Some takeaways from Birkhead on bird senses, for readers interested in these things:
Sight: chickens have no fovea (focal point on the retina) at all while most bird species have one (like us) and some birds e.g. raptors have 2 (p. 17); many birds, probably most, have some degree of UV vision that they use to find food and partners (p. 24). And regarding watching our chickens pecking at things too small for us to see properly, an American kestrel can detect a 2 mm-long insect at 18 m (p. 9).
Sound: hearing in most birds is like our own (p. 71). But the hair cells in their cochleas are replaced on a regular (annual) basis, so they don't lose their hearing with age or through damagingly loud noise as we do (pp. 46-7).
Touch: some birds are indeterminate layers, that is, the number of eggs they lay is regulated through the brood patch; if eggs are removed as they are laid, there is no tactile stimulation of the patch and no message sent to the brain to limit egg laying. Thus a sparrow may lay 50 eggs instead of 5 (p. 93). I guess somewhere along the evolutionary path from jungle fowl to modern chicken that switch got turned off. Also on touch, successful incubation does not demand a constant temperature, but simply one that does not fall too low or get too high, and embryos are far more tolerant of cooling than of overheating (idem). Also on touch, crests or wispy feathers on top of heads probably serve a sensory function like whiskers on cats to help them avoid bumping into things and are associated with species that live in dense vegetation or nest underground (p. 86).