Personally I've always found Glimfeather's tu-whooing in the book amusing. I still get a chuckle out of it whenever I re-read the book.

But I think it's probably best that they leave it out of the film. even though I like it in the book, in the BBC adaptation I thought it was a little bit annoying, of course that doesn't mean it would automatically be a problem if it was left in the film. But I think it's the kind of thing that could annoy general audiences or make them laugh for the wrong reason.

That opening paragraph made me laugh.

I'd like a happy medium... if his lines are all lifted straight from the book, it could sound too repetitive, but I don't think he would feel like Glimfeather without at least a few tu-whoos. I'd keep a few rhyming sentences and then emphasize the unique, owl-ish way that Glimfeather pronounces "ooh" in the rest of his dialogue.

They would certainly have to do it right. I HATE to make yet another LotR comparison, but I think of Treebeard's "Hoo-ra-hoom" (or however it's spelled). In the book it's kind of weird, but in the movie it's barely noticeable. I think if they do it maybe like a bird/owl whistling sound effect, it would be perfectly fine.

I think they must have two or more in the movie, even if it's just when Glimfeather is excited or something. Or as fantasia_kitty put it, use a real animal sound, instead of some guy saying "tu-whoo."
They need to stay true to the books, and I didn't mind it in the BBC version. In fact, I thought it added something to him.

And I was disappointed that in the Prince Caspian movie Trumpkin only had one or two of his "horns and halibuts", "beards and bedsteads", "bilge and beanstalks", etc. In the book, he had many more.

But that's just me.

And I was disappointed that in the Prince Caspian movie Trumpkin only had one or two of his "horns and halibuts", "beards and bedsteads", "bilge and beanstalks", etc.

I agree, though I think that has more to do with the way they altered Trumpkin's character. The 2 times Peter Dinklage did give one of those exclamations ("beards and bedsteads" and "cakes and kettledrums"), it was really awkward because Movie-Trumpkin is so dour. It just didn't feel right.

I think they should cut all the "to-whoo"s and have the Talking Owls speak in normal-sounding English, to be consistent with what they've done before. They didn't have Mr. and Mrs. Beaver try to sound like real beavers, or Reepicheep all high-pitched and squeaky like a real mouse. It would get laughs for the wrong reasons and detract from the story.

I agree with you, King Erlian. The other movies didn't have especially animal sounding voices. They had animal appropriate voices. In the book or audiobook we have to be reminded that Glimfeather is an owl. In a movie it's right in front of you. When I think of an owl, I think of a wise old owl. Perhaps Glimfeather should sound rather old and eccentric combined with owl sounds when he is not actually saying words. He certainly should hoot, but not as a part of a word.

They didn't have Mr. and Mrs. Beaver try to sound like real beavers, or Reepicheep all high-pitched and squeaky like a real mouse.

The other movies didn't have especially animal sounding voices.

But they did have the wolves snarl and bark, and they did have the fox yipe when he was bitten. The cheetahs and leopards and Minotaurs were roaring in battle and Gryphons screeching as they flew in the sky.
I personally don't care one bit about consistency from the previous three movies as everything about TSC will be different. Different actors, different animation, different direction. But even if I did, the other movies did have the animals/creatures making noises in their "own languages".
Again, I don't want to hear Glimfeather actually say "tu-whoo" as he did in BBC. That'd be weird. But to do it as an owl whistle or something like that I think would be very appropriate and would work fine.

ETA: Oh yeah, if you're looking for animal noises while talking, Aslan does roar at the Witch while speaking to her.

I think the talking owls should talk with whatever accent the director wants, with CG owl hoots added. It could be laughable, but is accepted on stage, for a human in an animal costume to hoot in a human voice. But in a movie, there is so much more available - and surely sound techs can blend in voice and owl hoot?

I'd like a happy medium... if his lines are all lifted straight from the book, it could sound too repetitive, but I don't think he would feel like Glimfeather without at least a few tu-whoos.

I'm with the Dryad on this. A hoo or two, but don't overdo.

I wouldn't want the voice actor to actually pronounce "tu-whoo" and come to think of it I never imagined the "tu-whoo"s in the book coming from a human voice. If they include the "tu-whoo"s, I think it should be from an actual owl hooting. I'd rather the voice actor just speaks the lines (minus the "tu-whoo"s) and owl sounds are added in post-production. They could do it similar to how Aslan's line "Do not cite the Deep Magic to me, Witch!" blends Liam Neeson's voice with the growl of a lion.

As for the rhyming... if the actor can pull it off without it sounding silly, I wouldn't mind, but it's not too important to me. Actually, I generally prefer if the bulk of the dialogue is original and not lifted straight from the book - save for a few key lines. It's probably just because I dislike the mental effort of keeping myself from hearing movie dialogue in my head when I read a book.

Animal noises would be the best way to go here for me. After all, I do not want anyone to forget that these are owls. Owls should act like owls even if they talk. I think the real question for me is what kind of owls are they?

@eustace: Dialects of owlishness might be going a little too far, though.

I'd like a happy medium... if his lines are all lifted straight from the book, it could sound too repetitive, but I don't think he would feel like Glimfeather without at least a few tu-whoos.

I'm with the Dryad on this. A hoo or two, but don't overdo.

Dr Hoo, I presuume?

So, basically, I agree with the general consensus. fantasia_kitty said exactly what I was thinking about the animals from LWW blending voice actors words with animals sounds.