Assessing bird shapes in photos

posted by Jerry Liguori at
on Wednesday, June 4, 2014 

Originally potsed @

Something Peter Pyle wrote recently in Birding magazine gave me a good idea for a blog post. Actually, a few posts will follow on the subject, which I think will make neat lessons. Pyle was wondering if this adult male Harrier (image #1) could be sexed as a female based on wing shape [quote: "...could be an anomalous male or perhaps an older female, as also suggested by its broader wings and bulky appearance; females are larger than males in most hawks."]. This particular Harrier is in typical adult male plumage and is a breeding male (as the caption stated) paired with a typical female, so I can't find anything anomalous about this bird, and I can't find a reason to think this male would be a female (maybe the caption should have stated it was the bird on top when they copulated). I don't see this bird as "bulky" either, so I was quite puzzled by that quote alone. "Hawks From Every Angle" focuses on distinguishing the shapes of raptors in flight from all the angles, and "Hawks at a Distance" shows how to identify more distant raptors based on these principles. In these books, it states that male Harriers are shorter-winged and shorter-tailed than females, and hold their wings in a shallower dihedral, but Pyle's suggestion that females having broader-looking wings because they are larger birds is misleading, especially when looking at birds in photos. Be careful: males of several species have broader-looking wings than females, and all raptors appear stockier when seen from a side view (HFEA). Males and females of some species differ in wing beat, juveniles differ slightly from adults in shape on other species, and a so on...but accurately judging any of these differences takes years and years of field experience. For example: I categorized a distant melanistic (an extremely rare type) Harrier in flight in winter 2008 in northern Utah as a male based on shape and flight style (and banded primary tips identified it as a juvenile and not adult male). A melanistic adult male Harrier was found wintering south of Boise, ID four years later, and I believe it was the same bird as the UT bird. So did my experience pay off, or was it a different bird?

It is easy for anyone to make an error judging shape from a single photo. Photos can be deceiving since they are only a split-second snap shot in time. Often, a bird looks stockier, lankier, or more pointed-winged than normal in certain poses, and this is even exaggerated at times in photos. Here is an example: (, and there are other examples of this topic on my blog. A bird such as a Harrier that is known for its narrow wings, can look stocky wing-on or change shape as it changes angles (images #2-7). In fact, the male (image #6) and female (image #7) look as stocky or stockier than almost any raptor in North America from these angles, but that doesn't make them Red-tailed Hawks (as an example) in Harrier plumage. Also, check out this Broad-winged Hawk (image #8), a species known for its stocky appearance that looks quite lanky in this instance. I just posted a quiz bird from CA with a similar theme: ( So, be careful of judging single photos based on shape -- even well known birders such as Peter Pyle have made this mistake. With experience though, it becomes easier.
Anonymous Anonymous said...

Vey enlightening post Jerry, thank you for sharing this insight!

July 20, 2014 at 6:36 AM  

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