First find the new number of birds: 6 birds - 2 birds = <<6-2=4>>4 birds
Then find the new total number of animals: 6 monkeys + 4 birds = <<6+4=10>>10 animals
Then divide the number of monkeys by the number of animals and multiply by 100% to express the answer as a percentage: 6 monkeys / 10 animals * 100% = 60%
#### 60