September/October 2018: Similar Species
Many bird species have very similar counterparts, and birders must use subtle differences in plumage, proportions, and bill shape to identify them. In some of these cases, like with Carolina and Black-capped Chickadees, birders can almost always use range to identify the species. Although this is a useful shortcut, there are some regions where overlap occurs and we must pay close attention in order to identify the bird. Of course, some similar species have lots of range overlap, and that makes them even trickier! Hopefully this quiz will help you learn a few of these acute ID points, if you don’t already know them.

Bird 1: Let’s start with a question that has long troubled many birders. This shorebird is obviously a dowitcher, but which one? Here’s a hint: an excellent field mark in both basic and alternate plumage has to do with the patterning of the underwing (*cough* the amount of white *cough* *cough*). Look at the lesser coverts in the “armpit” area at the base of the wing. This field mark is even more important in basic plumage, when dowitchers are even harder to identify.

Bird 2: Among other features, the yellow on the crown of this adult male woodpecker tells us that it is either a Black-backed Woodpecker or an American Three-toed Woodpecker. Although these two species may look similar at first, there is one obvious difference. When I took this photo, I knew that only one species was likely in the area but this is not always reliable. There are many places where both species can be seen simultaneously, so it’s best to know the difference.

Bird 3: Lesser Scaup, Greater Scaup, or Ring-necked Duck? These waterfowl look alike, but if you know the differences they won’t be a problem. On this bird we can pretty easily rule out Ring-necked Duck. That species would have a white eyering, uniformly grayish cheeks (rather than the isolated white oval and brown cheeks we see on this bird), less white at the base of the bill, and slightly different bill and head shape. Now for the more difficult question: Which scaup is this? Look at the head shape and bill shape to find out. The amount of creamy-white at the base of the bill can also be a clue, but the previous features are more reliable.

Bird 4: It is easy to tell this is a cormorant, but identifying it to the species level may be trickier. The bill may be the best feature to look at, but head shape, structure, and plumage may also help you.

Bird 5: Although some species of grouse are distinctive, many can be difficult to tell apart. This species can nearly always be identified by range, except for in a very small area of overlap. The air sacs on males are very different colors, but they are not always visible. When I photographed this bird I was not in an overlap area and I saw the air sacs, so the identification was easy. But what if I was in an overlap location and I didn’t see the sacs? Here’s a hint: a birder would have to look at the amount of white on the sides and flanks to identify this grouse.

Bird 6: Here we have an adult female ptarmigan. If I revealed the location its identity would be obvious, but there are areas where one cannot rely on location alone. We'll want to look at the overall plumage tone, but there may be another very important field mark to look for.

Bird 7: Black and Pigeon Guillemots are very similar, but have one easy field mark. Usually it’s safe to say that guillemots on the west coast are Pigeon Guillemots, while ones on the east coast are Black Guillemots. However, both species are possible (Pigeon Guillemot is more common) in Alaska. As with many birds in this quiz, the identification of this bird relies on the amount of white we see in the plumage.

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