What were some alternatives to slave labor?

Percentage of food eaten by the flock.

Explanation:

Since changes in bird numbers will be based on the beak phenotype for the second and third generation, you should use the table row that is most influenced by the differences between one beak phenotype and another. Birds use the beak to feed and transport materials, as the birds in your research will be stuck, the table line that will be most influenced by different beak types is feeding. For this reason, we can conclude that the "Percentage Of Food Eaten By The Flock" line will be the most appropriate for calculating new numbers.