Thanks. I ended up removing the fence. I was too concerned she wouldn't be able to flying in and out of the there very well (between the house and sidewalk so it's not a super huge area). We're just going to try keeping the cat out back under supervision when he does go out. He'll have to deal...
This is actually a wild mallard who laid eggs in the corner of our garden. We put up a small mesh “fence” (some metal stakes with deer netting, about 4 feet tall) to prevent our cat from going by the nest. However now I’m concerned that maybe I’m preventing mother duck from getting access to her...