Cooperative behaviours are found throughout nature, with contributions highly variable between and within individuals. Contributions are affected by fixed and long-term variables such as gender, age and dominance status, as well as shorter term factors such as satiation, danger and audience, which form an individual’s personal context. Sentinel behaviour (where an individual adopts a raised position to scan for danger and warn groupmates of the presence of predators) is a cooperative act which conveys benefits to group members, as well as providing benefits to the sentinels themselves. Here I manipulate satiation state, perceived danger level and the conspecific audience to investigate the relevance of context- dependency in sentinel contributions. In addition to standard measures of sentinel behaviour (time spent as a sentinel, number of bouts, bout duration), I use novel measures of within- bout investment to investigate sentinel contributions through proxies of attentiveness. Experiments show that dwarf mongoose (Helogale parvula) foragers were more likely to become a sentinel when satiated and when under increased danger level, whereas the presence of a neighbouring forager (audience) decreased contributions. Satiation level had the largest impact, with supplementary feeding causing investment in more and longer bouts, whilst changes in average head scanning rate provided evidence for an interaction between the effect of satiation and danger levels. These results demonstrate that sentinel contributions are strongly context-dependent, with effects seen in both overall and within-bout characteristics.
|Date of Award||6 Nov 2018|
- The University of Bristol
|Supervisor||Andrew N Radford (Supervisor)|