Any chance there were 39 birds total, i.e., 38 White-faced and 1 Glossy? The reason I ask is that I saw 39 Plegadis sp. overflying Greenlee Preserve late this morning, on a northwest vector that would have taken them straight to Walden.
If it was n=39, I'm adding Glossy to my Greenlee list... ;-)
Ted Floyd
Lafayette, Boulder County, Colorado