With apologies to Raffi’s lyrics for Down by the Bay
“Down by the swamp, where the water lilies bloom
I take my camera and my big zoom.
I edge up close, the birds won’t stay —
Did you ever see a duck, stand in the muck?
Did you ever see a heron that didn’t like sharin’?
Did you ever see a bird that didn’t say a word?
Did you ever see a Snapper looking so dapper?
Down by the swamp.”
I don’t know what these egrets were catching, but they caught a lot of them. According to a study done by H. Mincey in Georgia, Great Egrets catch something with 70% of their strikes, which makes this wait and strike strategy highly efficient. However, I was surprised to learn that the average size of prey taken by these birds was only 4-6 cm (1.5-2.5 in). They must have to consume a huge number of such small items to meet their daily energy needs.
Like some other avian species, herons and egrets gather split visual field information from each eye. The upper part of the field provides a lateral monocular view of the landscape around the bird (useful for scanning for prey as well as other encroaching herons — or photographers), and the lower part of the visual field provides a binocular field of view of what is directly beneath the bird. It’s like having four eyes instead of two! In tilting its head and neck to the side, the bird is probably using monocular vision to fix the position of the prey in the water while reducing glare from the angle of the sun on the water.