Readers ask about bird droppings, Ice Age cave art and more

Bodily waste is cool, actually

Snot bubbles may help a short-beaked echidna cool off by coating the critter’s nose with moisture, which evaporates and draws heat from a blood-filled sinus, helping to cool the blood, Elise Cutts reported in “Adorable spike-balls beat the heat with snot bubbles” (SN: 2/11/23, p. 32).

Other animals also have creative ways of using fluids to stay cool. Some birds, for example, urinate on themselves to survive hot days, Cutts wrote. Reader James Wilson noted that the word “urinate” might be misleading, since bird waste is typically a mix of urine and feces.