Excerpts from Jim Conrad's
from the January 26, 2007 Newsletter issued from Sierra Gorda Biosphere Reserve, QUERÉTARO, MÉXICO
SNOWY EGRET & NEOTROPIC CORMORANTS
For the last few weeks I've been seeing at least one Snowy Egret doing something I didn't know an egret could do. When he spots a school of fish near the reservoir's surface he flies into the school's center, lands in the water and while floating like a duck stabs with his long beak all around him. Often I see this bird come up with silvery fish in his beak, so the behavior seems to be working.
Snowy Egrets and all other egrets and herons are "supposed" to wade with their long legs in shallow water and spend lots of time standing frozen in place until a fish swims by, which the bird then snatches with his pointed beak, right? I told my ornotholigist friend Jarvis in North Carolina about this and he responded that "David Sibley wrote that researchers have described more than 30 types of foraging behavior in herons and egrets." Therefore, it's dangerous to stereotype an egret.
The story doesn't stop here. A small flock of Neotropic Cormorants always is fishing nearby and when they see the Snowy Egret plop onto the water's surface anywhere in the lake they all rush to participate in the fishing, knowing that the egret wouldn't have landed on the water if there'd been no school of fish there. The cormorants splash into the water and dive with such fervor, churning up the water something awful, that the heron usually looks a bit confused, then flies away.
However, the strategy works both ways. Sometimes the heron sees that the cormorants have located a school and are feeding nicely, so then the heron flies out into the lake and lands amidst the diving cormorants, who don't seem to notice or care about their visitor's arrival.
This isn't the only curious behavior I've seen lately on behalf of a long-legged shore-wader. The other day I saw three White-faced Ibises on a wooden fence next to a cow pen, along with about a dozen Cattle Egrets, scavenging whatever they could from the black mire the cattle stood in. Seeing Cattle Egrets do this didn't surprise me but who'd expect a nice White-faced Ibis to scavenge in a cow pen? They're supposed to be in "brackish and freshwater marshes," as the books say.
I'm glad these birds are showing such flexibility of behavior. That just may be what eventually saves them from extinction.