Fig. 3
From: The bare head of the Northern bald ibis (Geronticus eremita) fulfills a thermoregulatory function
Variation in the difference between Tsurf and Ta of Northern bald ibises. Data are shown in 0.5 °C intervals along Ta values ranging from 21.0 to 42.5 °C in the head (a), the bill (b) and the black feathered body (c). Symbols represent mean ± s.e. Red symbols include measurements taken on birds in the shade and directly exposed to sun light, while blue symbols only include measurements on birds in the shade. Symbols without bars indicate that only one measurement could be obtained for that specific Ta. Horizontal black bars above graphs represent the range in Ta for which the mean Tsurf - Ta values are significantly different from the mean Tsurf - Ta in the window of 37–42 °C Ta