Jamie Spence has photographed an adult Mew Gull below the Horseshoe Falls as of 8 am, November 24. I'm not sure of his exact vantage point. A scope is likely necessary. Parking along streets close to the falls is usually limited and/or very expensive. Most birders opt to park at Dufferin Islands and walk down. https://goo.gl/maps/v5rMBqg9zQc8jMRw7 Good Birding, Mike Burrell