Harth M S, Heaton M B
Science. 1973 May 18;180(4087):753-5. doi: 10.1126/science.180.4087.753.
Overt behavioral arousal was elicited by light stimulation in pigeon hatchlings. The sensitivity is not mediated via the retina or by direct stimulation of the brain, but rather it is most likely a dermal sensitivity.