Why does my duck only sit on her eggs at night?

[OutbackQuackers]

I have 2 call ducks one male and the other female (they are both 3 years old)
The two of them have just started to mate (it's the end of winter)
Daisy, the female duck has laid 5 eggs so far, and she won't sit on them during the day, only when I put her in the coop at night.

 

[Poultrybonkers]

She sits on the nest to lay another egg come morning mine does the same shes not broody is why

 

[Babe2]

I have 2 call ducks one male and the other female (they are both 3 years old)
The two of them have just started to mate (it's the end of winter)
Daisy, the female duck has laid 5 eggs so far, and she won't sit on them during the day, only when I put her in the coop at night.

We have some 'whistling' ducks that come into our back yard to eat some of the peanut* sunflowerseed bird food we put there in a "milkcan"!! Why would the duck lay and then leave it?