a natural disaster has occurred on the island. the food source for the bird species above has drastically decreased. which beak depth would be most advantageous to survival if the only food source available was insects living deep within tree bark. a. G fortis beak depth of 13 mm because this is the longest break that will be able to reach further into the tree bark. b. G fortis beak depth 12 mm because these birds will be able to split the bark and get the food source. c. G fuliginosa beak depth 8 mm because there are more birds in this group than the others d. G fortis break depth 11 mm because there are so few members of this species.