Situational factors that influence the level of fear of human by laying hens (1993)

Hemsworth, P. H., Barnett, J. L., Jones, R. B.

Abstract

On the basis of the withdrawal responses of birds to an approaching experimenter, fear of humans may decline from moderate levels among birds housed in Tier 1 (bottom) to Tier 3, in both systems and then sharply increase from Tier 3 to Tier 4, in the four-tier system, reaching the highest level recorded.