Terns, gull-like birds, patrol Lake Puckaway, gliding gracefully above the water, watching for fish below. If you haven't stopped to watch their aerobatics while on the lake, you should. Wisconsin is home to four species of tern: Forster's Terns, Common Terns, Black terns, and Caspian Terns.
Black Terns are the most different of the group. Breeding black terns are slate gray to black in color; while the other species play on a white and black theme. Caspian terns are the next easiest to pick out of the group, simply based on size. They are much larger than the other terns. The other terns are larger than swallows but smaller than most gulls, while the Caspian Tern is a good-sized bird sporting a wingspan over 4 feet.
The Common Tern and Forster's Tern are most similar in color and size. I find them tricky to distinguish. Tips I've picked up while birding that seem to help include: 1) Look for the primary feathers on the edge of wings when resting, if dark, it's more likely a Common Tern. The Common Tern's beak and feet tend to be a deeper red-orange in color, where as the Forster's Tern is a lighter orange. Forster's are also supposed to have longer legs than a Common Tern. The challenge with using most of these tips, is that they are comparisons between the two species so without them side-by-side they can be tough to distinguish. That leaves us with habitat as a characteristic. Generally Forster's Tern is more associated with freshwater marshes and shallow lakes, while the Common Tern prefers more open waters. Both species are present on Puckaway.
You can spot terns all around the lake, but hotspots include: the tern rafts near the dredge bank (of course), Haystack Point and near the Dead River on the west end, and patrolling around the milfoil mat growing in the western side of the lake. We seem the regularly enough on the North Shore that my children no longer find them exciting.
I'm reasonably confident that I have spotted all four species of tern on Puckaway. The lake has plenty of small fish for them to catch when they dive head first into the lake with a loud plop! Floating vegetation, piers, the dredge bank, and the tern rafts give them many places to rest. And the rafts support a breeding colony of Common Terns.
Likely Forster's Tern nest on vegetation mat near the dredge bank.
The red-orange beak and feet make me lean Common Tern, the floating vegetation - Forster's.
Black Tern fishing near Haystack Point.
Large Caspian Tern (also note the black feet) swoops between Pelicans.
No comments:
Post a Comment