on associations in fission‐fusion networks (Gazda et al . , Moreno and Acevedo‐Gutiérrez ). Restrictions were implemented in SOCPROG for each of four main activity states: rest, travel, social, and forage.…”

Infected or informed? Social structure and the simultaneous transmission of information and infectious disease

“…Theoretical models using multilayer networks have been valuable in understanding the spread of a single parasite species or piece of information through multiple types of interaction, and the consequences of multiple spreading processes occurring across the same set of individuals (for example, multiple information types: Liu et al , multiple parasites: Azimi‐Tafreshi or infection and information together: Funk et al , Funk and Jansen , Marceau et al , Granell et al , , Zhao et al , Guo et al ). Applying these approaches to animal behaviour research (Silk et al , Finn et al ) requires data on multiple types of social connections simultaneously (Franz et al , Gazda et al ), and quantification of the importance of these different social connections for transmission (Aplin et al 2015).…”

Simple foraging rules in competitive environments can generate socially structured populations

“…Our model highlights that initial dietary specializations could have been driven by competition and not necessarily only by innovation. There is growing empirical evidence that food availability and clumpiness can drive flexibility in social and foraging ties of marine predators (e.g., Gazda, Iyer, Killingback, Connor, & Brault, ), even in the stable social tiers of killer whales. Type, biomass, predictability, and density of prey influence not only foraging strategies but also social strength and connectivity, suggesting that ecological conditions can bend even phylogenetic inertia (Beck et al., ; Foster et al., ; Tavares, Samarra, & Miller, ).…”