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The long legs and long toes of this backlit bird suggest that we should be looking among the herons and other heron-like birds for a solution. The perch location rules out cranes and the fairly short and stout bill rules out storks, leaving us with the true herons as the remaining members of the potential solution set. The short and stout bill goes a long way toward whittling down our options, as does the fact that the bird is not white. Yes, it’s backlit, but there’s still enough resolution to see that the bird’s plumage is fairly dark. The reductions in solution-set members enabled by bill size and shape and by overall plumage color should leave us with just Green Heron and the two species of night-heron as viable options. Going back to leg length enables us to rule out the short-legged Green Heron.
Since we can see enough vague suggestions of plumage color to know that a) there are no strong dark-light color-tone contrasts anywhere on the bird and b) there is, in fact, fairly heavy streaking on the underparts, we should be looking for features that would enable us to separate juveniles of these two species. Overall plumage pattern in them is quite similar, with details of the size of white spots on the wing coverts and the presence or absence of whitish leading edges of the greater secondary coverts being particularly useful. Unfortunately, such details are difficult to determine in this poorly-lit picture. Oh, we could do it, but those are not the features that I wanted to elucidate this time ‘round.
In flight, the juveniles of Yellow-crowned and Black-crowned night-herons are differentiated by two particular features, but only one of which works in such poor lighting conditions. That feature is the amount of leg that trails behind the tail, with Yellow-crowneds having more than just toes sticking out the back end. Instead, a little bit of the tarsometatarsus (read, the foot bone proximal to the juncture of all the toes; that is, between the toes and the heel) is visible. This difference in foot projection is not created by a longer foot in Yellow-crowned, but by longer bones above the foot. In fact, this difference is created by the considerably longer tibiotarsus of Yellow-crowned Night-Heron relative to the shorter tibiotarsus in Black-crowned Night-Heron -- roughly equivalent to the shin section of our legs; you do know that that big, knobby joint visible in the picture is effectively the bird’s heel, right? This difference creates a different look on perching/standing individuals of the two species, with extensive leg visible between that joint and the body, whereas Black-crowned Night-Heron shows little or no leg between the joint and the body.
Of course, if you grab the picture and lighten it (see below), the bird’s small covert spots and obvious whitish leading edges to the greater secondary coverts are obvious, supporting our identification by leg length.
I took this picture of a juvenile Yellow-crowned Night-Heron at Smith Point, Chambers Co., TX, on 23 August 2013.
The following people (listed by submission date beginning with the earliest) submitted correct answers for the December Bird Photo Quiz—Yellow-crowned Night-Heron:
The following list shows the number of submissions for each species guessed.
The photo and answer for this quiz were supplied by Tony Leukering.