Cackling Goose?!

Last week, an odd looking goose was spotted at Central Park's Reservoir. After much debate, it was concluded that it was probably a Cackling Goose, with the small possibility of it being a hybrid. On Wednesday, I went to search for the bird, starting at the southwest corner of the Reservoir. When I got there, there was a large flock of dozens of Canada Geese there. I looked through them, but couldn't find the goose that looked slightly smaller than the others. Just as I was about to look for the bird elsewhere, I remembered that it was reported in this exact spot that morning. I took one last look, and spotted a goose that looked smaller than the others! It was about 1/3 smaller than the other geese and a bit darker too. Some other birders then arrived and I showed them the goose. They confirmed my suspicions that this is the mystery bird. After much pondering, I have decided that it's decently safe to count the bird as a mostly pure to pure CACKLING GOOSE until further evidence comes to light (UPDATE 2/24: the bird is still shrouded in so much mystery, and chances of it being Cackling are slim, so I am removing it from the list). Yesterday, I failed to find it, but did add a female Red-Breasted Merganser (Year bird #78) to my year list. It seems that the day I will go below one bird per day is fast approaching. At the current total, that day is February 27th, but hopefully I can break it again in April or May.