Question

Which type of birds were absent on Galapagos island when they were survived by Darwin?
A. Warblers and woodpeckers
B. Carnivores
C. Cactus feeding
D. Seed eating

Answer 1

During the migration process the birds migrate from island to island. So the birds which adapt with Darwin’s finches survive in the particular area during the drought or cold season. During drought years the birds with deeper beaks can only survive. Beak depth is the important feature in the birds for survival in any islands at any conditions. Maximum peak depth is about $9.6mm$ is the medium measurement in the Darwin selection process.

Complete answer:
Beak depth is the important one; it correlates with body size and the ability to crack the seeds. The dry seeds are produced during dry years and small seeds are produced during the wet season. So the difference in environmental patterns in Galapagos may vary by availability of the food sources like seeds, cactus, insects and fruits. Darwin noticed the fruit eating finches had parrot’s beak structure. They eat insects only. They have narrow beaks. Darwin’s finches area is a group of $18$ species which is classified by beak form and function. In drought season small seeds availability is less so the finch which eats small seeds may die because it has a small beak. During the Panama land bridge altered ocean circulation the finches came to the Galapagos Islands. In this island finches change their size of beak, claws. This change depends on the local food source. Finally Darwin concluded that during the migration it changes their body to survive on a new island.
Option (A) Warblers and Woodpeckers: Woodpeckers have pointed type’s beaks and warblers have acute beaks. Acute beaks are defined as the tapers to a fine point at an end. This is available in all insect eating birds. It has small beaks. During drought it does not survive.
Hence option (A) is correct.
Option (B) Carnivores: Carnivores' beak may vary based on what they eat and the way they hunt. It has a curved razor shaped tip to hunt prey's smaller parts. So, it can survive in any place.
Hence option (B) is incorrect.
Option (C) Cactus: Cactus is the stable one on this island. It gives the food for two species: finch, iguanas, doves, tortoise and mockingbirds.
Hence option (C) is incorrect.
Option (D) Seed eating finches: Seed eating finches also survive on this island because during fly time the population gradually helps for change in habitants.
Hence option (D) is incorrect.

Therefore, Option (A) warblers and woodpeckers is the correct answer.

Note:
Natural selection is important for finches living on the island. It is involved in which phenotypes that are favorable are more likely to survive and reproduce to produce the new one. Evolution is the change in genetic composition over successive generations. Large ground finch- Geospiza magnirostris, medium ground finch- G. fortis, small tree finches- Certhidea olivacea. Apart from the coco finch, other finches are found only at the Galapagos Islands. Darwin finally concludes that the phrase is called ‘survival of the fittest’.