Genetic and experiential manipulation of fear-related behavior in Japanese quail chicks (Coturnix coturnix japonica).

We examined effects of environmental enrichment and regular handling on fear-related responses in chicks of Japanese quail (Coturnix coturnix japonica) selected over several generations for short or long tonic immobility (STI and LTI, respectively). STI chicks froze less, vocalized and walked sooner and more in an open field, emerged sooner from a hole-in-the-wall box, and showed shorter TI reactions than did chicks of the LTI line. Similarly, environmental enrichment reduced silence and inactivity in the open field, accelerated emergence, and attenuated TI. Regular handling promoted open-field vocalization and reduced the duration of TI but exerted no other significant effects. Principal component analysis showed that the responses in the 3 tests were not independent, which implies that they measured the same underlying factor. The genetic and experiential manipulation of stimulus-specific fears and of general fearfulness is discussed.