Otto's blog

First guess:  they are all small.  
Second guess:  they were "give-aways"  
Third guess:  Owen chose them all
Fourth guess:  Miyo chose them  
Fifth guess:  Blogmaster Otto chose them to put in the bird box he made.

And Otto`s mum comes out swinging, with not one, but FIVE guesses! But are any of them correct...? 
Sorry mum, you`ll have to wait a few days to find out (and buttering me up by referring to me as Blogmaster Otto will get you no preferential treatment by the way).

Hello!  I write comment for the first time.
I guess all these are the same size.

Well, you`re 2/3rds correct - the dog & frog are a similar size, but the orange is normal size. 
Sorry, that`s not it!

My guess is that they are Owen's favorite objects at the moment.  :D

Mmmm. Interesting theory.
Interesting & WRONG!

They have a letter, 'g'.
They have a letter, 'o'.
Their shape are round or plump.
They have a white part.
They are from some shop.
Their last sound are G-sound.
Ah, I can't think any more!

There is one more my answer.
They are the color of Irish national flag that is green, white and orange. Green is the frog, white is the little ceramic dog and orange is the orange.
Is it no good?

They're Owen's like thing and they're give to Owen from shop.

That`s a good guess. Actually, the frog & dog were given to Owen by shop staff, but not the orange...