This picture has some blue tones in it because I was shooting with daylight white balance in deep shade. I could have switched to cloudy WB, but that takes time and I didn't want to miss a single moment photographing the leopard in Botswana. I leave my white balance setting on daylight for virtually all of my outdoor shooting, even though I get these kinds of bluish color casts. FIrst, I don't mind this color, but if I did, it's an easy change to make in Adobe Camera Raw or Lightroom by moving the temperature slider. There is enough to think about when shooting fast changing subjects like wildlife, children playing, or sports to deal with the white balance issue.
My settings for this picture were 1/250, f/4, 1000 ISO.