The blue jay measures 22–30 cm (9–12 inches) from bill to tail and weighs 70–100 grams (2.47–3.53 oz), with a wingspan of 34–43 cm (13–17 inches). There is a crown of feathers on the top of the head, which may be raised or lowered according to the bird's mood. When excited or aggressive, the crest may be fully raised. When scared, the crest comes outwards, brushlike. When the bird is feeding among other jays or resting, the crest is flattened to the head.