How do you know if a duck is broody

[Southernchickens]

I have a nest full of pekin eggs in a dog house and for the past two days I have seen my mallard hen sitting on the nest like she was broody. Whenever I go out to the pen she jumps up and comes off the nest. But yesterday she was on the nest off and on and when I got home today she was sitting. Do yall think she is broody and what are the signs to look for? Will she quack more than usual or something?

 

[pekinduck<3er]

shell try to nip and bite and hiss at you to stay away from her nest if she is. when she gets up and comes back shes just leaving for a awhile. thats what wild mallards do. so try to get under her when shes on her nest see what she does and then tell

 

[One Acre Wonder Farm]

When my girls go broody they refuse to get off the nest and hiss if I come near. If they do get off (some are more shy than others), they'll stay near by and 'shout' at me until i move away from the nest.