I started birding in Ecuador five years ago. I didn't have good field guides, good bins nor much experience but I still became better with everyday and am pretty certain, that my fault rate in the end was below 5-10%. I might not have spotted the rarer species, but I found a fair lot of common and uncommon species, in the end 480 species.
One day I was birding around Coca in the eastern lowlands and in some wetlands flushed a big flock of big birds, including Black and Turkey Vultures, Snowy, Great Egrets and Little Blue Herons, Anhinga, Wattled Jacana and Southern Lapwing. But there was one more bird, a big grey heron. I knew there were only two such species in ecuador: Cocoi and Great Blue Heron. Having just seen several GBHs in Galapagos I didn't see anything that didn't match, but after a little research back home I noticed this would have been an extremely rare sighting.
3 days later I returned to the same spot, this time more cautious in hope not to flush the birds. And indeed all those Vultures, Lapwings, etc. didn't fly away. Only one bird flushed: The big grey heron. Again I only had brief views, but this time I focused on the head pattern and it was certainly not that of a Cocoi, but that of a Great Blue Heron. But before I could see any more features it had already disappeared. This would have constituted the first or second record of Great Blue Heron in the amazonian lowlands of Ecuador.
However I'm not sure if maybe young Cocois might look just like Great Blues and what features would have been the distinguishing ones, since I can't really find any reliable pictures of these on the internet.
In the end I ended submitting this bird as Cocoi that looks like Great Blue Heron. Ironically two years later just 2km away a GBH was found and photographed
Maffong