Hi Martin & others interested:
The Snow Goose that Tom is referring to at Van Cortlandt Park, looks like this.
It has been there since 2016.
https://1.bp.blogspot.com/-yTlslLuX218/WGPR-MT39vI/HQA/12gH5395W4oqVwAILCgMqDeSsK5JwAstgCLcB/s1600/smSNGO-5661.jpg
A Ross's looks like this one,
Dear Martin & all,
The 'white goose' with the Canada Goose flocks that gather & feed on
the Parade Ground of Van Cortlandt Park (Bronx County, NY) is a Snow
Goose; simply by size relative to the many Canadas it is with, we can
be rather certain of that. Details observed with closer scopin