Yesterday I commented on the white splotches I was seeing on crows lately. I said it looked like someone had thrown paint or whitewash on them. Looking at some photos of crows gathering in trees around the Arboretum and farm last night, I discussed this issue with someone else who said what I had been thinking: the whitewash could well be excrement. Think of it. All these birds roosting in trees, doing what birds do after eating, and dropping the stuff on the poor crows beneath them. I wrote to Michel Gosselin at the Canadian Museum of Nature about this, and he confirmed that was what it was. I don't recall seeing this the rest of the year, and it stands to reason that once crows disperse in breeding season, they wouldn't be congregating in such huge numbers, so no problem with bombs from above :-) Michel also confirmed that the white wing patches I've seen and photographed on some crows around the farm is a lack of pigmentation in the feathers.