As originally formulated, the selfish-herd theory of prey species aggregation assumed that predatory attacks were...

As originally formulated, the selfish-herd theory of prey species aggregation assumed that predatory attacks were equally likely to be launched from any position within the environment. In some circumstances (e.g.. avian predators attacking prey from above), such an approach is appropriate. However, as James et at. argue, in many predator-prey associations, attacks are unlikely to occur from positions within the group. For example, it is likely that an ambushing predator waiting in the path of a group would be detected before the group moves over its position. Hence, in many ecological situations, predatory attacks on grouped prey will occur exclusively from outside the group. In such circumstances, there is a strong premium to a group member in being in the interior of the group.

The passage suggests that compared to members of the prey groups in "some circumstances." certain members of the prey groups in "many ecological situations" are likely to be less