Despite now having lived here for 4+ years, I still struggle with identifying the differences between these two swan species at times. Hearing them call is the best way to separate them for me but they are not always talking… Birders know that seeing two similar species side by side is a great way to differentiate but many times swans are distant and in large groups. Last weekend, we were able to see a single Trumpeter and a single Tundra side by side and in good light. When side by side, it is easy to see the overall size difference and different bill size and structure.
The Trumpeter on the left looks so much more robust even without looking at other field marks such as the yellow on the lores of the Tundra. Not as easy to notice if they aren’t side by side for comparison. Tundra Swans are said to have more distinct looking eyes as the black from the bills of Trumpeter’s is much more connected to their eyes. This is true in this photo. The Tundra’s eye looks much more separate from its bill.I’ve heard that another somewhat reliable difference is that, if they are looking straight at you, Trumpeters tend to have more of a “V” shape where their bills meet their foreheads (between the eyes) compared to Tundra. This is certainly true on this photo but I’ve heard it isn’t always reliable.It is also true in this photo I took in early March last winter showing two Trumpeters in the front and a Tundra in the back. Notice the clear “V” at the top of the middle Swan’s bill and the straight line on the back Tundra.Another comparison shot from last March. This angle really shows the more distinct eye of the Tundra.
Through looking closely at these pictures and writing out some thoughts, I think I’m going to start looking more at the distinct eye field mark. Looking through pictures, this appears to be quite reliable. I guess another option is to insist they speak or line up side by side.
revealednature.com 