Common vs Forster's Terns

A Common Tern gives itself a shakedown. Note the partial black "hood" extending all the way around the back of its neck, and bold carpal bar. Ormond Beach, Port Hueneme, CA.

Birders struggle with tern identification...it is a source of Fear and Loathing for beginner and veteran alike. Royal vs. Elegant, Black vs. White-winged, Sooty vs. Bridled, Common vs. Arctic, Common vs. Roseate, and perhaps most frequently of all, Common vs. Forster's. Here are a few shots and notes that could be helpful to tell immature birds of these two species apart. The process is frequently messy and not always a perfect match for field guides (which is their fault, not yours), but it can be done! As always, knowing status and distribution can provide some great hints, but anything can happen during migration.

Forster's Tern, with "earmuffs" that don't wrap around the back of the head. Common Terns never sport this kind of headgear. Poe Road, Salton Sea, CA.

A Common Tern conveniently shows off its outer tail feathers, which feature black on the outer webs. Ormond Beach.

A Forster's Tern stoops to catch a Tilapia. Check out the white/gray tail. This bird has extensive black in the primaries, which birders often assume is associated only with Common Tern. Poe Road.

One of my better Common Tern shots. Note how pale the primaries appear from this angle, which is not what birders expect...but everything else points exactly to Common, including the delicate bill. Taking tern pictures can be extremely frustrating, but when they suddenly bank to dive on a fish or other prey, it makes for a pretty sweet shot if you can catch it in time. Ormond Beach.

This is a pretty good quiz bird. There is black in the tail, but the outer retrices are clearly edged in white...this is a Forster's Tern. Poe Road.

Here's a pretty "typical" Forster's Tern, with earmuffs and pale upperwing. Also note the slightly longer and heavier bill. Poe Road.

Common Tern. Compare the underwing pattern of this bird with the above Forster's. Ormond Beach.

This Common Tern has a touch of yellow at the tip of the bill. Although not a frequently observed trait, it happens enough for a birder to think twice before you think you find an out of range or hybrid Sandwich Tern. Poe Road.