After seeing the size of an ostrich egg first-hand, I was amazed. How many of these eggs can an ostrich egg hen sit on, anyway? -- M.W.

She can "sit" gently, but effectively, on 20 eggs. Communal ostrich nests may contain 40 eggs, but the hen who's taken over the task of brooking them can handle only about twenty. DEAR DR. MILLER:

I paid plenty. Oh, I've got the bird all right, but he won't talk. He was guaranteed, and all he does is mutter something to himself that I can't understand. When I tried to get my money back, the guy I bought him from said that the bird IS talking, that it's my fault for not being able to understand his language. So where does this leave me?

With a scruffy little green parrot, bald-headed to boot, I have named Mumbles. Me, my friends have renamed Grumbles because the guy that sold me that bird has flown the coop. Having had Mumbles a year now, I've been told it's too late to expect him to improve? -- K.L.

Mumbles' mutterings may be more interesting than you think if you could only turn up the volume. Try an inconspicious tape recording, and turn that up just to see what he's been talking about for the past year. The chances of him acquiring a whole new language (yours) are, unfortunately, slight at this late.

Improvement should be possible, if not linguistically, at least as far as Mumbles' looks are concerned. A local bird-oriented veterinarian may be able to come up with keys to improving his habitat and health to the point that his plumage may be restored. DEAR DR. MILLER:

Can a dog still go through heat even if she has been spayed? If not, can you tell me why at the same time every year she starts breathing hard and chews our gate and does other bad things? -- S.B.

No, a spayed dog should not go into heat. The next time yours starts breathing hard (or whatever), her own veterinarian (after a check-up) could probably tell you just what is, or isn't going on.