How Group Size Affects Vigilance Behaviour in Feral Rock Pigeons

How group size affects vigilance behaviour in feral Rock Pigeons/Doves (Columba livia) within urban street and urban park environments.

To enhance their chances of survival any prey species adopts varying methods of defence from predators, high amongst these strategies is for prey species that move in herds or flocks, is group vigilance. According to Ives and Dobson (1987) the detection affect renders a predator more likely to be detected by a larger group and the dilution affect increases the individual survival rate of any singular member of the group as the group size increases this was further supported by Dehn (1990). This experiment aims to ascertain whether, and if so how, increasing group size affects the vigilance behaviour of Rock pigeons (C.livia).
The vigilance of the target C.livia, was measured by selecting an individual, through a process of random number generation, from within a group, for the purposes of this experiment a group was any pigeons within 5-6 meters of each other and group size was rated from 1 individual to 10+. The selected pigeon was identified as being vigilant when the top of their head was raised above the level of their back, to reduce confusion should a pigeon bob up and down too rapidly to stop and start the stopwatch the entire action would be timed and recorded as one bout of vigilance. The data collected comprised of, groups size (1-10+), whether food was present at the site, the duration of each bout of vigilant behaviour and the total frequency of vigilant outs within a timed 3 minute period of continuous sampling. This was completed in both an urban park and street environment and a total of 259 subjects were observed.
Once the raw data had been collected the mean duration and frequency per minute was calculated. The results were then tested for normality using Shapiro-Wilk and Kolmogorov tests to determine whether further analysis of the data should be parametric or non-parametrically...