These white breasted nuthatches are a couple. I have reason to believe that Poppa is helping Momma with some food here, as she is either filled with eggs ready to lay or is quickly leaving the nest for this rendezvous.
Nuthatches do not perch like most other birds you might normally see. Like Woodpeckers these guys are more likely to be seen clinging to the sides of trees than perched on a branch. This is springtime but this species stays all year round.