Fig. 3From: Spatial variation in avian bill size is associated with humidity in summer among Australian passerinesThe interaction between humidity and maximum temperature influencing bill surface area for 36 species passerine from the Meliphagoidea (n = 2867 individuals). Humidity is mean summer water vapour pressure (hPa) and temperature is mean maximum summer temperature averaged for the preceding 5 summers prior to capture; summer is defined as the months December to February. Colours represent categories of bill surface areaBack to article page