May 18, 2008
Seeing the light
There's been a lot of back and forth discussion about the subspecific ID of ORANGE-CROWNED WARBLERS this season. The three recognized forms differ in the amount and position of grays, greens and yellows in their plumage. The patient observer can, with practice, pick out the obvious individuals. But the careful observer will also begin to notice that light plays an important role in how we perceive these difference.
Below are photos of the same female lutescens Orange-crowned. The first was taken in bright sun, the second in the deep shade of a Sitka Spruce. Note how much grayer the bird looks out of the direct sunlight. The wing covert are most obviously different looking, but the eye-ring also appears whiter in the shade.
The second photo set is of just the wing of this same bird. Most striking here is the difference in inner and out webs of the flight feathers and the feather shafts. Also notice that the buffy tips of the greater coverts (which suggest this is a second year bird) all but disappear in the bright sun photo.
The point here is that there are advantages and disadvantages to seeing a bird in bright sunlight and part of the process of seeing the whole bird is seeing it in the right light.
Posted by mbalame at May 18, 2008 4:42 PM