First, I'm so sorry for your loss...
Buy some screening from a hardware store (even Lowes, Home Depot, etc) that you use to repair window screens. Take scrap lumber (I used strips of OSB board cut into 2" strips) and fasten them together to make a "window frame" slightly bigger than your brooder. Staple the screening to the frame. I used this on top of my rubbermaid brooder. You can place a brick, wood, etc on top to weight it down. This will keep smaller animals out of your brooder, but not a determined predator....hope this helps.

Buy some screening from a hardware store (even Lowes, Home Depot, etc) that you use to repair window screens. Take scrap lumber (I used strips of OSB board cut into 2" strips) and fasten them together to make a "window frame" slightly bigger than your brooder. Staple the screening to the frame. I used this on top of my rubbermaid brooder. You can place a brick, wood, etc on top to weight it down. This will keep smaller animals out of your brooder, but not a determined predator....hope this helps.