Animals exhibit a wide variety of social behaviours that are shaped by the external group social structure. Thus, understanding social behaviours and processes requires examining the individual social associations that form the basis of a group’s social network. The first objective of this thesis was to assess the consistency of social position within wild networks of black-capped chickadees (Poecile atricapillus) and to evaluate the effects of individual behavioural traits (exploratory personality and social dominance) on network position. Intra-annual social position was found to be repeatable and centrality increased with dominance rank, suggesting that dominant individuals occupy more central positions. The second objective of this thesis was to evaluate how network position and individual traits influence the transmission of social information through groups; the use of information acquired by other group members is expected to be an important benefit to group living. Social information regarding the location of novel foraging patches was observed to be transmitted through all eight chickadee groups. The rate of information transmission was found to be positively associated with dominance rank, but was not influenced by exploratory personality, indicating that dominant individuals may have greater access to social information than more subordinate individuals. The final aim of this thesis was to assess if social information transmission varied between urban and rural environments, as increased resource variability in more rural sites was expected to lead to higher reliance on social foraging cues. However, no effect of level of urbanisation was detected on the transmission of social information regarding novel food sources, which may indicate a habitat-independent strategy of social information use in chickadees. In general the results from this thesis indicate the importance of dominance status on individuals’ position within a social group, which can lead to differential exposure to social processes, such as social information transmission.

I characterized dusky dolphin (Lagenorhynchus obscurus) underwater bait-balling behaviors and acoustic signals, and compared data between Argentina and New Zealand (NZ) to investigate the roles of ecology versus social learning. I quantified prey herding and capturing behaviors from video footage, and I analyzed acoustic signals from narrowband recordings. In both locations, I related bait-balling behaviors and acoustic signals to group and prey ball sizes. In NZ, I also related dolphin behaviors to prey ball escape behaviors and acoustic signal parameters to examine proximate functions. Observed herding behaviors typically involved dolphins swimming around or under a prey ball using a side body orientation, while dolphins typically captured fish from the side of a prey ball using a ventral orientation. Coordinated prey-capture behaviors may have made it easier for dolphins to capture fish by trapping fish between dolphins. Signals were categorized as click trains, burst pulses, and combinations due to a bimodal inter-click interval distribution. I observed 3 whistle-like chirp-screams, but no whistles. Sequences of burst pulses also occurred that contained 2-14 burst pulses that aurally and visually appeared closely matched. Similarities between locations suggest that ecological context related to broad behavioral and acoustic parameters, while social learning differences may occur on a finer scale. In NZ, prey balls exhibited horizontal and vertical movements, but the only behavior that preceded escape was “funneling”, the brief formation of a ball shape where the height was at least twice the width. Dolphin behaviors that related to prey balls ascending were type of herding pass, location of prey-capture attempts, and body orientation during attempts. These behavioral parameters may also be used to counter vertical prey escape behaviors. In NZ, all signal categories had a direct or indirect role in capturing prey. Click train-burst pulses were likely used for echolocating on prey, burst pulses and sequences appeared to have communication roles, and the role of click trains was ambiguous. No signal categories appeared to have a herding function, but the sheer number of signals emitted may have caused fish to cluster together more tightly and therefore facilitated capture.

<p>Diss. (sammanfattning) Umeå : Umeå universitet, 1995, härtill 6 uppsatser.</p> / digitalisering@umu