Figure 1.
The proportion of time spent shoaling with the body size matched shoal.
Solid lines and filled circles represent large test fish, dashed lines and open circles are small test fish. The dotted line at 0.5 represents no preference. Error bars represent ± 1 S.E. There is a significant effect of body size (p<0.001), as large fish show a stronger preference than small fish, and a marginal effect of predation risk (p = 0.059).
Table 1.
Results of the generalized linear modelling analyses of the effects of predation risk, body size and unmatched shoal size on both response variables.
Figure 2.
The number of times the test fish crossed the zone lines (switched shoals).
Solid lines and filled circles represent large test fish, dashed lines and open circles are small test fish. Error bars represent ± 1S.E. There is a significant effect of predation risk (p = 0.004) and body size (p<0.001), but no interaction. Small fish swap shoal more often than large fish overall.
Table 2.
Study sites (rivers), their geographical location, the predator species observed approaching the confined stimulus female, the mean number of predator approaches to the container (mean abundance) of the predator across 5 pools, and the predation risk rank assigned to the river with 1 as the highest risk.
Table 3.
Summary of experimental treatments.