Dear Hildegarde as in ""Dear Abby""--except that Hildegarde is an owl (motto on wall: ""Better to be wise than otherwise"") and her troubled correspondents are animals of various sorts. A dog objects to the name Bernard (""Why couldn't I have been given a decent dog name--something interesting like: Rover, Spot, Champ, or Prince?""). A giraffe's problem is, of course, ""I am extraordinarily tall."" A pig protests ""insulting remarks like. . . dirty pig""; a spider has trouble spinning a neat web; a female bird complains that her mate does nothing but whistle--and then calls it work. Some of these, like the giraffe's, are old plaints that elicit standard answers with a verbal twist (to the giraffe: ""Just continue being your own sweet uplifting self."") Some, most notably the bird's, reflect current, topical gripes--and get a properly up-to-date, also word-juggling reply (re mate Gus: ""Ask Gus if he ever heard of whistling while you work""). And there's an element of parody throughout. But that, together with the verbal hijinks and some of the plaints, seems altogether geared to an older child than the picture-book format suggests--however amusingly Waber's black-and-white sketches convey the animals' problems.