Birds do the strangest things--like monitoring the temperature of a brooding mound by tongue, as the male malleefowl does. Or turning red in foot and beak as puffins do in mating time. Or living in symbiosis on a zebra's back like the African tickbird. Brenner introduces each of her two-page sketches with a question--which can be either lame and utilitarian (""Can a Bird Help Fishermen?"" Yes, Asian cormorants do), or narrowly focused (""Why Are Vultures Bald? . . . Because they spend a lot of time with their heads inside dead animals""), or vaguely intriguing (""Does the Bowerbird Know Beauty?""). One question, ""Can a Bird Use Tools,"" heads an entry that also takes up Darwin's concept of adaptation. (Both discussions center on the Galapagos finches.) Despite this brief foray into theory, Brenner doesn't really take her readers beyond the curiosity level. However, there's always a place for an easy, error-free book that makes animal habits interesting. For her part, Brady provides lifelike portraits which illustrate the featured eccentricity of each bird.