The immature Ring-billed Gull and immature Herring Gull look very similar. We were able to I.D. this as a Ring-billed Gull as follows:
- The gull was by itself, but very close to a flock of Ring-billed Gulls. There were no adult Herring Gulls nearby as far as we could see.
- The bill looks more like a Ring-billed Gull's bill; it is not as bulky as a Herring Gull's bill.