As in Emily Gravett's other picture books (Wolves; Little Mouse's Big Book of Fears etc.) there is much for adults to appreciate along with children. In The Odd Egg, Duck is the only bird without an egg, but he solves that problem by finding one. (I assumed that Duck is male because of his colouring; he's either a mallard or a khaki campbell. Duck's gender is confirmed in a reference to "his egg.") A single guy adopting is enough out-of-the-heteronormative-parenting-box for me to consider this a queer text. Plus, all of the other birds are shown as single parents and they seem to live in one big family group together.
I love Gravett's sense of humour. Duck holds one leg high while peering under his body, searching for an absent egg. Owl studies 'The Bright Baby Book' while sitting on her egg and the owlet hatches spouting mathematics. The young parrot's first words as he hatches are "I'm a pretty boy!" - as the parent parrot holds up a mirror. (This could also be construed as queer content, I suppose.) There is a playful surprise at the end, when Duck's giant egg hatches, and then the action continues across the end flaps and even onto the back cover, with one final "Quack!" Ages 3 - 6. (And definitely adults too.)