I need to know every information available that talks about the heron's eyes?

Answer 1

The majority of heron species (Aves, Ardeidae) forage on aquatic prey in shallow water. Prey detection, aiming and the beginning of the capture strikes are performed while the heron's eyes are above water. For most angles, as a result of air/water light refraction, the apparent image available to a heron is vertically displaced from the prey's real position. Herons must therefore correct for refraction. The ability of hand-reared herons of four species to capture stationary prey (fish) underwater (submerged) or in air (aerial ) was tested. Three species (little egret, Egrett garzetta, squacco heron, Ardeola talloides, and night heron, Nycticorax nycticorax) normally forage in aquatic habitats while the fourth (cattle egret, Bubulcus ibis) forages in terrestrial habitats. No individuals missed aerial prey. Success rates of little egrets and of squacco herons with submerged prey were high, while night herons became less successful wit h increased prey depth and/or distance. In cattle egrets, success rate was low and negatively correlated with prey depth, The observed interspecific differences may thus be related to (1) differential ability to correct for air/water light refraction and (2) the species' foraging behaviour. We suggest that cattle egrets are in the process of losing their ability to cope with submerged prey.