Birds

A bird's eye view
The bird has flown
A bird's passage
Free as a bird
A home bird
A little bird told me
A Rare bird
The birds and the bees
(strictly) for the birds
A lame duck
Sitting duck
Like a duck to the water

Dog
eat dog
dog somebody's footsteps
A dog in the manager
A dog's breakfast/dinner
Every dog has its day
Give a dog a bad name
fight like cat and dog
The hair of a dog
Not a dog chance
The tail is wagging the dog
Teach an old dog new tricks
Top dog
There's life in the old dog yet
In the dog house
Let sleeping dog lie
Go to the dog
Raining cats and dogs
Junkyard dog