Nice trellis system. The birds might be troubling you due to the size and shape of your vines. I'll take a pic of my vines and the trellis and post it here for you to see what I'm talking about. But in the mean time, I would recommend you prune your vines better next winter. Also, I see that your trying to propagate some new vines. Thats a pretty simple method your using! I use a misting box system. Which type of muscadines do you have?
I have about 80 vines now, both muscadine and scoppernong. I also have a few concords.
From the Getgo
in South Carolina