Colour in a picture of a bird and maybe learn to recognise some.
In a six, let each cub pick a bird and colour it in- print enough that a couple can do the same bird if they want. Use the reference sheet so they can see what the birds should look like, and then at the end see if they can name the birds when the labels are taken away. If this is to meet the requirement of the naturalist badge then they need to go home, watch the garden regularly for a week and make a log of what birds they see.
This activity doesn't complete any badge requirements