Answer to Pop BirdQuiz 10: New Jersey, June

 

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Here we have two brightly patterned shorebirds in their spring finery. Let’s start with two points. First, in fall when most shorebirds typically sport drab combinations of gray and brown, we need to rely heavily upon their structural characteristics: size, shape, and leg and bill length. In spring their bright plumage makes it much easier to identify them, but as we soon will see, structure is still helpful. Second, with shorebirds it is very helpful when they are in mixed flocks, because if we can identify one bird unambiguously, then we are in a better position to identify the others based on their relative sizes.

Let’s begin with the bird on the right. It has a very striking pattern, with a dramatic black-and white facial and neck pattern unlike that of any other shorebird, a relatively short pointed bill, and bright orange legs. This combination unmistakeably points towards a Ruddy Turnstone. The most notable plumage characteristics of the bird on the left being its bright orange breast with the orange continuing into parts of its face, and those odd feathers protruding from the back of its neck. When we see that kind of odd neck plumage, we should be thinking immediately of a Ruff, which is a rare but annual visitor in New Jersey. Ruffs are also a bit larger than Ruddy Turnstones and have a great deal of orange plumage in spring, consistent with this identification. Yet some things are inconsistent: this bird has a slightly drooping bill, while the bill of a Ruff is straight, and this bird has black legs, while Ruffs have yellow legs. So what other birds have this much orange plumage?  Curlew Sandpiper also is bright orange, but has a more sharply downcurved bill, and would be smaller than a Ruddy Turnstone (I told you that the structure/size comparison would be important!). The remaining candidate is Red Knot, which has bright orange undersides and facial pattern, a slightly droopy bill, black legs, and is a few inches larger than a Ruddy Turnstone. So all looks good. But what is that odd neck plumage? Its certainly not normal on a Red Knot, so it is presumably just an aberrant set of feathers in this individual. Interesting, no? We’ll chalk it up to interesting individual variability.  A more typical Red Knot is shown below for comparison, although in slightly less mature plumage.
Red knot

 Posted by at 8:24 PM