Shriveled leaves are often caused by herbicide contact.  This also could affect the grape development.  Is it possible that a herbicide was sprayed nearby?  Maybe on a windy day? The following website give other causes to consider.   It would be helpful to see one of the leaves to determine the type of damage.  It is unlikely that birds are the problem at this stage of grape development-they like ripe grapes.
1. https://apps.extension.umn.edu/garden/diagnose/plant/fruit/grape/
2. https://extension.umn.edu/fruit/growing-grapes-home-garden