Spring is in the air

My little house guest wants to get outside and I won't let her from fear that she'll run away. She goes home to her Mom in the weekends and gets to go outside there, in the environment she knows. But on sunny days like this one we need air in the kitchen/living room, so I keep a window open. And she knows what's on the other side! I try to block her way, but I'm afraid she'll manage to slip out sooner or later...