🧡

i think the robin is cold, that’s why it’s so round and fluffy

To be fluffy protects from cold

exactly, that's how it is
but it also enlarges the appearance, which is why some males do it to impress the girls 😀)

and for the budgies:
In budgerigars, fluffing up is thought to indicate different states of mind. However, even experts cannot interpret the bird's state of mind with certainty, as it varies from animal to animal. Budgerigars often fluff up when they are feeling well, and in this state the birds often sing.