I know this is probably going to sound a bit crazy to you, but generally birds attack tomatoes because they are thirsty. You don't say where you live, but many parts of the US are having drought conditions.* I would suggest you put a birdbath nearby for them to drink from.* You can use a large plastic drainage saucer for pots as that will be shallow enough for them to drink or bathe.* Put a small rock in the center of it so it doesn't blow away if it empties.* You can put the saucer on just about anything from a tree stump to an overturned milk jug container.* Replinish the water every couple of days and wash out the saucer so it doesn't get lots of algae.* I did a google with the term :
birds + tomatoes
and found some great ideas.* You could repeat the search or even use the term:
birds + damage tomatoes
I'm including the cached version so you can easily find the info.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.